TRH Test Research Articles

The effects of cannabidiol on immune function and health parameters in senior horses

Cannabidiol (CBD) has potential to reduce pain and inflammation in humans leading to the interest of use in equine. The purpose of this study was to determine the effects of CBD on immune function by measuring inflammatory cytokines and antibody responses to vaccination, as well as other health parameters in senior horses. Horses were orally-dosed with CBD (2 mg/kg: 13 horses) or control (soy oil: 14 horses) daily for 90 days, from July 2021 to November 2021. Peripheral blood samples were collected on days 0, 30, 60, and 90 before administering treatments. On day 90 all horses were kept on treatment and vaccinated with an equine influenza vaccine and blood samples were collected post-vaccination on days 14 and 21. For all time points, plasma samples were analyzed for determination of CBD and metabolites, 7-OH CBD and 7-COOH CBD, using tandem mass spectrometry. For time points 0, 30, 60 and 90, blood samples were analyzed for CBC and chemistry. Additionally, peripheral blood mononuclear cells (PBMC) were isolated, stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin, stained intracellularly for interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) then analyzed via flow cytometry. Real-time PCR (RT-PCR) analyzed both stimulated PBMCs and whole blood for cytokine gene expression. Inflammatory proteins C-reactive protein, interleukin 1 receptor agonist, and prostaglandin E2 were measured with equine-specific enzyme linked immunosorbent assays. Thyrotropin-releasing hormone stimulation test and oral sugar test were performed on all horses before and after the study to analyze metabolic function. Hemagglutination inhibition (HI) titers were measured for immune responses pre- and post-vaccination. All data were analyzed using either a paired t-test or a two-way repeated measures analysis of variance (significance P < 0.05). Plasma concentrations of CBD and metabolites were determined with 7-COOH CBD, the most significant metabolite, in CBD treated horses compared to control treated horses. A significant decrease was determined for whole blood inflammatory cytokine expression of IFN-γ at day 60, and for IL6 at day 60 and 90 for CBD-treated horses when compared to control horses. CBD did not significantly affect any other immune factors, HI titers, or health parameters. This study demonstrated that treatment with CBD reduced some inflammatory cytokine production with no negative side effects as measured by CBC or chemistry profiles. This study reveals the initial understanding of CBD in the horse, however more in-depth research is needed to fully understand its efficacy on the health of the horse.

Utility of basal and peak TSH values in TRH stimulation testing for predicting the long-term therapeutic prognosis of primary congenital hypothyroidism.

In Japan, most neonates undergo screening for congenital hypothyroidism (CH). A TRH stimulation test (TRH-T) may be performed after initial treatment as a useful method for reevaluating the patient's thyroid status. However, no studies have compared basal and peak TSH values in TRH-T in patients with long-term follow-up. This was a retrospective and observational study. The inclusion criteria were as follows: (1) CH diagnosis based on positive newborn screening, (2) follow-up > 15 yr, and (3) TRH-T after LT4 discontinuation. The participants were divided into a no-treatment group (No-T group) and a treatment group (T group). The No-T and T groups included 14 and nine patients, respectively. The age at TRH-T was 5.38 yr for the No-T group and 4.25 yr for the T group, with no significant difference. The basal and peak TSH levels were significantly lower in the No-T group. The areas under the Receiver operating characteristic curve for basal and peak TSH values were 0.984 and 0.905, respectively. When the basal TSH level was under 4.594 IU/mL, the No-T group had a sensitivity of 1.00 and a specificity of 0.93. Basal TSH levels alone may be sufficient for predicting the long-term therapeutic prognosis of patients with CH.

PSAT251 Examination of TRH test in Central Hypothyroidism due to Non-Functional Pituitary Adenoma

Abstract Objectives There is a little evidence for the TRH test criteria in the diagnosis of Central Hypothyroidism (CeH). Therefore, we investigated the significance of the TRH test for Central Hypothyroidism due to Non-Functional Pituitary Adenoma. Methods 107 cases of Non-functional pituitary adenoma (NFPA) in Gunma University Hospital Neurosurgery and Toranomon Hospital Intercerebral Pituitary Surgery, between 2007 to 2020 are studied. Subjects divided into CeH group (n = 19) with FT4 below the reference value and a normal group (n = 88). Serum TSH level was determined before (basal-TSH value) and 30, 60, 120 minutes after TRH administration. Peak-TSH value, delayed and prolonged responses were analyzed. A peak-TSH occurring at 60 minutes or later was considered as a delayed response. If 120-minutes TSH value to peak-TSH value ratio is equal to or higher than 0.6 was considered as a prolonged response. Results The basal-TSH was higher in the CeH group than in the normal group (median 2.7 vs. 1.5μIU/mL) (p &amp;lt;0.01). There was no difference between two groups, in both 30-minute value and the peak value. Delayed response occurred in 10/19 (53%) in the CeH group, and 18/88 (20%) in the normal group (p &amp;lt; 0.01). Prolonged response occurred at a higher rate of 15/19 (79%) in the CeH group, while in 23/88 (26%) in the normal group (p &amp;lt;0.01). AUC was maximum when prolonged response (120-minute value to peak value ratio) is equal to or lower than 0.65. Conclusion In central hypothyroidism due to Non-Functional Pituitary Adenoma, the basal-TSH value does not usually decrease, but rather be higher value within the reference range. 30-minute value or peak value was not useful in diagnosis, yet the prolonged response was more significant. Central Hypothyroidism in Non-Functional Pituitary Adenoma, can be diagnosed with sensitivity of 79% and specificity of 78% when the 120-minute value to peak value ratio is equal to or lower than 0.65. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Dopamine Function and Hypothalamic-Pituitary-Thyroid Axis Activity in Major Depressed Patients with Suicidal Behavior.

Involvement of the dopaminergic (DA) and hypothalamic-pituitary-thyroid (HPT) systems in suicidal behavior is still poorly understood. We assessed multihormonal responses to apomorphine (APO; a short acting DA receptor agonist) and 8 AM and 11 PM protirelin (TRH) tests in 30 medication-free DSM-5 euthyroid major depressed inpatients with suicidal behavior disorder (SBD) (current, n = 14; in early remission, n = 16) and 18 healthy hospitalized control subjects (HCs). Compared to HCs, responses to APO and TRH tests were unaltered in SBDs in early remission. However, current SBDs exhibited increased APO-induced growth hormone (GH) and adrenocorticotropin (ACTH) stimulation, and reduced 11 PM thyrotropin (TSH) and ∆∆TSH values (difference between 11 PM and 8 AM TRH-TSH responses). In current SBDs, the association between high APO-GH concentrations and low ∆∆TSH values was more common in recent suicide attempters than in past suicide attempters. These preliminary results suggest that co-occurring alterations in the DA and HPT systems (i.e., DA receptor hyperresponsiveness associated with decreased hypothalamic TRH drive) may contribute to the pathophysiology of suicidal behavior. Conversely, normalization of DA and TRH functions might reflect a process of recovery from suicidality. Thus, our findings suggest that drugs targeting the DAergic and TRH systems could be relevant in suicide prevention.

The effect of pergolide mesylate on adrenocorticotrophic hormone responses to exogenous thyrotropin releasing hormone in horses

Thyrotropin releasing hormone (TRH) stimulation testing is often used to support a diagnosis of pituitary pars intermedia dysfunction (PPID) in horses although it is unclear whether or not repeat TRH stimulation testing post-treatment is a valid means of assessing response to medical therapy. Laboratory submissions from 64 suspected equine PPID cases were examined including the initial pre-treatment TRH stimulation test and a follow up test within 100 days of starting medical therapy with pergolide. In a subset of cases, further follow-up tests were examined beyond 100 days of starting treatment. Results from tests conducted between 1 July and 30 November were excluded.Significant improvements were seen in both the baseline and TRH-stimulated adrenocorticotrophic hormone (ACTH) concentrations within 100 days with no further improvements seen in the subset of cases examined thereafter. Although 88% (n = 56/64) of all cases showed a decreased response to TRH post-treatment, only 24% (n = 9/38) of horses with positive pre-treatment TRH stimulation tests normalised following treatment, with a further 34% (n = 13/38) improving into an equivocal test outcome category. Most commonly (42%; n = 16/38), horses with positive pre-treatment TRH stimulation tests remained positive following treatment, although 75% (n = 12/16) of these showed a numerically lower post-treatment response to TRH. These results will help inform practitioners of expected changes in TRH stimulation test results when assessing response of horses with PPID to medical therapy with pergolide.

Effect of early or late blood sampling on thyrotropin releasing hormone stimulation test results in horses.

BackgroundDiagnosis of pituitary pars intermedia dysfunction (PPID) using the thyrotropin‐releasing hormone (TRH) stimulation test requires blood collection 10 minutes after TRH injection; it is unknown if small differences in timing affect test results.ObjectiveTo determine whether early or late sampling results in a significant (≥10%) difference in plasma adrenocorticotropic hormone (ACTH) concentration compared to standard 10‐minute sampling.AnimalsTwenty‐four healthy adult horses with unknown PPID status.MethodsIn this prospective study, subjects underwent a single TRH stimulation test, with blood collected exactly 9 minutes (early), 10 minutes (standard), and 11 minutes (late) after injection. ACTH was measured by chemiluminescent immunoassay. Two aliquots of the 10‐minute plasma sample were analyzed separately to assess intra‐assay variability. Data were reported descriptively and bias was calculated using Bland‐Altman plots. Significance was set at P = .05.ResultsMinor variability was observed between the paired 10‐minute sample aliquots (range, 0%‐6%; median 3%). Overall variability of early or late samples compared to the corresponding paired (average) 10‐minute standard concentration ranged from 0% to 92% (median 10%). Seventy‐five percent of horses (18/24) tested had at least 1 early or late reading that differed by ≥10% from its corresponding 10‐minute standard concentration, and 21% of horses (5/24) would have a different interpretation of testing result with either early or late sampling. Incidence of ≥10% variability was independent of PPID status (P = .59).Conclusions and Clinical ImportancePrecise timing of sample collection is critical to ensure accurate assessment of PPID status given the observation of significant variability associated with minor alterations in timing of sample collection.

Bexarotene-induced central hypothyroidism assessed by TRH stimulation test in cutaneous T-cell lymphoma patients.

Bexarotene-induced central hypothyroidism (CH), for which levothyroxine (LT4) replacement is recommended, has been shown to be caused by pituitary but not hypothalamic disorder experimentally, though the underlying mechanism in humans remains unclear. Here, the pathophysiology of bexarotene-induced CH was examined using a TRH stimulation test in cutaneous T-cell lymphoma (CTCL) patients. In this retrospective longitudinal observational study, serum TSH and free T4 (F-T4) levels were measured in 10 euthyroid patients with CTCL during 24 weeks of bexarotene treatment. TRH stimulation testing was performed following CH diagnosis, with LT4 replacement dosage adjusted to maintain F-T4 at the pre-treatment level. After one week of bexarotene administration, all 10 patients developed CH, based on combined findings of low or low-normal F-T4 with low or normal TSH levels. TSH peak response after a stimulation test at one week was reached at 30 minutes. However, that was <4 μIU/mL in all patients, indicating a blunted though not exaggerated and delayed TSH response. In eight who continued bexarotene for 24 weeks, median LT4 replacement dosage was 125 (range, 75-150) μg/day. TSH level at 30 as well as 15, 60, 90, and 120 minutes after TRH stimulation was significantly correlated with LT4 replacement dosage (ρ = -0.913, p = 0.002), whereas TSH and F-T4 basal levels at one week were not. These results suggest that pituitary hypothyroidism is responsible for bexarotene-induced CH, while TSH levels after TRH stimulation precisely reflect residual pituitary-thyroid function in patients receiving bexarotene.

Repeatability of a thyrotropin-releasing hormone stimulation test for diagnosis of pituitary pars intermedia dysfunction in mature horses.

BackgroundPituitary pars intermedia dysfunction (PPID) is a common endocrinopathy of horses diagnosed with a thyrotropin‐releasing hormone (TRH) stimulation test.Hypothesis/ObjectivesDescribe the repeatability of TRH stimulation in horses with and without PPID in winter and autumn.AnimalsTwenty adult horses; 6 controls and 6 with PPID tested in autumn, 8 controls and 6 with PPID tested in winter with 3 controls and 3 with PPID tested in both seasons.MethodsThyrotropin‐releasing hormone stimulation was performed on 2 consecutive occasions, 1 week before and 1 week after the winter solstice and the autumn equinox. Blood was collected before and 30 minutes after IV injection of 1 mg of TRH. ACTH concentration was determined by a chemiluminescent assay. Repeatability and test‐retest reliability were assessed by repeated measures analysis of variance, intraclass correlation coefficient and within‐horse coefficients of variation (CV). Bland‐Altman plots were generated to visualize agreement between repetitions.ResultsIn winter, no week effect was detected on the results of the TRH simulation and the test had an excellent test‐retest reliability. In autumn, after‐TRH ACTH concentrations were significantly lower on week 2 (P = .02) and the test only had a good test‐retest reliability. There were significantly larger within‐horse CV during autumn (P = .04) and after TRH stimulation (P = .04). There were 2 misclassifications in winter and 4 in autumn.Conclusions and Clinical ImportanceThe TRH stimulation test was repeatable when performed 2 weeks apart in winter; however, in autumn, more variability in after‐TRH ACTH concentrations resulted in decreased repeatability.

Impact of blue light therapy on plasma adrenocorticotropic hormone (ACTH) and hypertrichosis in horses with pituitary pars intermedia dysfunction

Blue light therapy can be used in horses to alter the natural photoperiod and inhibit winter hair coat growth. Seasonal increases in ACTH occur in the fall season but are exaggerated in horses with pituitary pars intermedia dysfunction (PPID). Additionally, PPID horses frequently present with hypertrichosis. Thus, blue light therapy was proposed as a potential management tool for hypertrichosis and for investigating the impact of photoperiod manipulation on ACTH. Eighteen PPID horses, aged 18 to 31 yr, from a university-owned research herd were selected and assigned to either the control group (n = 10) or the treatment (blue light therapy) group (n = 8) based on age and clinical history, which included the results of multiple endocrine tests. Consistent daylength of approximately 14.5 h was maintained for the treated horses from July 15 through approximately late October via the extension of natural daylength using wearable masks that provided short wavelength blue light (465 nm) to 1 eye. The control group was exposed to only the natural photoperiod during this time. All horses were housed on the same farm and remained on pasture for the duration of the study. On Day 0, thyrotropin-releasing hormone (TRH) stimulation tests were performed to confirm PPID status; there were no differences between the 2 groups in resting plasma ACTH or plasma ACTH at 10 min after TRH administration. To determine an effect of treatment on ACTH, blood was collected via jugular venipuncture for measurement of ACTH at sequential timepoints over a 16-h period in mid-October. Hair weights were also assessed throughout the study. No differences in resting plasma ACTH were observed between the 2 groups across the seasonal analysis (July and October) or during the 16-h testing. The PPID horses receiving blue light therapy had lighter hair weights compared to the PPID control horses. These results suggest that blue light therapy does not alter ACTH concentrations but could potentially be used as an additional management tool for hypertrichosis in PPID horses. Manipulation of the photoperiod using blue light therapy did not affect seasonal changes in ACTH in this study.

Screening for Mutations in Isolated Central Hypothyroidism Reveals a Novel Mutation in Insulin Receptor Substrate 4.

BackgroundCentral hypothyroidism (CeH) is a rare condition affecting approximately 1:16 000- 100 000 individuals. Congenital forms can harm normal development if not detected and treated promptly. Clinical and biochemical diagnosis, especially of isolated CeH, can be challenging. Cases are not usually detected in neonatal screening, which, in most countries, is focused on detection of the more prevalent primary hypothyroidism. Until now, five genetic causes for isolated CeH have been identified. Here we aimed to identify the genetic cause in two brothers with impaired growth diagnosed with CeH at the age of 5 years. We further evaluated the candidate gene variants in a large genetic database.MethodsClinical and biochemical characterization together with targeted next-generation sequencing (NGS) was used to identify the genetic cause in a family of two brothers presenting with CeH. Screening of insulin receptor substrate 4 (IRS4) variants was carried out in the FinnGen database.ResultsA novel monoallelic frameshift mutation c.1712_1713insT, p.Gly572Trp fs*32 in the X-linked IRS4 gene was identified by NGS analysis in both affected males and confirmed using Sanger sequencing. Their mother was an unaffected carrier. In addition to the declined growth at presentation, central hypothyroidism and blunted TRH test, no other phenotypic alterations were found. Diagnostic tests included head MRI, thyroid imaging, bone age, and laboratory tests for thyroid autoantibodies, glucose, insulin and glycosylated hemoglobin levels. Examination of the IRS4 locus in FinnGen (R5) database revealed the strongest associations to a rare Finnish haplotype associated with thyroid disorders (p = 1.3e-7) and hypothyroidism (p = 8.3e-7).ConclusionsHere, we identified a novel frameshift mutation in an X-linked IRS4 gene in two brothers with isolated CeH. Furthermore, we demonstrate an association of IRS4 gene locus to a general thyroid disease risk in the FinnGen database. Our findings confirm the role of IRS4 in isolated central hypothyroidism.

TRH Stimulation Testing in Older Individuals with Persistent Subclinical Hypothyroidism: A Randomized, Double-Blind, Cross-Over Study of Levothyroxine and Liothyronine Administration

Abstract Background: Subclinical hypothyroidism is common in older individuals. To better understand the underlying physiology, we examined the pituitary-thyroid axis using thyrotropin releasing hormone (TRH) stimulation testing both at baseline and after levothyroxine (LT4) and liothyronine (LT3) supplementation. Methods: We conducted a randomized, double-blind, cross-over study in men and women aged 70 years and over without anti-thyroid peroxidase antibodies with persistent subclinical hypothyroidism, defined as having a TSH level between 4.5 and 19.9 µIU/mL with a normal free thyroxine (FT4) level at two consecutive time points. The primary outcome measures were TSH serum concentration area under the curve (AUC), maximum TSH serum concentration (Cmax), and change in free thyroxine (∆FT4) and total triiodothyronine (∆TT3) levels following TRH stimulation, each measured at three time points: once at baseline and once each after achieving euthyroid TSH levels with the two thyroid preparations. The maximal change in TSH (∆TSH); FT4 and TT3 AUCs; and time to maximal TSH, FT4, and TT3 (Tmax) were also analyzed. Results: Thirteen participants [mean (SD) age 77 (5) years], 4 women and 9 men, completed TRH stimulation testing at baseline and after achieving a TSH level of 0.5-1.5 µIU/mL with each therapy. Baseline mean TSH was 4.84 (1.29) µIU/mL. The mean LT4 dose was 105 (36) µg/day and LT4 dose was 34 (9) µg/day. After TRH stimulation, the mean TSH AUC (0-180) at baseline was 3099.5 (1424.4) µIU*min/mL, and significantly decreased after both LT4 [631.4 (315.2), p&amp;lt;0.001] and LT3 [631.5 (317.3), p&amp;lt;0.001]. There was no difference in TSH AUC (0-180) between LT4 and LT3 treatment arms. Baseline mean TSH Cmax was 27.2 (14.5) µIU/mL and significantly decreased after LT4 [5.5 (3.0), p&amp;lt;0.001] and LT3 [5.4 (2.9), p&amp;lt;0.001], with no difference between the LT4 and LT3 treatment arms. The ∆FT4 was 0.11 (0.07) ng/dL at baseline and decreased significantly on LT3. The ∆TT3 was 0.32 (0.09) ng/mL at baseline and significantly decreased on both LT4 and LT3, with no difference between treatment arms. Conclusions: Older individuals with antibody-negative persistent subclinical hypothyroidism have a heterogeneous TSH response to TRH stimulation. Our data show a significantly diminished response to TRH stimulation after thyroid hormone replacement, and they support the pharmacodynamic equivalence of LT4 and LT3 treatment.

Diagnostic Process in a Crioulo Horse with Cushing’s Syndrome

Background: Equine pituitary pars intermedia dysfunction, also known as equine Cushing’s syndrome, is a neurodegenerative disease. An important risk factor for Cushing’s is advanced aging and it is the most common endocrine disorder in older horses. The prevalence in horses aged over 10 and 15 years is reported as 9.3% and 21%, respectively. Due to the slow progressive nature of the disease, seasonal variation in hormone output and overlapping endocrine response to other events, accurate diagnosis is challenging. The diagnosis requires the combination of anamnesis, clinical signs, in addition to laboratory tests results. This study aimed to report Cushing’s syndrome in a Crioulo breed horse focusing on diagnostic methods.Case: A 13-year-old male Crioulo breed, orchiectomized, was attended at the Universidade de Passo Fundo (UPF), in Passo Fundo, RS, Brazil. The owner reported that the animal had progressive weight loss and coat abnormal growth, with curly appearance. From visual inspection, body condition score was 4 (1-9) bulging abdomen was noticed, hirsutism, depression and lethargy. Also, there was a large neoplastic mass on the left side of gluteal region. Later, this mass was classified in histopathological examination as a fibroblastic sarcoid and was treated. The animal presented physical parameters within the physiological limits of the specie. Normochromic normocytic anemia and neutrophilic leukocytosis were reported in the hematologic evaluation. In coproparasitological examination, there were 300 eggs per gram of feaces. Hyperadrenocorticism was suspected in the clinical examination and dexamethasone suppression test was performed to confirm the fact. Basal serum was collected at 17 h (M0) and subsequently 40 µg/kg of dexamethasone was administered intramuscularly. Serum samples were taken after 15 (M15) and 19 (M19) h, resulting in cortisol levels of 1.7 and 1.8 μg/dL, respectively. The M15 and M19 results were above reference values for horses (below 1 μg/dL). Combination of information gathered from anamnesis, clinical examination and dexamethasone suppression test resulted in the definitive diagnosis of hyperadrenocorticism, also known as Cushing’s syndrome. Paliative treatment included shearing all over the body and vitamin supplementation.Discussion: In animals without obvious clinical signs, Cushing's syndrome diagnosis is challenging. The most unique and specific clinical signs are the development of abnormal hair coat, mainly hirsutism, delayed or incomplete shedding, and in aged horse, lightening of coat color. The mechanistic cause of these signs is still barely understood. Cushing's is a collection of syndromes each with a unique set of clinical signs and hormone profiles, which varies according to each individual. Complementary examinations are extremely important and endocrine tests are highly recommended in addition to suggestive findings. However, despite the variety of existing tests, false negatives or false positives can frequently happen. Dexamethasone suppression test is considered the gold standard, well validated, practical and low cost for the diagnosis of this disease. In the present report, the combination of anamnesis (13 years old, weight loss, and abnormal coat), clinical exam (hirsutism) and dexamethasone suppression test (over 1 μg/dL of cortisol 15 h and 19 h after dexamethasone administration) resulted in the definitive diagnosis of Cushing’s syndrome. Measurements of plasma concentrations of cortisol and adrenocorticotropic hormone (ACTH), thyrotropin releasing hormone (TRH) stimulation test, serum insulin concentration and necropsy are other available tests. History, clinical signs and test results are important to achieve the definitive diagnoses, and when possible, it is advisable to perform post-mortem evaluation of the pituitary gland.

Clinical implications of using adrenocorticotropic hormone diagnostic cutoffs or reference intervals to diagnose pituitary pars intermedia dysfunction in mature horses.

BackgroundDiagnosis of pituitary pars intermedia dysfunction (PPID) is problematic because of large variations in ACTH concentrations.Hypothesis/ObjectivesCompare the test characteristics of baseline and post–thyrotropin‐releasing hormone (TRH) stimulation plasma ACTH concentrations in horses using diagnostic cutoff values (DCOVs) and reference intervals (RIs) and determine the clinical consequences of using each method.AnimalsOne hundred six mature horses: 72 control cases and 34 PPID cases.MethodsProspective case‐controlled study. Horses underwent monthly TRH stimulation tests. Diagnostic cutoff values were determined monthly by receiver operating characteristic curves using the Youden index. Reference intervals were determined monthly by a robust method. For each case age, sex and body condition score (BCS) were recorded.ResultsBaseline ACTH concentrations varied by month (P < .001) with significant “month × age” (P = .003), “month × sex” (P = .003), and “month × BCS” (P = .007) effects. Baseline ACTH concentrations were accurate to diagnose PPID (0.91 ± 0.06) with DCOVs increasing the test sensitivity (0.61 ± 0.21 to 0.87 ± 0.05, P = .002) and RI increasing test specificity (0.85 ± 0.12 to 0.98 ± 0.01, P = .01). Thyrotropin‐releasing hormone stimulation improved test accuracy (0.91 ± 0.06 to 0.97 ± 0.03, P = .004).Conclusions and Clinical ImportanceACTH concentrations follow a circannual rhythm and vary with physiological factors. As using DCOVs increases the ability to detect mild cases and using RI decreases the risk of unnecessary treatments, ACTH concentrations should be interpreted within a specific clinical context. The TRH stimulation test improves the diagnosis of PPID.

Effect of growth hormone therapy on thyroid function in isolated growth hormone deficient and short small for gestational age children: a two-year study, including on assessment of the usefulness of the thyrotropin-releasing hormone (TRH) stimulation test.

Background The relationship between growth hormone (GH)-replacement therapy and the thyroid axis in GH-deficient (GHD) children remains controversial. Furthermore, there have been few reports regarding non-GHD children. We aimed to determine the effect of GH therapy on thyroid function in GHD and non-GHD children and to assess whether thyrotropin-releasing hormone (TRH) stimulation test is helpful for the identification of central hypothyroidism before GH therapy. Methods We retrospectively analyzed data from patients that started GH therapy between 2005 and 2015. The free thyroxine (FT4) and thyroid-stimulating hormone (TSH) concentrations were measured before and during 24months of GH therapy. The participants were 149 children appropriate for gestational age with GHD (IGHD: isolated GHD) (group 1), 29 small for gestational age (SGA) children with GHD (group 2), and 25 short SGA children (group 3). Results In groups 1 and 2, but not in group 3, serum FT4 concentration transiently decreased. Two IGHD participants exhibited central hypothyroidism during GH therapy, and required levothyroxine (LT4) replacement. They showed either delayed and/or prolonged responses to TRH stimulation tests before start of GH therapy. Conclusions GH therapy had little pharmacological effect on thyroid function, similar changes in serum FT4 concentrations were not observed in participants with SGA but not GHD cases who were administered GH at apharmacological dose. However, two IGHD participants showed central hypothyroidism and needed LT4replacement therapy during GH therapy. TRH stimulation test before GH therapy could identify such patients and provoke careful follow-up evaluation of serum FT4 and TSH concentrations.

A remarkable case of thyrotoxicosis initially caused by graves\u2019 disease followed by a probable TSHoma \u2013 a case report

BackgroundGraves’ disease is the commonest cause of thyrotoxicosis whilst thyrotropin (TSH)-producing pituitary adenomas (thyrotropinomas, TSHomas) are very rare and account for just 1–2% of all pituitary adenomas. Coexistence of a TSHoma and Graves’ disease has been very rarely reported. Here, we report a case of a patient whose initial presentation with primary thyrotoxicosis due to Graves’ disease, was subsequently followed by a relapse of thyrotoxicosis due to a probable TSHoma.CaseA sixty-eight year old woman was referred to our department with classical features of thyrotoxicosis. Initial biochemistry confirmed hyperthyroxinaemia [free thyroxine (fT4) 20.4 pmol/L (reference range 7.0–16.0)] and a suppressed TSH [< 0.02mIU/L (0.50–4.20)]. A technetium pertechnetate uptake scan was consistent with Graves’ Disease. She was treated with carbimazole for 18 months and remained clinically and biochemically euthyroid. After stopping carbimazole her fT4 started to rise but TSH remained normal. Laboratory assay interference was excluded. A TRH stimulation test demonstrated a flat TSH response and pituitary MRI revealed a microadenoma. Remaining pituitary hormones were in the normal range other than a slightly raised IGF-1. An 11C-methionine PET/CT scan coregistered with volumetric MRI (Met-PET-MRICR) demonstrated high tracer uptake in the left lateral sella region suggestive of a functioning adenoma. The patient declined surgery and was unable to tolerate cabergoline or octreotide. Thereafter, she has elected to pursue a conservative approach with periodic surveillance.ConclusionThis is a very unusual case of thyrotoxicosis caused by two different processes occurring in the same patient. It highlights the importance of considering dual pathology when previously concordant thyroid function tests become discordant. It also highlights a potential role of Met-PET-MRICR in the localisation of functioning pituitary tumours.

Growth hormone and periarticular new bone formation--a causal relationship? A preliminary communication

In an attempt to examine the relationship between growth hormone (GH) and periarticular new bone formation (PNBF), we studied eight patients with brain lesions of different origins who were in a prolonged comatose state for 164 to 1320 days. Five of them developed PNBF. The latter reacted to both the specific L-Dopa test and to the non-specific TRH test with an increase in GH serum concentration. Those patients who did not develop PNBF, failed to react significantly to either tests. The difference in GH values between the two groups is statistically significant at the 95% level of confidence. We hypothesize that there may be a causal relationship between high concentrations of GH in serum and PNBF.

Can Endocrine Dysfunction Be Reliably Tested in Aged Horses That Are Experiencing Pain?

Simple SummaryPituitary pars intermedia dysfunction (PPID) is an endocrine (secreting internally) disease of aged horses and ponies. An enlargement (hyperplasia) of the pars intermedia of the pituitary gland leads to an increased secretion of hormones, including adrenocorticotropic hormone (ACTH). The main tests for a diagnosis of PPID are the measurement of basal ACTH and the thyrotropin-releasing hormone (TRH) stimulation test, where TRH stimulates the secretion of ACTH. Since pain can also lead to elevated concentrations of ACTH, it is unclear whether horses with pain can be tested for PPID correctly. The aim of the present study was to find out whether pain caused a marked increase of ACTH can lead to a false positive result in the diagnosis of PPID. Therefore, we examined fifteen horses treated for different pain conditions, which also served as their own controls as soon as they were pain-free again. The ACTH and cortisol were measured before and after the TRH stimulation test. There was no significant difference in the ACTH concentration in horses with pain and the controls, between different pain intensities or between disease groups. Thus, measuring the basal ACTH concentration and performing the TRH stimulation test for the diagnosis of PPID seem to be possible in horses with a treated low to moderate pain condition.The aim of the present study was to evaluate (i) the effects of different intensities and types of treated pain on the basal concentrations of adrenocorticotropic hormone (ACTH) and cortisol, and (ii) the thyrotropin-releasing hormone (TRH) stimulation test, to determine whether treated pain caused a marked increase of ACTH, which would lead to a false positive result in the diagnosis of pituitary pars intermedia dysfunction (PPID). Methods: Fifteen horses with treated low to moderate pain intensities were part of the study. They served as their own controls as soon as they were pain-free again. The horses were divided into three disease groups, depending on their underlying disease (disease group 1 = colic, disease group 2 = laminitis, disease group 3 = orthopedic problems). A composite pain scale was used to evaluate the intensity of the pain. This pain scale contained a general part and specific criteria for every disease. Subsequently, ACTH and cortisol were measured before and after the intravenous application of 1 mg of TRH. Results: There was no significant difference in the basal or stimulated ACTH concentration in horses with pain and controls, between different pain intensities or between disease groups. Descriptive statistics, however, revealed that pain might decrease the effect of TRH on the secretion of ACTH. There was an increase of ACTH 30 min after TRH application (p = 0.007) in the treated pain group, but this difference could not be statistically confirmed. Measuring the basal ACTH concentration and performing the TRH stimulation test for the diagnosis of PPID seem to be possible in horses with low to moderate pain.

Effects of pituitary pars intermedia dysfunction and Prascend (pergolide tablets) treatment on endocrine and immune function in horses

It remains unclear how pituitary pars intermedia dysfunction (PPID) and pergolide treatment (Prascend [pergolide tablets]) affect endocrine and immune function in horses. To evaluate these effects, blood was collected regularly from 28 university-owned horses (10 Non-PPID, 9 PPID control [PC], and 9 PPID treatment [PT]) over approximately 15 mo. Pergolide treatment was initiated after Day 0 collections. Analyses included ACTH, insulin, total cortisol, free cortisol, complete blood counts, plasma myeloperoxidase, and cytokine/receptor gene expression in basal whole blood and in vitro stimulations (PMA/ionomycin, heat-inactivated Rhodococcus equi, and heat-inactivated Escherichia coli) of whole blood and peripheral blood mononuclear cells (PBMCs). The results were analyzed using a linear mixed model (SAS 9.4) with significance set at P < 0.05. Significant group (P = 0.0014) and group-by-time (P = 0.0004) effects were observed in resting ACTH such that PT horses differed from Non-PPID horses only at Day 0. PT horses had significantly lower changes in ACTH responses to thyrotropin-releasing hormone stimulation tests than PC horses at non-fall time points only, mid-late February 2018 (P = 0.016) and early April 2018 (P = 0.0172). When PT and PC horses did not differ, they were combined before comparison to Non-PPID horses. No significant group or group-by-time effects were seen in resting insulin, total cortisol, or free cortisol; however, significant time effects were observed in these measures. PPID horses had lower absolute lymphocyte (P = 0.028) and red blood cell (P = 0.0203) counts than Non-PPID horses. In unstimulated whole blood, PPID horses had increased IL-8 expression compared with Non-PPID horses (P = 0.0102). In addition, PPID horses had decreased interferon γ production from PBMCs after stimulation with R. equi (P = 0.0063) and E. coli (P = 0.0057) and showed increased transforming growth factor β expression after E. coli stimulation (P = 0.0399). The main limitations of this study were a limited sample size and an inability to truly randomize the PPID horses into treatment groups. Resting ACTH is likely the best choice for determining successful responses to pergolide. Neither PPID nor pergolide appears to influence insulin, total cortisol, and free cortisol. As measured, systemic immune function was altered in PPID horses, and it is likely that these horses are indeed at increased risk of opportunistic infection. Despite reducing ACTH, pergolide treatment did not appear to influence immune function.

Antenatal corticosteroids for threatened labour facilitate thyroid maturation among preterm neonates.

To examine the effect of antenatal corticosteroids (ANS) on the maturation of thyroid function in the preterm infants. ANS reduce mortality and morbidities in preterm neonates. Organ maturation by the glucocorticoids is the key, at least in part. However, the effect of ANS on thyroid is controversial. A study group of 99 very low birthweight neonates (<34weeks' gestational age) with the exception of those born more than 7days after ANS administration were divided into a complete group (n=49) whose mothers completed two doses of betamethasone and who were born more than 24hours after the completion of ANS administration, and an incomplete group (n=50) who were not exposed to any ANS or were born within 24hours after the completion of ANS administration. Serum-free thyroxine and thyroid-stimulating hormone (TSH) levels were measured, and thyrotropin-releasing hormone (TRH) stimulation tests were performed at about 2weeks of age. The incidence of hyperthyrotropinaemia (TSH>15 mIU/L) in the complete group was significantly lower than in the incomplete group (6% vs 22%, P=.023). Exaggerated responses to TRH tests were more frequent in the incomplete group (17% vs 44%; P=.053). TSH30 was significantly lower in the complete group, (P=.046). Multivariate logistic regression analysis showed that the incidence of hyperthyrotropinaemia was associated with complete ANS administration (adjusted odds ratios 0.39). ANS administration might facilitate thyroid maturation in preterm neonates.

The Differential Diagnosis of Discrepant Thyroid Function Tests: Insistent Pitfalls and Updated Flow-Chart Based on a Long-Standing Experience.

Background: Discrepant thyroid function tests (TFTs) are typical of inappropriate secretion of TSH (IST), a rare entity encompassing TSH-secreting adenomas (TSHoma) and Resistance to Thyroid Hormone (RTHβ) due to THRB mutations. The differential diagnosis remains a clinical challenge in most of the cases. The objective of this study was to share our experience with patients presenting with discrepant TFTs outlining the main pitfalls in the differential diagnosis.Methods: medical records of 100 subjects with discrepant TFTs referred to Thyroid Endocrine Centers at the University of Milan were analyzed, retrospectively. Patients were studied by dynamic testing (TRH test, T3-suppression test, or a short course of long-acting somatostatin analog, when appropriate), THRB sequencing, and pituitary imaging.Results: 88 patients were correctly diagnosed as RTHβ with (n = 59; 16 men, 43 women) or without THRB variants (n = 6; 2 men, 4 female) or TSHoma (n = 23; 9 men, 14 women). We identified 14 representative subjects with an atypical presentation or who were misdiagnosed. Seven patients, with spurious hyperthyroxinemia due to assays interference were erroneously classified as RTHβ (n = 4) or TSHoma (n = 3). Three patients with genuine TSHomas were classified as laboratory artifact (n = 2) or RTHβ (n = 1). Two TSHomas presented atypically due to coexistent primary thyroid diseases. In one RTHβ a drug-induced thyroid dysfunction was primarily assumed. These patients experienced a mean diagnostic delay of 26 ± 14 months. Analysis of the investigations which can differentiate between TSHoma and RTHβ showed highest accuracy for the T3-suppression test (100% specificity with a cut-off of TSH <0.11 μUI/ml). Pituitary MRI was negative in 6/26 TSHomas, while 11/45 RTHβ patients had small pituitary lesions, leading to unnecessary surgery in one case.Conclusions: Diagnostic delay and inappropriate treatments still occur in too many cases with discrepant TFTs suggestive of central hyperthyroidism. The insistent pitfalls lead to a significant waste of resources. We propose a revised flow-chart for the differential diagnosis.