Free T Research Articles

The Relative Contributions of Aging, Health, and Lifestyle Factors to Serum Testosterone Decline in Men

Although it is known that serum testosterone (T) concentrations decline with age, the relative contributions of changes in health and lifestyle to that decline have not been adequately assessed. The objective of this study was to establish the relative importance of aging, health, and lifestyle in contributing to male T decline. A prospective cohort study of health and endocrine functioning in randomly selected men with a baseline visit (T1, 1987-1989) and two follow-up visits (T2, 1995-1997; T3, 2002-2004) was conducted. An observational study of men residing in greater Boston, Massachusetts, was conducted. Participants included 1667 men aged 40 to 70 at baseline; follow-up was conducted on 947 (57%) and 584 (35%) at T2 and T3, respectively. Main outcome measures included total serum T, calculated free T (FT), and SHBG. There were substantial declines in total serum T and FT levels associated with aging alone. However, many health and lifestyle changes were associated with accelerated decline. A 4- to 5-kg/m2 increase in body mass index or loss of spouse was associated with declines in total serum T comparable to that associated with approximately 10 yr of aging. Results were similar for FT, but fewer factors were associated with SHBG after age was taken into account. Both chronological aging and changes in health and lifestyle factors are associated with declines in serum T. Comorbidities and lifestyle influences may be as strongly associated with declining T levels as is aging itself over the short- to midterm. These results suggest the possibility that age-related hormone decline may be decelerated through the management of health and lifestyle factors.

Assessment of Insulin Resistance in the Idiopathic Hirsutism

Background: Idiopathic hirsutism (IH) is the second most common cause of hirsutism, after polycystic ovary syndrome and occurs in about 15% of hirsute women. There are not many studies showing whether patients with IH also have insulin resistance. In the present study, we aimed to investigate the insulin sensivity in IH with non-obese and changing hormone levels during the hyperinsulinemic-euglycemic clamp. Methods: Twenty (20) non-obese women with IH (Group I) ranging in age from 20 to 30 (mean 25 ± 5) years were studied. Hirsutism in women with normal testosterone (T) levels and regular menstrual cycles is as defined IH. Twenty (20) healthy women (mean age 23 ± 2 years) (Group II) were included in this study as the control group. Insulin sensitivity was assessed with modified euglycemic insulin clamp technique. Samples of prolactin, luteinizing hormone (LH), follicle-stimulating hormone, adrenocorticotropic hormone (ACTH), dehydroepiandrosterone sulfate, cortisol, estradiol, progesterone, 17-OH progesterone (17-OHP), total T, and free T (FT) were obtained at baseline and at 2nd hour during clamp. Results: Steady-state (120 min) glucose disposal rates were higher in Group II than Group I (7.51 ± 0.83 vs. 5.76 ± 1.89 mg/kg/min). Mean FT, ACTH, cortisol, LH, prolactin and 17-OHP levels were found to have decreased statistically significantly (p < 0.05) in Group I. Mean FT, ACTH, and prolactin levels were found to have decreased statistically significantly (p < 0.05) in Group II during the clamp. Mean baseline levels of FT, LH and prolactin were greater in women with hirsutism than in the control subjects (p < 0.05). Insulin mediated glucose disposal was lower in the normal weight women with IH than in those without hirsutism. Conclusions: Mean FT, 17-OHP and dehydroepiandrosterone sulfate levels decreased during euglcemic-hyperinsulinemic clamp in IH.

Free Testosterone is an Independent Predictor of BMD and Prevalent Fractures in Elderly Men: MrOS Sweden

The role of androgens for bone health in elderly men is unclear. We show that free testosterone within the normal range is a predictor of BMD at predominantly cortical bone sites and of previous osteoporosis-related fractures in elderly Swedish men. Osteoporosis-related fractures constitute a major health concern not only in women but also in men. Previous studies have clearly shown that serum levels of estradiol are associated with BMD, whereas more conflicting data have been presented regarding the predictive value of testosterone (T) for bone health in elderly men. The aim of this study was to investigate if serum levels of T are associated with BMD and/or prevalent fractures in a large cohort of elderly men. In the Swedish part of the MrOS study (n = 2908; average age, 75.4 years), bone parameters were measured using DXA, and prevalent fractures were recorded using standardized questionnaires and by vertebral X-ray analyses. Serum levels of total T, total estradiol (E2), and sex hormone-binding globulin (SHBG) were measured by radioimmunoassay, and free T (FT) and free E2 (FE2) were derived from the mass action equations. Height, weight, age, physical activity, smoking habits, and calcium intake were included together with FT and FE2 in regression models for BMD. FT was an independent positive predictor of BMD in total body, total hip, femur trochanter, and arm but not in the lumbar spine. The highest independent predictive value of FT was found in the arm and the hip (with a relatively high content of cortical bone). FE2 was an independent predictor of BMD at all bone sites studied, and the highest predictive value was seen for lumbar spine (with relatively high content of trabecular bone) BMD. FT but not FE2 was a positive predictor of total body bone area and BMC. FT levels below the median were independent predictors of prevalent osteoporosis-related fractures (OR, 1.56; 95% CI, 1.14-2.14; p < 0.01) and X-ray-verified vertebral fractures (OR, 2.00; 95% CI, 1.34-2.86; p < 0.001). The predictive value of FT for prevalent fractures was not affected by adjustment for BMD. These findings show that variation of FT within the normal range is an independent but modest predictor of BMD at predominantly cortical bone sites and of previous osteoporosis-related fractures in elderly men. Our data indicate that not only estrogens but also androgens are of importance for bone health in elderly men. Longitudinal studies investigating the predictive value of T for fracture risk in elderly men are required.

Sildenafil improves sexual functioning in premenopausal women with type 1 diabetes who are affected by sexual arousal disorder: a double-blind, crossover, placebo-controlled pilot study

To verify whether sildenafil is effective in type 1 premenopausal women affected by sexual arousal disorder (SAD). Double-blind, crossover, placebo-controlled study. Gynecological diabetic outpatient clinic and sexual clinic. Thirty-six type 1 premenopausal diabetic women affected by SAD. Two 8-week periods of sildenafil 100 mg, washout, and placebo, by two possible sequences. Each woman submitted blood samples to measure HbA(1c), and T, free T (FT), and PRL. Efficacy was assessed [1] subjectively by the Personal Experiences Questionnaire based on the 5-point Likert scale, quantifying arousal, desire, orgasm, enjoyment of sexual activities, and frequency of sexual relationships; and [2] objectively by translabial color Doppler ultrasound to measure the resistance index (RI), pulsatility index (PI), peak systolic velocity (PSV), and end diastolic velocity of clitoral arteries. Thirty-two women completed the study. The mean HbA(1c) value was 8.0% +/- 1.8%, and plasma concentrations of T, FT, and PRL were normal. Sildenafil seems to improve arousal, orgasm and sexual enjoyment, and dyspareunia in women affected by type 1 diabetes. However, by flowmetric measurements, the mean RI was significantly lower and both the mean PI and PSV of the clitoral arteries were significantly higher compared with baseline and placebo. Sildenafil seems to improve subjective sexual aspects and can be used to treat objectively genital arousal disorder of premenopausal women with type 1 diabetes.

Frequent Occurrence of Hypogonadotropic Hypogonadism in Type 2 Diabetes

Type 2 diabetes is associated with lower total testosterone (T) levels in cross-sectional studies. However, it is not known whether the defect is primary or secondary. We investigated the prevalence of hypogonadism in type 2 diabetes by measuring serum total T, free T (FT), SHBG, LH, FSH, and prolactin (PRL) in 103 type 2 diabetes patients. FT was measured by equilibrium dialysis. FT was also calculated by using T and SHBG (cFT). Hypogonadism was defined as low FT or cFT. The mean age was 54.7 +/- 1.1 yr, mean body mass index (BMI) was 33.4 +/- 0.8 kg/m(2), and mean HbA1c was 8.4 +/- 0.2%. The mean T was 12.19 +/- 0.50 nmol/liter (351.7 +/- 14.4 ng/dl), SHBG was 27.89 +/- 1.65 nmol/liter, and FT was 0.250 +/- 0.014 nmol/liter. Thirty-three percent of patients were hypogonadal. LH and FSH levels were significantly lower in the hypogonadal group compared with patients with normal FT levels (3.15 +/- 0.26 vs. 3.91 +/- 0.24 mIU/ml for LH and 4.25 +/- 0.45 vs. 5.53 +/- 0.40 mIU/ml for FSH; P < 0.05). There was a significant inverse correlation of BMI with FT (r = -0.382; P < 0.01) and T (r = -0.327; P < 0.01). SHBG correlated inversely with BMI (r = -0.267; P < 0.05) but positively with age (r = 0.538; P < 0.001) and T (r = 0.574; P < 0.001). FT correlated strongly with cFT (r = 0.919; P < 0.001) but not with SHBG. LH levels correlated positively with FT (r = 0.287; P < 0.05). We conclude that hypogonadotropic hypogonadism occurs commonly in type 2 diabetes.

Perturbed sex steroid status in men with idiopathic osteoporosis and their sons.

We reported previously that a gender-specific defect of acquisition of lumbar bone mass plays an important role in the pathogenesis of male idiopathic osteoporosis (IO) and that there is a strong heritability of this maturational defect, which is particularly manifest in sons of men with IO. A hypothetical role of an altered sex steroid status and/or of a (TTTA)(n)- repeat polymorphism of the aromatase (CYP19) gene in male IO remains to be established. We evaluated bone mineral density (BMD) at the lumbar spine and femoral neck in 64 male IO probands (selected on the basis of a z-score of -2 or less), 21 of their sons, 41 of their brothers, and 126 healthy, age-matched controls. Serum testosterone (T), estradiol (E(2)), and SHBG levels were measured by immunoassays. Free T (FT) and free E(2) (FE(2)) levels were calculated from total T, E(2), SHBG, and albumin concentrations using a previously validated equation. Probands, sons, and brothers had lower body weight than age-matched controls, with mean differences of 5.0, 4.6, and 4.0 kg, respectively. In probands, sons, and brothers, SHBG levels were higher compared with controls. Significantly lower FE(2) levels were observed in probands and sons compared with their respective controls (P < 0.05 and P < 0.01, respectively). The brothers had nonsignificantly lower FE(2) levels compared with their controls. In the total group of sons with significantly lower FE(2) levels, tertile analysis according to lumbar spine BMD showed that only in the subgroup of sons belonging to the lowest tertile both FE(2) and FT were decreased compared with their controls. The differences in FE(2) levels in IO probands and their sons remained significant after adjustment for body mass index (BMI), even though in multivariate analyses BMI was a major determinant of BMD. The frequency distribution of the CYP19 gene (TTTA)(n)- repeat length (determined by fragment analysis, GeneScan) was not different between men with IO and their controls. In conclusion, the finding of a relative FE(2) deficit in both men with IO as well as their affected sons, even after adjustment for BMI, suggests that estrogen-related perturbances may be involved in the pathogenesis of the deficient acquisition of peak bone mass in male IO.

Differential contribution of testosterone and estradiol in the determination of cholesterol and lipoprotein profile in healthy middle-aged men

The role of endogenous sex steroids in the association between male gender and cardiovascular risk remains unclear. We performed a cross-sectional analysis of the role of endogenous testosterone (T) and estradiol (E 2), as well as their respective biologically active fractions, in the determination of lipids and lipoproteins in an occupation-based cohort of 715 healthy middle-aged men. Serum T, sex hormone binding globulin (SHBG) and E 2 were measured by immunoassays; free T (FT) and free E 2 (FE 2) were calculated using a validated equation. Serum total cholesterol (Chol), HDL-cholesterol (HDL-Chol), apolipoproteins A1 (ApoA1), B (ApoB), E (ApoE), ApoE phenotype, lipoprotein a (Lpa), fibrinogen, C-reactive protein (CRP), systolic (SBP) and diastolic blood pressure (DBP) were assessed. Serum levels of T and FT, correlated positively with HDL-Chol and ApoA1 with Spearman correlation coefficients, partialised for age and body mass index (BMI), ranging between 0.14 and 0.17 ( P<0.001); FT was associated with total Chol and ApoB levels ( r=0.12 for both T and FT; P<0.01). After adjustment for age and BMI, both serum E 2 and FE 2 levels correlated significantly with ApoE ( r=0.25 and r=0.26 for E 2 and FE 2, respectively; P<0.001). Free and total E 2 were associated with both SBP and DBP with correlation coefficients partialised for age and BMI ranging between 0.11 and 0.13 ( P<0.01). No correlation was found between any of the studied sex steroids, fibrinogen, Lpa or CRP. In multiple linear regression analyses, T was the most important independent hormonal determinant of HDL-Chol levels, when E 2, SHBG and exogenous factors were considered in the model ( P<0.01), whereas E 2 contributed mostly in the determination of ApoE levels ( P<0.001) and SBP ( P<0.01). When FT and FE 2 were considered in multivariate analyses as independent hormonal variables, FT was the most significant predictor of HDL-Chol ( P<0.01) and ApoB ( P<0.01) concentrations. Moreover, in the same multivariate model, ApoE ( P<0.001) concentration as well as SBP ( P<0.001) was most affected by FE 2 levels in comparison with FT. In conclusion, our findings do suggest a differential role of T and E 2 in the determination of traditional cardiovascular risk factors in healthy middle-aged men. In the determination of both HDL-Chol and ApoB levels endogenous (F)T may be involved, whereas (F)E 2 may contribute to the determination of ApoE levels in this study group of 715 healthy middle-aged men. Regarding the observational design of the study, the physiological relationship of the observed associations between sex steroids and cardiovascular risk factors remains to be unravelled.

GH-IGF-I axis in non-obese women with functional hyperandrogenism.

The study was conducted to assess the GH-IGF-I axis in non-obese women with functional hyperandrogenism (FH). Eighteen FH women aged 18-35 yr with a body weight within 20% of ideal body weight and 10 weight-matched controls were included in the study. Basal serum GH, GH-binding protein (GHBP), IGF-I, IGF-binding protein-3 (IGFBP-3) levels were determined as well as GH levels during GHRH stimulation. In addition, basal serum androgens [free T (FT), delta4 and DHEAS], insulin and glucose levels were determined. The group of non-obese patients with FH differed from controls in GHBP (1.21+/-0.37 vs 0.93+/-0.25 nmol/l; p<0.05) and androgen levels (FT: 8.0+/-3.2 vs 1.9+/-1.2 pmol/l, p<0.001; delta4: 10.5+/-3.2 vs 5.9+/-2.1 nmol/l, p<0.001; DHEAS: 9.3+/-3.0 vs 5.1+/-1.8 micromol/l, p<0.001). GH (r=0.365; p<0.05) and IGF-I (r=0.508, p<0.01) serum levels were significantly correlated to serum DHEAS levels in a combined group of patients and controls. Our results support the suggestion that the GH-IGF-I axis plays an important role in the evolution of hormonal and metabolic derangement in non-obese FH women.

Role of the follistatin gene in women with polycystic ovary syndrome

Objective: To search for mutations in the coding exons of the follistatin gene of women diagnosed with polycystic ovary syndrome (PCOS). Design: Controlled clinical study. Setting: Tertiary institutional hospital. Patient(s): Thirty-four women diagnosed with PCOS and 15 healthy control women. Intervention(s): Whole blood and serum samples were collected during the follicular phase of the menstrual cycle. Main Outcome Measure(s): Circulating total testosterone (T), sex hormone–binding globulin (SHBG), calculated free T (FT), androstenedione (A), dehydroepiandrosterone-sulfate (DHEAS), LH, FSH, E 2, and basal and adenocorticotropic hormone (ACTH)-stimulated 17-hydroxyprogesterone (17-OHP) were determined. Insulin resistance was estimated from fasting glucose and insulin levels, using the homeostasis model assessment. The coding regions of the follistatin gene were studied by heteroduplex analysis after polymerase chain reaction amplification. Result(s): Women with PCOS presented with higher body-mass index, insulin resistance, T, FT, A, and ACTH-stimulated 17-OHP serum concentrations and lower SHBG serum levels, as compared with controls. No differences were observed among the groups in serum DHEAS, basal 17-OHP, E 2, LH, and FSH. No mutations were found in coding regions of the follistatin gene, with the exception of a G to A change at cDNA position 951, resulting in a silent mutation. This change was present in 2 (5.9%) of 34 patients and 1 (6.7%) of 15 controls. Conclusion(s): Mutations in the coding regions of the follistatin gene do not appear to be related to PCOS.

Measures of Bioavailable Serum Testosterone and Estradiol and Their Relationships with Muscle Strength, Bone Density, and Body Composition in Elderly Men*

In the present cross-sectional study of 403 independently living elderly men, we tested the hypothesis that the decreases in bone mass, body composition, and muscle strength with age are related to the fall in circulating endogenous testosterone (T) and estrogen concentrations. We compared various measures of the level of bioactive androgen and estrogen to which tissues are exposed. After exclusion of subjects with severe mobility problems and signs of dementia, 403 healthy men (age, 73-94 yr) were randomly selected from a population-based sample. Total T (TT), free T (FT), estrone (E1), estradiol (E2), and sex hormone-binding globulin (SHBG) were determined by RIA. Levels of non-SHBG-bound T (non-SHBG-T), FT (calc-FT), the TT/SHBG ratio, non-SHBG-bound E2, and free E2 were calculated. Physical characteristics of aging included muscle strength measured using dynamometry, total body bone mineral density (BMD), hip BMD, and body composition, including lean mass and fat mass, measured by dual-energy x-ray absorptiometry. In this population of healthy elderly men, calc-FT, non-SHBG-T, E1, and E2 (total, free, and non-SHBG bound) decreased significantly with age. T (total and non-SHBG-T) was positively related with muscle strength and total body BMD (for non-SHBG-T, respectively, beta = 1.93 +/- 0.52, P < 0.001 and beta = 0.011 +/- 0.002, P < 0.001). An inverse association existed between T and fat mass (beta = -0.53 +/- 0.15, P < 0.001). Non-SHBG-T and calc-FT were more strongly related to muscle strength, BMD, and fat mass than TT and were also significantly related to hip BMD. E1 and E2 were both positively, independently associated with BMD (for E2, beta = 0.21 +/- 0.08, P < 0.01). Non-SHBG-bound E2 was slightly strongly related to BMD than total E2. The positive relation between T and BMD was independent of E2. E1 and E2 were not related with muscle strength or body composition. In summary, bioavailable T, E1, total E2, and bioavailable E2 all decrease with age in healthy old men. In this cross-sectional study in healthy elderly men, non-SHBG-bound T seems to be the best parameter for serum levels of bioactive T, which seems to play a direct role in the various physiological changes that occur during aging. A positive relation with muscle strength and BMD and a negative relation with fat mass was found. In addition, both serum E1 and E2 seem to play a role in the age-related bone loss in elderly men, although the cross-sectional nature of the study precludes a definitive conclusion. Non-SHBG-bound E2 seems to be the best parameter of serum bioactive E2 in describing its positive relation with BMD.

Serum testosterone fractions in women: Normal and abnormal clinical states

The potential usefulness of determining serum testosterone (T) fractions in women, ie, sex hormone-binding globulin (SHBG)-bound T, albumin-bound T (Alb-T), and free T (FT) fractions, was explored in a variety of clinical situations. Serum T, SHBG, and albumin concentrations were measured by standardized methods and using binding constants of T to SHBG and albumin, we calculated serum T fractions, which agreed remarkably with measured values of SHBG-T and nonbound T. Serum T levels did not change in normal women examined during the follicular and luteal phases of the menstrual cycle, but SHBG levels were elevated in the luteal phase, changing the distribution of T, with increased SHBG-T and less T distributed to other fractions. Women taking oral contraceptives had decreased serum T levels, but use of androgen-like oral contraceptives decreased SHBG levels and T distribution to this binding protein, whereas use of non-androgen-like oral contraceptives increased SHBG levels, resulting in the expected shift of T fractions. Women receiving phenytoin for seizure disorders and women with Graves' disease exhibited increased SHBG levels with concomitant increased SHBG-T and decreased distribution of T to nonbound fractions. Women with hirsutism exhibited decreased SHBG levels irrespective of total serum T levels, and the T SHBG ratio was elevated in this population. However, of interest were women with morbid obesity (nonhirsute) who had similar low levels of SHBG and T SHBG ratios that were indistinguishable from those of hirsute women. Determination of T fractions may provide a more useful clinical tool in evaluating hirsute women than simple measurement of serum T levels, although at present, T fractionation studies are not useful indicators of hyperandrogenism when morbid obesity is coexistent.

Diet and plasma androgens in postmenopausal vegetarian and omnivorous women and postmenopausal women with breast cancer

We studied 27 postmenopausal women, 9 vegetarians, 10 omnivores, and 8 apparently healthy women with breast cancer (BC), four times during 1 y. Dietary intakes were recorded and plasma androgens and sex-hormone-binding globulin (SHBG) binding capacity were determined. Androstenedione (A), testosterone (T), free T (FT), and SHBG were higher in omnivores than in vegetarians. In multiple correlation analysis, intakes of protein and fat were positively correlated with A, T, and FT, whereas the intakes of carbohydrate, grain, total fiber, and grain fiber showed the opposite correlations. Protein intake was positively correlated with percentage FT (%FT) and negatively with SHBG. BC patients had a similar pattern to omnivores with even higher levels of A and T (significant compared with vegetarians) and they showed significantly higher FT and lower SHBG than both control groups. We conclude that a Western-type diet in postmenopausal women is associated with high A, T, %FT, FT, and low SHBG and this pattern was apparent in the BC patients.

Decreased bioavailable testosterone in aging normal and impotent men.

Tissue available (bioavailable) testosterone (T) includes circulating free T (FT) and albumin-bound T. A reasonable assessment of bioavailable T can be made by using 50% ammonium sulfate to precipitate sex hormone-binding globulin (SHBG)-bound T. The supernatant non-SHBG-bound T (non-SHBG-T) correlates well with physiological androgen activity. To assess bioavailable T in normal aging men, we analyzed serum samples from seven healthy aged men (65-83 yr old) and compared the results to samples from 13 young men (22-39 yr old). Mean serum T, FT, and LH concentrations were not significantly different in the 2 groups. However, the mean absolute non-SHBG-T level was significantly lower (P less than 0.005) in the older group. In a separate population of 20 impotent but otherwise healthy men (5 27-37 yr old, 10 48-64 yr old, and 5 66-69 yr old), the mean absolute non-SHBG-T concentration was lower in middle-aged (P less than .01) and elderly men (P less than 0.001) than in young men. The absolute FT was lower only in the elderly group (P less than 0.05), while mean LH and T levels were similar in all 3 age groups. These data suggest that serum concentrations of tissue available T are decreased in aged men and that non-SHBG-T measurement is a more sensitive indicator of this decrease than are serum T or serum FT measurements. These changes appear to begin by middle age.