Sex Hormone-binding Globulin Research Articles

Use of calculated free testosterone in men: advantages and limitations.

Due to technical requirements and high cost, equilibrium dialysis-free testosterone (T) measurements are not commonly available in clinical practice. Clinicians rely on calculated free T (cFT) as a proxy. This review discusses using free T as a second-line assessment, highlighting its relevance in preventing misdiagnosis and overtreatment of male hypogonadism. While there is consensus on measuring total T - comprising sex hormone-binding globulin (SHBG)-bound, albumin-bound, and free T - as a first step in diagnosing male hypogonadism, evidence confirms that aging and conditions like obesity influence both total T and SHBG levels. Furthermore, low free T has been associated with symptoms of androgen deficiency, even in men with normal total T. Clinicians should, however, be aware of limitations of free T calculations, particularly the lack of standardization. Recent developments include establishing age-stratified free T reference ranges measured by equilibrium dialysis. Free T remains a subject of longstanding controversy. Factors such as age and obesity can alter total T and SHBG levels. Free T serves as a second-line indicator of androgen exposure, taking SHBG fluctuations into account. Given that commonly used free T calculators only provide approximations of free T, there is a need to further standardize free T calculators.

Prenatal phthalate exposure and pubertal development in 16-year-old daughters: reproductive hormones and number of ovarian follicles.

Is there a possible association between prenatal phthalate exposure and late effects in teenage daughters with respect to reproductive hormone levels, uterine volume, and number of ovarian follicles? Our study showed subtle associations between phthalate metabolite concentrations in maternal serum from pregnancy or cord blood and LH and insulin-like growth factor 1 (IGF-1) levels as well as uterine volume in their daughters 16 years later. Endocrine-disrupting environmental chemicals may adversely affect human reproductive health, and many societies have experienced a trend toward earlier puberty and an increasing prevalence of infertility in young couples. The scientific evidence of adverse effects of foetal exposure to a large range of chemicals, including phthalates, on male reproductive health is growing, but very few studies have explored effects on female reproduction. This follow-up study included 317 teenage daughters who were part of the Copenhagen Mother-Child Cohort, a population-based longitudinal birth cohort of 1210 females born between 1997 and 2002. A total of 317 female participants (median age 16 years) were examined for weight, height, and menstrual pattern. A serum sample was analysed for concentrations of reproductive hormones, and trans-abdominal 3D ultrasonography was performed to obtain the number of ovarian follicles, ovarian and uterine size. Prenatal maternal serum samples were available for 115 females, and cord blood samples were available for 118 females. These were analysed for concentrations of 32 phthalate metabolites. Weighted quantile sum regression was used for modelling associations of combined prenatal phthalate exposure with the reproductive outcomes in post-menarcheal females. In bivariate correlation analyses, negative significant associations were found between several prenatal phthalate metabolite concentrations and serum hormone concentrations (testosterone, 17-OH-progesterone, and IGF-1) as well as number of ovarian follicles in puberty. Positive significant correlations were found between prenatal phthalate exposure and FSH and sex hormone-binding globulin concentrations. Combined analyses of phthalate exposure (weighted quantile sums) showed significant negative associations with IGF-1 concentration and uterine volume as well as a significant positive association with LH concentration. Phthalate metabolites were measured in serum from single prenatal maternal blood samples and cord blood samples. Potential concomitant exposure to other endocrine-disrupting environmental chemicals before or after birth was not controlled for. The study population size was limited. Our results support the need for further research into possible adverse effects of environmental chemicals during foetal development of the female reproductive system. The work was supported by The Center on Endocrine Disruptors (CeHoS) under The Danish Environmental Protection Agency and The Ministry of Environment and Food (grant number: MST-621-00 065). No conflicts of interest are declared. N/A.

Functional hypothalamic amenorrhoea and polycystic ovarian morphology: a narrative review about an intriguing association.

Functional hypothalamic amenorrhoea (FHA) is responsible for 20-35% of all cases of secondary amenorrhoea and, thus, is the second most common cause of secondary amenorrhoea after polycystic ovary syndrome (PCOS). A high number of patients with FHA reveal polycystic ovarian morphology (PCOM) on ultrasound. The combination of amenorrhoea and PCOM can lead to confusion. First, amenorrhoeic women with PCOM fulfil the revised Rotterdam criteria and, thus, can easily be misdiagnosed with PCOS. Moreover, it has been claimed that some women with FHA and concomitant PCOM differ from those without PCOM in terms of endocrine regulation and metabolic traits. The main focus of this article was on studies about FHA, which differentiated between patients with or without PCOM. The aim was to estimate the prevalence of PCOM and to look if it has an impact on pathophysiologic, diagnostic and therapeutic issues as well as on long-term consequences. Peer review original and review articles were selected from PubMed searches for this review. Searches were performed using the search terms 'polycystic AND functional hypothalamic amenorrhoea'. The reference lists of publications found were searched for relevant additional studies. The inclusion criteria for publications were: English language, patients' age ≥ 18 years, year of publication >1980, original studies, validated diagnosis of FHA, and validated diagnosis of PCOM using transvaginal ultrasound. The prevalence of PCOM in women with FHA varied from 41.9% to 46.7%, which is higher than in healthy non-PCOS controls. Hypothetically, the high prevalence might be due to a mixture of silent PCOM, as in the general population, and pre-existing PCOS. Several differences in metabolic and hormonal parameters were found between FHA-PCOM and FHA-non-PCOM patients. While oestrogen deficiency is common to both groups of patients, FHA-PCOM patients have a higher BMI, higher levels of anti-Müllerian hormone (AMH) and testosterone, a higher increase in LH in the course of a GnRH test, and lower sex hormone binding globulin (SHBG) levels than FHA-non-PCOM patients. The differential diagnosis between FHA-PCOM and PCOS, especially PCOS phenotype D (PCOM and oligo-/anovulation without hyperandrogenism), can be challenging. Several parameters have been suggested, which are helpful though not absolutely reliable. They include the typical causes for FHA (excessive exercise, energy deficit, and/or psychological stress), the serum levels of LH, testosterone, and SHBG, as well as the progestin challenge test. Whether FHA-PCOM has a different risk profile for long-term consequences concerning patients' metabolic and cardiovascular situation as well as their bone mass, is unclear. Concerning therapeutic aspects, there are only few data about FHA-PCOM compared to FHA-non-PCOM. To treat anovulation, the use of pulsatile GnRH treatment seems to be equally effective in both groups. Similar to FHA-non-PCOM patients, pulsatile GnRH therapy would be more efficient than exogenous gonadotropins in FHA-PCOM patients. Women with FHA-PCOM present a special sub-population of FHA patients. The diagnostic pitfall of FHA-PCOM should be emphasized in clinical guidelines about FHA and PCOS. The fact that almost half of the women with FHA have an ovarian follicle excess (i.e. PCOM) in face of low gonadotropin serum levels suggests that the intra-ovarian regulation of folliculogenesis is subject to individual variations, for unknown reasons, either genetic or epigenetic. Further studies are needed to investigate this hypothesis. Not applicable.

Pre-Conception Androgen Levels and Obstetric Outcomes in Polycystic Ovary Syndrome: A Single-Center Retrospective Study

Hyperandrogenism is a determining diagnostic factor for PCOS. If pregnancy is conceived, it is considered high-risk due to several potential complications, but the correlation between pre-pregnancy androgen levels and obstetric outcomes is poorly characterized. Objective: To determine if pre-pregnancy serum androgen concentrations and androgen indexes differed when certain obstetric and neonatal outcomes appeared in PCOS. Methods: A single-center, retrospective study was carried out. All patients were treated between 2012 and 2019. A total of 73 patients had all the endocrine and obstetric data available. Pre-pregnancy hormone levels (total testosterone-T, androstenedione-AD, DHEAS (dehydroepiandrosterone sulfate), SHBG (sex-hormone-binding globulin), and TSH (thyroid-stimulating hormone) were collected, and T/SHBG, AD/SHBG, DHEAS/SHBG, T/AD indexes were calculated and compared. Results: When miscarriage was present in the history, significantly elevated pre-pregnancy AD levels were observed. Higher pre-pregnancy AD level was noted in PCOS patients delivering female newborns as compared to males. Additionally, a higher T/AD ratio was associated with subsequent preterm delivery, but significance was lost after age adjustment. Maternal age at delivery had a significant negative correlation with pre-pregnancy DHEAS levels and DHEAS/SHBG ratio. Pre-pregnancy SHBG displayed a significant negative correlation, while pre-pregnancy androgen/SHBG ratios exhibited positive correlations with both birth weight and birth weight percentile. Conclusions: Based on our data, AD and the T/AD ratio emerge as distinctive factors in certain outcomes, implying a potential specific role of altered 17-β-HSD (17β-hydroxysteroid dehydrogenase) enzyme activity, possibly influencing offspring outcomes. The pre-pregnancy T/SHBG ratio exhibits a potentially stronger correlation with fetal growth potential compared to SHBG alone. DHEAS and maternal age at delivery are strongly correlated in PCOS patients.

Type 1 diabetes mellitus; ovarian reserve; anti-Müllerian hormone; ovarian function

BACKGROUND: Prolonged course of diabetes mellitus often leads to the development of vascular complications, insufficiency of ovarian function. The occurrence of diabetes mellitus in women before pregnancy (pregestational diabetes mellitus) it can have various adverse consequences for the mother, fetus, child and the course of pregnancy. Pregnancy planning in women with pregestational diabetes significantly improves the outcomes of pregnancy and childbirth. AIM: The aim of this study was to analyze gonadotropic and ovarian function parameters in patients with type 1 diabetes mellitus depending on the age of onset, duration and compensation level of the disease. MATERIALS AND METHODS: The patients included into this clinical prospective study were divided into two groups. The main group consisted of 216 patients with type 1 diabetes mellitus aged 18 to 39 years (mean age: 27.1 ± 3.1 years). The control group consisted of 30 healthy women of reproductive age. Chemiluminescent immunoassay was used to determine blood serum levels of anti-Müllerian hormone, follicle-stimulating hormone, luteinizing hormone, prolactin, estradiol, testosterone, free testosterone, and sex hormone-binding globulin from day 2 to day 5 of the menstrual cycle. Serum progesterone levels were measured on days 20–23 of the menstrual cycle for three consecutive cycles. Glycated hemoglobin levels were also studied in the blood serum of patients with type 1 diabetes mellitus. All the patients underwent pelvic ultrasound examination to assess the cohort of antral follicles and ovarian volume. RESULTS: The average age of menarche in patients with type 1 diabetes mellitus who developed the disease at the age of under 10 years was 14.2 ± 1.2 years. This was higher than in the group of girls with the onset of the disease over the age of 10 years (13.5 ± 1.2 years) and in women of the control group (11.9 ± 1.1 years). When assessing the ovarian reserve in patients with type 1 diabetes mellitus, we found a decrease in anti-Müllerian hormone level and antral follicle count in the group of women with disease onset at the age of under 10 years. We did not find differences in the ovarian reserve parameters in patients depending on disease duration. Normogonadotropic normoprolactinemic ovarian insufficiency was detected in 154 (71.3%) of 216 patients, while the rest 62 (28.7%) women had an ovulatory menstrual cycle. In patients with anovulation, luteal phase deficiency and ovulatory menstrual cycle, we found no differences between the age of development of type 1 diabetes mellitus, its duration, glycated hemoglobin levels, total daily insulin dose and insulin dose per kilogram of body mass. In patients receiving intensive insulin therapy with continuous subcutaneous insulin infusion, glycated hemoglobin level was lower than in those receiving multiple dose insulin injection therapy. CONCLUSIONS: The average age of menarche in patients with type 1 diabetes mellitus is higher than in healthy women. The ovarian reserve parameters in patients with early onset of the disease, before 10 years of age, are lower than in patients who developed type 1 diabetes mellitus after 10 years of age. Duration of pregnancy planning period depends on compensation level of the disease and lasts from six to 12 months. This requires the doctor and patient to prepare for the implementation of reproductive tasks as early as possible, especially in patients whose disease onset occurred in pre-pubertal period.

Nonlinear association of sex hormone-binding globulin levels and chronic kidney disease, an analysis based on the National Health and Nutrition Examination Survey (NHANES) 2013–2016

Studies on the relationship between serum sex hormone-binding globulin (SHBG) levels and chronic kidney disease (CKD) remain limited and inconclusive. Therefore, this study aims to evaluate the effects of SHBG on CKD in a nationally representative population. We included a total of 7713 adults from the National Health and Nutrition Examination Survey (NHANES) conducted between 2013 and 2016. Multivariate logistic regression models were utilized to evaluate the association between SHBG levels and CKD, and odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Additionally, we employed a restricted cubic-spline regression model to explore potential dose-response associations. Among the participants, 4030 (52.2%) were women, and CKD was observed in 13.50% (1043/7713). After adjusting for various variables, SHBG levels were found to be associated with the risk of CKD (OR: 1.24; 95% CI: 1.11–1.38), indicating a 24% higher risk of CKD for SHBG levels (log2-transformed). A comparison between the highest quartile (Q4) and the lowest quartile (Q1) of SHBG levels revealed an OR of 1.51 (95% CI: 1.17–1.95) for CKD prevalence. Notably, while the association between SHBG and the risk of CKD disappeared when SHBG levels were <46.1 nmol/l, it existed when SHBG levels exceeded 46.1 nmol/l. Taken together, these findings indicate nonlinear correlations between serum SHBG levels and CKD, with the inflection point occurring at approximately 46.1 nmol/l, which suggest that SHBG levels could serve as a useful marker for assessing CKD risk, with potential applications in early detection and management strategies.

Associations of Serum Testosterone and Sex Hormone-Binding Globulin with Incident Fractures in Middle-Aged to Older Men.

As men age, circulating testosterone (T) decreases, circulating sex-hormone binding globulin (SHBG) increases, and risk of fracture increases. It is unclear if circulating T, independently of comorbidities, is associated with fracture risk in men. To determine associations for T and SHBG with incident fractures in men. We utilized the large (n=205,973 participants, 11,088 any fracture cases, 1,680 hip fracture cases, 1,366 forearm fracture cases) and well-characterized UK Biobank cohort. Associations were modelled using Cox regressions, adjusting for multiple comorbidities/covariates, imputing for missing information, and assessing non-linearity using cubic splines. For T, not considering SHBG, there was a non-linear association with hip but not forearm fractures, with the lowest risk in the second quintile. However, in models adjusted for SHBG or using calculated free T, lower T was associated with higher risk for fractures at all evaluated bone sites. Lower SHBG was strongly associated with lower risk of hip and forearm fractures (Q1 vs Q5, hip 0.55, 0.47-0.65; forearm 0.62, 0.52-0.74). Low circulating SHBG is strongly associated with low risk of fracture at all evaluated bone sites, while the associations of circulating T with fracture risk are of lesser magnitude, non-linear, inconsistent among fracture site, and affected by adjustment for SHBG. These findings demonstrate that circulating SHBG, rather than T, is a major independent biomarker of fracture risk in men. Consequently, both total T and SHBG should be assessed when examining the relationship of endogenous T concentrations with fractures in middle-aged to older men.

Androgen Deficiency, Associations and Survival of Men With Stage 4 and 5 Chronic Kidney Disease: A Cohort Study.

Anaemia is a key cause of morbidity in chronic kidney disease (CKD). Androgen deficiency (AD) in males can contribute to anaemia of all causes, including in CKD. We sought to examine the prevalence of AD in men with CKD, the extent to which it contributed to anaemia and whether it was independently associated with long-term survival. This cross-sectional observational study was conducted among males aged 18 years and over with CKD stages 4 and 5. The study analysed morning blood samples with regard to their full blood count, urea and electrolytes, albumin, lipids, testosterone (T) and sex hormone binding globulin, with calculation of free testosterone by mass action equation. Mortality data were obtained 15 years later for survival analysis. Among 322 patients with a mean age of 63 years, the overall prevalence of AD was 68.9%. There was a statistically significant negative correlation between erythropoiesis stimulating agent (ESA) dose and testosterone concentrations (Pearson correlation -0.193, p = 0.05). There was a positive correlation between haemoglobin (Hb) and free testosterone level among patients not on ESA therapy (Pearson correlation 0.331, p < 0.001). Kaplan-Meier plots showed p < 0.001 on log-rank analysis, indicating that AD was significantly associated with worse survival. However, in Cox regression analysis, free testosterone was not associated with survival (95% CI for free testosterone 0.997-1.000). AD is highly prevalent among this population, and increases further with older age and more severe CKD warranting haemodialysis. Association of lower Hb and higher ESA dose with lower T concentration might be causative, which has important pharmaco-economic as well as clinical implications. Lower survival in men with low T, more likely reflects overall poor health rather than causation. A properly constituted randomised controlled study evaluating the effect of native T replacement is warranted in men with CKD and AD.

8377 Associations of Serum Testosterone and Sex Hormone-Binding Globulin with Incident Fractures in Middle-Aged to Older Men

Abstract Disclosure: L. Grahnemo: None. R.J. Marriott: None. K. Murray: None. L. Tyack: None. M. Nethander: None. A.M. Matsumoto: None. E.S. Orwoll: None. D. Vanderschueren: None. B.B. Yeap: None. C. Ohlsson: None. As men age, their circulating testosterone (T) decreases, circulating sex-hormone binding globulin (SHBG) increases, and risk of bone fracture increases. Unexpectedly, a recent large clinical trial reported that T treatment increased fracture risk in men. It is unclear if circulating T, independently of comorbidities, is associated with male fracture risk. We tested the hypothesis that serum T concentration is an independent risk predictor for incident bone fractures in men. We analyzed associations for T and SHBG with incident fractures in the large and well-characterized UK Biobank cohort (205,973 male participants median age 58 years, excluding men on androgen-related therapies). Baseline serum total T and SHBG were measured by immunoassay, and incident fractures documented over a median follow-up of 13.6 years (11,088 any fracture cases; 1,680 hip fracture cases; 1,366 forearm fracture cases). Associations of hormonal variables with fracture outcomes were modelled using Cox regression, adjusted for multiple comorbidities/covariates, with imputation for missing data, and non-linearity assessed using cubic splines. For total T, in multivariable models not including SHBG, there was a non-linear association with any fracture and hip fractures but not forearm fractures, with the lowest risk in the second quintile (Q2; hazard ratio (HR), 95% confidence intervals (CIs) Q2 vs Q5 any fracture 0.89, 0.84-0.94; hip fracture 0.76, 0.66-0.87; forearm fracture 0.97, 0.83-1.13). However, in multivariable models analyzing total T which were adjusted for SHBG, lower total T was associated with higher risk for fractures at all evaluated bone sites (HR, 95% CIs Q1 vs Q5 any fracture 1.24, 1.16-1.33; hip fracture 1.28, 1.08-1.51; forearm fracture 1.51, 1.25-1.82). Similar results were seen in multivariable models using calculated free T values. Lower SHBG concentration was associated with lower risk of any fracture, hip fractures, and forearm fractures, in multivariable models not including total T (HR, 95% CIs Q1 vs Q5, any fracture 0.71, 0.67-0.75; hip fracture 0.55, 0.47-0.65; forearm fracture 0.62, 0.52-0.74), with similar results following additional adjustment for total T. In conclusion, associations of total T concentrations with fracture risk without adjustment for SHBG are non-linear and inconsistent, whereas lower total T concentration, adjusted for SHBG, was independently associated with higher risks of any fracture, hip fractures, and forearm fractures. Lower circulating SHBG, without or with adjustment for total T, was strongly associated with lower risk of fractures at all three sites, consistent with SHBG being a major independent biomarker of fracture risk in men. When examining the relationship of endogenous T concentrations with health outcomes influenced by androgen-sensitive tissues in middle-aged to older men, both total T and SHBG concentrations should be assessed. Presentation: 6/2/2024

9208 Sex Hormones and Abdominal Muscle Area and Radiodensity in Men: A Multi-Ethnic Study of Atherosclerosis

Abstract Disclosure: A. Osmancevic: None. M. Allison: None. I. Miljkovic: None. C. Vella: None. P. Ouyang: None. P. Trimpou: None. B. Daka: None. Context: Information on the associations of testosterone, estradiol and sex hormone binding globulin (SHBG) levels with abdominal muscle volume and quality in men are unclear. Objective: To investigate the association between fasting serum sex hormones and CT-derived abdominal muscle area and radiodensity in adult men. Design: Cross sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis. Participants: A community-based sample of 907 men aged 45-84 years; 878 men with complete data were included in the analysis. Main Outcome Measure(s): CT scans of the abdomen were interrogated for muscle characteristics. Multivariable linear regressions were used to test the associations. Results: After adjustment for age, race/ethnicity, visceral fat, CRP, lifestyle factors, comorbidities and medicine use, higher levels of both total testosterone and estradiol, but not SHBG, were associated with higher abdominal muscle area (B= 1.79, 95% CI 0.1 to 3.4, &amp; B=1.79, 95% CI 0.4 to 3.2, respectively). After the same adjustment, levels of total testosterone showed a significant positive association (B= 0.3, 95% CI 0.0 to 0.6), while a significant inverse relationship was observed for SHBG with abdominal muscle radiodensity (B=-0.34, 95% CI -0.6 to -0.1). Conclusion: Our results indicate significant associations between sex hormones and abdominal muscle characteristics in men from several different race/ethnic groups. These findings reveal novel insights into the previously unrecognized role that SHBG may play in skeletal muscle adipose tissue distribution. Presentation: 6/2/2024

7896 Sex Hormones and Abdominal Muscle Area and Radiodensity in Men: A Multi-Ethnic Study of Atherosclerosis

Abstract Disclosure: A. Osmancevic: None. M. Allison: None. I. Miljkovic: None. C. Vella: None. P. Ouyang: None. P. Trimpou: None. B. Daka: None. Context: Information on the associations of testosterone, estradiol and sex hormone binding globulin (SHBG) levels with abdominal muscle volume and quality in men are unclear. Objective: To investigate the association between fasting serum sex hormones and CT-derived abdominal muscle area and radiodensity in adult men. Design: Cross sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis. Participants: A community-based sample of 907 men aged 45-84 years; 878 men with complete data were included in the analysis. Main Outcome Measure(s): CT scans of the abdomen were interrogated for muscle characteristics. Multivariable linear regressions were used to test the associations. Results: After adjustment for age, race/ethnicity, visceral fat, CRP, lifestyle factors, comorbidities and medicine use, higher levels of both total testosterone and estradiol, but not SHBG, were associated with higher abdominal muscle area (B= 1.79, 95% CI 0.1 to 3.4, &amp; B=1.79, 95% CI 0.4 to 3.2, respectively). After the same adjustment, levels of total testosterone showed a significant positive association (B= 0.3, 95% CI 0.0 to 0.6), while a significant inverse relationship was observed for SHBG with abdominal muscle radiodensity (B=-0.34, 95% CI -0.6 to -0.1). Conclusion: Our results indicate significant associations between sex hormones and abdominal muscle characteristics in men from several different race/ethnic groups. These findings reveal novel insights into the previously unrecognized role that SHBG may play in skeletal muscle adipose tissue distribution. Presentation: 6/2/2024

9208 Sex Hormones and Abdominal Muscle Area and Radiodensity in Men: A Multi-Ethnic Study of Atherosclerosis

Abstract Disclosure: A. Osmancevic: None. M. Allison: None. I. Miljkovic: None. C. Vella: None. P. Ouyang: None. P. Trimpou: None. B. Daka: None. Context: Information on the associations of testosterone, estradiol and sex hormone binding globulin (SHBG) levels with abdominal muscle volume and quality in men are unclear. Objective: To investigate the association between fasting serum sex hormones and CT-derived abdominal muscle area and radiodensity in adult men. Design: Cross sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis. Participants: A community-based sample of 907 men aged 45-84 years; 878 men with complete data were included in the analysis. Main Outcome Measure(s): CT scans of the abdomen were interrogated for muscle characteristics. Multivariable linear regressions were used to test the associations. Results: After adjustment for age, race/ethnicity, visceral fat, CRP, lifestyle factors, comorbidities and medicine use, higher levels of both total testosterone and estradiol, but not SHBG, were associated with higher abdominal muscle area (B= 1.79, 95% CI 0.1 to 3.4, &amp; B=1.79, 95% CI 0.4 to 3.2, respectively). After the same adjustment, levels of total testosterone showed a significant positive association (B= 0.3, 95% CI 0.0 to 0.6), while a significant inverse relationship was observed for SHBG with abdominal muscle radiodensity (B=-0.34, 95% CI -0.6 to -0.1). Conclusion: Our results indicate significant associations between sex hormones and abdominal muscle characteristics in men from several different race/ethnic groups. These findings reveal novel insights into the previously unrecognized role that SHBG may play in skeletal muscle adipose tissue distribution. Presentation: 6/2/2024

9240 Role Of Genetics In The Age-Related Testosterone Decline In Men: A UK Biobank Study

Abstract Disclosure: L. Ogoniak: None. S. Sandmann: None. J. Varghese: None. A.S. Busch: None. Background: Age-related decline in circulating serum testosterone concentrations is a well-established phenomenon in men. While the decline is partially linked to comorbidities such as obesity, type 2 diabetes (T2D), and cardiovascular disease (CVD), healthy ageing men present with rather stable levels. Recent genetic mapping studies demonstrated a large influence of common genetic variation on testosterone levels in men. However, increasing incidence rates of comorbidities in the ageing population are posing a challenge for the disentanglement of effects. Objective: Our study aims to investigate the genetic component of age-dependent testosterone decline in men. We hypothesize that the decline in testosterone levels in ageing men is primarily influenced by comorbidities, without significant alterations in the genetic architecture of testosterone levels. Material and Methods: We included 6,406 men with baseline and follow-up measurements of circulating serum concentrations of total testosterone (T), bioavailable testosterone (BAT) and sex hormone-binding globulin (SHBG) representing an independent sub-cohort of the UK Biobank study. We 1) assessed the association of baseline levels with the decline in sex steroids and 2) developed and verified polygenic risk score (PRS) models for T, BAT and SHBG based on 183,909 men from the UK Biobank (sub cohorts: 70% base, 15% target and 15% validation, follow-up cohort excluded for PRS development). Results: In the follow-up sub cohort, mean age (SD) at baseline was 58.2 yrs ( 7.5) and mean (SD) follow-up period was 4.3 (1.0) yrs. Mean (SD) BAT at baseline were 5.2 (1.32) nmol/L with a mean (SD) decline of 1.6 (24.4) % at follow-up. Baseline BAT, T and SHBG levels were significantly associated with the relative change of the respective biomarker at follow-up (-7.8, -2.9 and -0.4% per nmol/L, respectively, all p &amp;lt;0.001). After correcting for age at baseline, follow-up period and principal components 1-10, PGSTestosterone and PGSBAT were not associated with relative decline of the respective biomarker (both p = n.s.). Conclusion: Our study did not find evidence supporting a genetic component in the age-related decline of circulating serum T or BAT concentrations. Instead, in accordance to previous observational studies, our results suggest that rather non-genetic factors, e.g. increasing incidence rates of comorbidities, drive the age-related decline in sex steroid levels in men. Our study contributes to understanding the intricate relationship between genetic and non-genetic factors with age-related testosterone decline in men and offers valuable insights for potential interventions targeting age-related hormonal changes and associated health outcomes. Presentation: 6/2/2024

7078 Diagnostic Obstacles in Thyroid-Stimulating Hormone-Secreting Pituitary Adenoma (TSH-oma): A Case Report

Abstract Disclosure: V.A. Mendpara: None. P.P. Rao: None. M.D. Lundholm: None. Background: Thyroid-stimulating hormone-secreting pituitary adenoma (TSH-oma) is a rare cause of hyperthyroidism, forming 0.5-3% of all functioning pituitary tumors and &amp;lt;1% of hyperthyroid cases. Here, TSH secretion is autonomous and unresponsive to the normal negative feedback of thyroid hormones, leading to inappropriate TSH, T4 and T3 elevation. In the absence of clinical symptoms it can be difficult to distinguish between thyroid hormone resistance (THR) and lab errors. Clinical Case: A 44-year-old Swahili-speaking female with a history of type 2 diabetes was admitted for hypoglycemia requiring insulin adjustment. In her workup, thyroid function tests were obtained, revealing normal or low TSH (0.28 mIU/L) and high free T4 levels (2.7 ng/dL). At outpatient follow-up, repeat labs showed elevated TSH, T3 and FT4 (5.22 mIU/L, 377 ng/dL and 4.7 ng/dL, respectively). She reported weight loss, occasional palpitations, and chronic insomnia but denied other symptoms. Graves' antibodies (TSI, TSHR Ab) were negative. On exam, she had a 30-40 gm, smooth, non-tender thyroid without adenopathy, and a BMI of 23 kg/m2. The initial differential diagnosis included TFT lab error, THR or TSH-oma. A FT4 by equilibrium dialysis was high at 7.8 ng/dL (1.1-2.4 ng/dL). N-telopeptide (NTX) and sex hormone-binding globulin (SHBG) were elevated, consistent with a true hyperthyroid state. Genetic testing for THR posed time and cost barriers. Elevated alpha-subunit levels (87 ng/mL, normal ≤1.8 ng/mL) with normal levels of other pituitary hormones prompted a pituitary MRI, unveiling a 4.7 cm suprasellar bilobed pituitary mass abutting the optic chiasm and invading the cavernous and sphenoidal sinuses. She denied peripheral vision loss or headaches. Hyperthyroidism was managed with methimazole until surgical intervention for the TSH-oma. A transsphenoidal resection was performed with histopathological confirmation of a TSH-staining pituitary adenoma. She was started on levothyroxine for central hypothyroidism thereafter. Discussion: It is challenging to find the cause of abnormal TFTs when patients are asymptomatic and the differential includes THR, lab errors or TSH-oma. Inaccurate diagnosis can lead to delays in care or unnecessary thyroid ablation or pituitary surgery. Conversely, early identification and appropriate treatment of TSH-omas can prevent neurological and endocrinological complications, such as optic chiasm compression, visual disturbances, headache and hypopituitarism. Despite a lack of convincing symptoms of hyperthyroidism, we used confirmatory labs (NTX, SHBG) to rule in biochemical hyperthyroidism along with alpha-subunit testing and pituitary MRI to solidify the TSH-oma diagnosis, leading to surgical intervention. This case highlights the vital steps in the diagnosis of a TSH-oma, emphasizing the need for logical evaluation and differentiation of this rare condition. Presentation: 6/1/2024

8039 Role Of Genetics In The Age-Related Testosterone Decline In Men: A UK Biobank Study

Abstract Disclosure: L. Ogoniak: None. S. Sandmann: None. J. Varghese: None. A.S. Busch: None. Background: Age-related decline in circulating serum testosterone concentrations is a well-established phenomenon in men. While the decline is partially linked to comorbidities such as obesity, type 2 diabetes (T2D), and cardiovascular disease (CVD), healthy ageing men present with rather stable levels. Recent genetic mapping studies demonstrated a large influence of common genetic variation on testosterone levels in men. However, increasing incidence rates of comorbidities in the ageing population are posing a challenge for the disentanglement of effects. Objective: Our study aims to investigate the genetic component of age-dependent testosterone decline in men. We hypothesize that the decline in testosterone levels in ageing men is primarily influenced by comorbidities, without significant alterations in the genetic architecture of testosterone levels. Material and Methods: We included 6,406 men with baseline and follow-up measurements of circulating serum concentrations of total testosterone (T), bioavailable testosterone (BAT) and sex hormone-binding globulin (SHBG) representing an independent sub-cohort of the UK Biobank study. We 1) assessed the association of baseline levels with the decline in sex steroids and 2) developed and verified polygenic risk score (PRS) models for T, BAT and SHBG based on 183,909 men from the UK Biobank (sub cohorts: 70% base, 15% target and 15% validation, follow-up cohort excluded for PRS development). Results: In the follow-up sub cohort, mean age (SD) at baseline was 58.2 yrs ( 7.5) and mean (SD) follow-up period was 4.3 (1.0) yrs. Mean (SD) BAT at baseline were 5.2 (1.32) nmol/L with a mean (SD) decline of 1.6 (24.4) % at follow-up. Baseline BAT, T and SHBG levels were significantly associated with the relative change of the respective biomarker at follow-up (-7.8, -2.9 and -0.4% per nmol/L, respectively, all p &amp;lt;0.001). After correcting for age at baseline, follow-up period and principal components 1-10, PGSTestosterone and PGSBAT were not associated with relative decline of the respective biomarker (both p = n.s.). Conclusion: Our study did not find evidence supporting a genetic component in the age-related decline of circulating serum T or BAT concentrations. Instead, in accordance to previous observational studies, our results suggest that rather non-genetic factors, e.g. increasing incidence rates of comorbidities, drive the age-related decline in sex steroid levels in men. Our study contributes to understanding the intricate relationship between genetic and non-genetic factors with age-related testosterone decline in men and offers valuable insights for potential interventions targeting age-related hormonal changes and associated health outcomes. Presentation: 6/2/2024

9240 Role Of Genetics In The Age-Related Testosterone Decline In Men: A UK Biobank Study

Abstract Disclosure: L. Ogoniak: None. S. Sandmann: None. J. Varghese: None. A.S. Busch: None. Background: Age-related decline in circulating serum testosterone concentrations is a well-established phenomenon in men. While the decline is partially linked to comorbidities such as obesity, type 2 diabetes (T2D), and cardiovascular disease (CVD), healthy ageing men present with rather stable levels. Recent genetic mapping studies demonstrated a large influence of common genetic variation on testosterone levels in men. However, increasing incidence rates of comorbidities in the ageing population are posing a challenge for the disentanglement of effects. Objective: Our study aims to investigate the genetic component of age-dependent testosterone decline in men. We hypothesize that the decline in testosterone levels in ageing men is primarily influenced by comorbidities, without significant alterations in the genetic architecture of testosterone levels. Material and Methods: We included 6,406 men with baseline and follow-up measurements of circulating serum concentrations of total testosterone (T), bioavailable testosterone (BAT) and sex hormone-binding globulin (SHBG) representing an independent sub-cohort of the UK Biobank study. We 1) assessed the association of baseline levels with the decline in sex steroids and 2) developed and verified polygenic risk score (PRS) models for T, BAT and SHBG based on 183,909 men from the UK Biobank (sub cohorts: 70% base, 15% target and 15% validation, follow-up cohort excluded for PRS development). Results: In the follow-up sub cohort, mean age (SD) at baseline was 58.2 yrs ( 7.5) and mean (SD) follow-up period was 4.3 (1.0) yrs. Mean (SD) BAT at baseline were 5.2 (1.32) nmol/L with a mean (SD) decline of 1.6 (24.4) % at follow-up. Baseline BAT, T and SHBG levels were significantly associated with the relative change of the respective biomarker at follow-up (-7.8, -2.9 and -0.4% per nmol/L, respectively, all p &amp;lt;0.001). After correcting for age at baseline, follow-up period and principal components 1-10, PGSTestosterone and PGSBAT were not associated with relative decline of the respective biomarker (both p = n.s.). Conclusion: Our study did not find evidence supporting a genetic component in the age-related decline of circulating serum T or BAT concentrations. Instead, in accordance to previous observational studies, our results suggest that rather non-genetic factors, e.g. increasing incidence rates of comorbidities, drive the age-related decline in sex steroid levels in men. Our study contributes to understanding the intricate relationship between genetic and non-genetic factors with age-related testosterone decline in men and offers valuable insights for potential interventions targeting age-related hormonal changes and associated health outcomes. Presentation: 6/2/2024

8039 Role Of Genetics In The Age-Related Testosterone Decline In Men: A UK Biobank Study

Abstract Disclosure: L. Ogoniak: None. S. Sandmann: None. J. Varghese: None. A.S. Busch: None. Background: Age-related decline in circulating serum testosterone concentrations is a well-established phenomenon in men. While the decline is partially linked to comorbidities such as obesity, type 2 diabetes (T2D), and cardiovascular disease (CVD), healthy ageing men present with rather stable levels. Recent genetic mapping studies demonstrated a large influence of common genetic variation on testosterone levels in men. However, increasing incidence rates of comorbidities in the ageing population are posing a challenge for the disentanglement of effects. Objective: Our study aims to investigate the genetic component of age-dependent testosterone decline in men. We hypothesize that the decline in testosterone levels in ageing men is primarily influenced by comorbidities, without significant alterations in the genetic architecture of testosterone levels. Material and Methods: We included 6,406 men with baseline and follow-up measurements of circulating serum concentrations of total testosterone (T), bioavailable testosterone (BAT) and sex hormone-binding globulin (SHBG) representing an independent sub-cohort of the UK Biobank study. We 1) assessed the association of baseline levels with the decline in sex steroids and 2) developed and verified polygenic risk score (PRS) models for T, BAT and SHBG based on 183,909 men from the UK Biobank (sub cohorts: 70% base, 15% target and 15% validation, follow-up cohort excluded for PRS development). Results: In the follow-up sub cohort, mean age (SD) at baseline was 58.2 yrs ( 7.5) and mean (SD) follow-up period was 4.3 (1.0) yrs. Mean (SD) BAT at baseline were 5.2 (1.32) nmol/L with a mean (SD) decline of 1.6 (24.4) % at follow-up. Baseline BAT, T and SHBG levels were significantly associated with the relative change of the respective biomarker at follow-up (-7.8, -2.9 and -0.4% per nmol/L, respectively, all p &amp;lt;0.001). After correcting for age at baseline, follow-up period and principal components 1-10, PGSTestosterone and PGSBAT were not associated with relative decline of the respective biomarker (both p = n.s.). Conclusion: Our study did not find evidence supporting a genetic component in the age-related decline of circulating serum T or BAT concentrations. Instead, in accordance to previous observational studies, our results suggest that rather non-genetic factors, e.g. increasing incidence rates of comorbidities, drive the age-related decline in sex steroid levels in men. Our study contributes to understanding the intricate relationship between genetic and non-genetic factors with age-related testosterone decline in men and offers valuable insights for potential interventions targeting age-related hormonal changes and associated health outcomes. Presentation: 6/2/2024

9224 Evaluation of Safety and Efficacy of Administration of Estradiol by Subcutaneous Injection in Transgender Women

Abstract Disclosure: H. Perkins: None. H. Moreau: None. J. LaBudde: None. W. Craig: None. D.I. Spratt: None. Background: Off-label use of subcutaneous (SC) estradiol (E2) by transgender women for gender-affirming hormone therapy is becoming increasingly widespread, despite a lack of published data regarding its efficacy and safety. Methods: This retrospective cohort study used manual data extraction from electronic medical records for patients ages 18-79 years, currently or previously receiving oral (PO) 17-beta E2 or SC E2 valerate therapy at Maine Medical Center Reproductive Endocrinology and Infertility and Gender Clinics between 5/30/14-5/30/23, who completed E2 dose adjustments aimed at obtaining a serum E2 of 75-250 pg/mL. SC E2 was administered weekly and PO E2 daily. Serum testosterone (T), estrone (E1), and sex hormone binding globulin (SHBG) levels were recorded if drawn within 90 days of E2 measurement on an optimized dose. In a subset of patients receiving SC E2, serum E2 levels were drawn 1-2 days post- and pre-injection. All patient-reported local or systemic reactions were recorded. Data are expressed as median (full range) or mean ± standard deviation (full range). Results: 45 patients were included with no significant differences in demographics between PO (n=20) and SC (n=25) groups. Both groups achieved therapeutic E2 levels after dose adjustment without statistical difference in mean serum E2 (pg/mL) between SC and PO groups: 148.7 ± 41.0 (78-226) vs. 151.6 ± 31.7 (97-208); p=0.79 by t-test. In patients without orchiectomy, both SC and PO groups had T (ng/dL) suppressed to normal adult female range (10-55) in 11/12 SC patients and in 17/17 PO patients; median T was 14.0 (7.7-86) for SC vs. 20.6 (3.4-42) for PO; p=0.98 by Mann-Whitney U test. Median E2 dose (mg/week) in the SC group was 3.0 (1.4-6.0) and in the PO group was 42.0 (28-84). Median serum E1 (pg/mL) was lower in the SC group than the PO group: 73.5 (29-115), n=12 vs. 907 (596-1601), n=5, p&amp;lt;0.001 by Mann-Whitney U test. E1/E2 ratio was lower in the SC group than the PO group: 0.4 ± 0.1 vs. 8.0 ± 2.9; p&amp;lt;0.001 by t-test. There was no significant difference in median serum SHBG (nmol/L) between SC and PO groups: 71.7 (19.3-146.7), n=15 vs. 73.4 (51.0-187.4), n=14; p=0.20 by Mann-Whitney U test. Mean post- and pre-dose serum E2 levels in 5 patients were 138.0 ± 24.0 and 88.0 ± 57.6, respectively. There was one transient local reaction and no systemic allergic or inflammatory reactions in the SC group with no systemic reactions in the PO group. Conclusion: These results demonstrate that SC E2 at doses of 1.4-6 mg/week can be administered safely to achieve therapeutic serum E2 levels and suppress serum T levels to within the normal female range. Our preliminary data reveal lower serum E1 levels in the SC group than in the PO group suggesting reduced hepatic first-pass metabolism with SC administration; this pattern was not seen with serum SHBG levels. Post- and pre-dose serum E2 levels revealed only a mild decline in E2 levels between injections. Presentation: 6/3/2024

5116 Postmenopausal Hyperandrogenism due to Rare Ovarian Tumor

Abstract Disclosure: M. Salim: None. S. Dasaraju: None. Y. Lee: None. S. Afzal: None. B.K. Erickson: None. M.A. Khalifa: None. L.A. Burmeister: None. Background: Hyperandrogenism in postmenopausal women may arise from either ovarian or adrenal source and can pose challenging diagnostic dilemma. Clinical Case: A 66-year-old multigravida, post-menopausal woman presented with a 3-month history of worsening alopecia. Her past medical history included diabetes mellitus type 2 and breast cancer. Menarche was at age 12. There was no history of infertility. Menopause was in her 40’s. She had been shaving her upper lip and chin hair every 3 days for the past 10 years. Scalp hair loss had accelerated in the last 3 months, with loss of the bangs. Physical exam was significant for body mass index 34, deep voice, and clitoromegaly. Laboratory tests showed testosterone 160 ng/dL, (8-60 ng/dL), free testosterone 3.37 ng/dL (0.06-0.38 ng/dL), androstenedione 2.196 ng/mL (0.13-0.82 ng/mL), sex hormone binding globulin (SHBG) 31 nmol/L (30-135 nmol/L), dehydroepiandrosterone-sulfate (DHEAS) 86 ug/dL (13-130 ug/dL), 17-hydroxy progesterone 96 ng/dL (&amp;lt;51 ng/dL), inhibin A 1.1 pg/mL (&amp;lt;6.9 pg/mL), inhibin B &amp;lt;10 pg/mL (&amp;lt;16 pg/mL), adrenocorticotropic hormone 38 pg/mL (&amp;lt;47 pg/mL), and cortisol 12.2 ug/dL (4-22 ug/dL). Response to 1 mg overnight dexamethasone suppression test demonstrated persistently elevated testosterone (160 ng/dL), and incomplete suppression of androstenedione (0.827 ng/mL) and cortisol (2.4 ug/dL). Computerized tomography (CT) scan showed a left adrenal nodule (12 mm, 5 Hounsfield units, stable compared to imaging 2 years prior) and unremarkable appearance of the ovaries. Pelvic ultrasound did not show ovarian tumor on the right and left ovary was not seen. Adrenal and ovarian vein sampling suggested the ovaries as the source of the testosterone. Given the ovarian vein sampling results, a multidisciplinary discussion between endocrinology and gynecologic oncology concluded that bilateral salpingo-oophorectomy (BSO) was the next best step for diagnosis and management. Laparoscopic BSO was performed. Intraoperatively, the ovaries appeared grossly normal with the exception of dilated ovarian veins. Histopathology showed bilateral Leydig cell tumors (left: 1.5 cm; right: 2.0 cm) and a 0.7 cm left ovarian Brenner tumor. At 1-year postoperative follow-up, alopecia had resolved. Laboratory evaluation showed normalization of the testosterone (23 ng/dL), free testosterone (0.47 ng/dL). Androstenedione (1.023 ng/mL) was lower than before surgery but higher than reference range. Conclusion: The presented rare case of postmenopausal virilization is even more unique due to the synchronous presence of 2 rare ovarian tumors, both capable of causing hyperandrogenism, including bilateral ovarian Leydig cell tumor, Brenner tumor and adrenal incidentaloma. Despite normal appearing ovaries on imaging studies, BSO was ultimately necessary for diagnosis and management. Presentation: 6/3/2024

6983 Pembrolizimab Induced Hypophysitis: Uncommon Side Effect Leading To Late Diagnosis

Abstract Disclosure: T. Chaudhary: None. O. Syed: None. A. Shridar: None. R. Kaur: None. O. Chaudhary: None. M.S. Zubair: None. Background: Pembrolizumab, an immune checkpoint inhibitor, has shown efficacy inducing remission in various malignancies. Associated immune-related adverse effects (irAEs) have been recorded but cases of concomitant hypophysitis and thyroiditis are rare. Clinical case: The patient is a 41-year-old male with a past medical history significant for metastatic melanoma of the left calf, status post sentinel lymph node biopsy and left inguinal lymph node dissection, treated with pembrolizumab for one year. He initially presented with a severe headache that was preceded by two months of fatigue and impaired concentration. CT and MRI head were both unremarkable while lab work was significant for cortisol 0.2 ug/dL and adrenocorticotropic hormone (ACTH) 1.1 pmol/L. A full hormone panel was ordered which showed normal insulin-like growth factor-1 (IGF-1), luteinizing hormone (LH), and follicle-stimulating hormone (FSH). Free testosterone was at the lower end of normal. Prolactin was elevated at 27.3 ng/mL. The thyroid function tests showed primary hypothyroidism with elevated thyroid stimulating hormone (TSH) at 109 uIU/mL, low T4 at 1.5 ug/dL, and low free T4 at 0.4 ng/dL. There were no signs or symptoms of posterior pituitary dysfunction. The patient was diagnosed with hypophysitis and started on hydrocortisone 20 mg once daily along with levothyroxine 175 mcg once daily. DEXA scan showed normal bone mineral density. Subsequently, the patient presented to our care and reported symptom improvement after taking the prescribed medication however he continued to develop fatigue by the end of the day. Therefore, hydrocortisone prescription was switched to 15 mg in the morning and 10 mg at noon. A repeat thyroid function panel, sex hormone binding globulin, and LH were ordered, to be followed up at the patient's next visit. The patient was also advised to wear a medical alert bracelet at all times moving forward. Conclusion: Due to non-specific symptoms at onset, hypophysitis can be undiagnosed or misdiagnosed therefore it is important to have a high clinical suspicion with patients on PD-1 inhibitors presenting with such symptoms. It is also imperative to order a full set of hormones as this patient had concomitant primary hypothyroidism. Presentation: 6/1/2024