Prevalence and predictors of hyperprolactinemia in subclinical hypothyroidism

Systematic review of the association between thyroid disorders and hyperprolactinemia

INTRODUCTION

Thyroid disease (TD), particularly hypothyroidism, is an important etiology of hyperprolactinemia (HPRL). We conducted a systematic review of the clinical characteristics, management, and outcomes of adults (> 18 years) with this clinical association.

MATERIALS AND METHODS

We searched PUBMED, SCOPUS, and EMBASE to find eligible articles published in English from any date till 15th December 2022.

RESULTS

The final systematic review included 804 patients from 47 articles, of which the majority (85.9%) were females. Menstrual irregularity was the most prominent symptom of HPRL (74.3%). Subclinical hypothyroidism (57.1%) was the most reported TD. Individual patient data were available for 62 patients from 35 studies. The median age was 32 (25-42) years, TSH was 110.25 (50-345.4) mU/L, and PRL level was 60 (37.6-91) ng/ml. On treating TD, 38 (70.4%) patients had complete resolution and 10 (18.5%) had an improvement in HPRL. Of 38 patients with pituitary imaging, 26 (68.4%) showed pituitary enlargement, and 13 (34.2%) showed a suprasellar extension. 13 (76.5%) patients had complete resolution and 3 (17.6%) had an improvement in pituitary enlargement on TD treatment. A positive correlation was observed between higher serum TSH levels and higher serum prolactin levels. Patients with pituitary enlargement on imaging had a higher TSH level compared to those without any pituitary enlargement (Median of 263 (61-602) vs. 50 (24.3-128) mU/L; p-value = 0.01).

CONCLUSION

Thyroid hormone replacement can lead to resolution of HPRL and pituitary enlargement in the majority of patients with HPRL due to overt or subclinical hypothyroidism without the need for dopamine agonist treatment.

Overview of Hyperprolactinemia: General Approach and Reproductive Health Implications

Prolactin (PRL) is a polypeptide hormone produced by the lactotrope cells of the anterior pituitary gland. Among its myriads of biological functions, PRL is the main regulator of mammary gland growth and development, as well as of the production and secretion of milk. Hyperprolactinemia represents a frequent consultation cause in medical practice. Nevertheless, elevations in serum PRL are not always pathological. Drug induced hyperprolactinemia is the most common cause, mainly by antipsychotics, followed by other causes such as pituitary neuroendocrine tumors, physiologic conditions, and systemic diseases such as chronic kidney disease and hypothyroidism. When evaluating a patient with hyperprolactinemia it is of utmost importance to consider the diverse etiologies of this condition in order to avoid unnecessary diagnostic workup and treatment. Regarding reproductive health, hyperprolactinemia is a well-documented cause of infertility, as approximately 15-20% of women undergoing infertility evaluation have hyperprolactinemia, which causes secondary amenorrhea, and other menstrual irregularities. Similarly, in men it is a cause of hypogonadism.

The beneficial and detrimental effects of prolactin hormone on metabolic syndrome: A double-edge sword

The metabolic syndrome (MetS) is a clustering of abdominal obesity, hypertension, hyperglycaemia, hypertriglyceridemia and low high-density lipoprotein (HDL) level. MetS development is affected by endocrine hormones such as prolactin (PRL) hormone which induce insulin resistance and central obesity because PRL is implicated in the pathogenesis of MetS. Pituitary PRL controls mammary gland, however extra-pituitary PRL is highly intricate in the regulation of adipose tissue function. In addition, cAMP activators enhance expression and release of PRL which involved in the control of lipogenesis and energy homeostasis. Consequently, hyperprolactinaemia may be associated with the development of MetS. However, normal physiological level of PRL is essential for insulin sensitivity and regulation of adipose tissue function and energy metabolism. Therefore, PRL has dual effects on the components of MetS. Hence, the present review aims to discuss the modulatory mechanistic role of PRL on MetS regarding its beneficial and detrimental effects.

The research trend of hyperprolactinemia from 2011 to 2023 was analyzed by bibliometrics

The objective of this study is to conduct a bibliometric analysis of research trends in hyperprolactinemia from 2011 to 2023. This analysis aims to provide researchers with insights into the current hotspots and frontiers related to hyperprolactinemia. It is worth noting that there are currently no existing reports on bibliometric analyses of hyperprolactinemia. The Social Science Citation Index (SSCI) and Science Citation Index Expanded (SCIE) databases of the Web of Science Core Collection were systematically searched for "articles" and "review articles" related to the topic of hyperprolactinemia from 2011 to 2023. VOSviewer was employed to conduct bibliometric analysis, aiming to analyze the research trends in hyperprolactinemia over the past 13 years. A total of 1865 eligible articles were retrieved, with contributions from 9544 scholars representing 83 countries in the field of research. The United States had the highest number of publications, followed by China. The keywords were categorized into six clusters: (1) etiology of hyperprolactinemia and other related endocrine and metabolic diseases. (2) Hyperprolactinemia and mental illness. (3) Diagnosis and management of hyperprolactinemia. (4) Treatment of hyperprolactinemia and prolactinoma. (5) Detection of macroprolactin and macroprolactinemia. (6) Symptoms of male hyperprolactinemia. Over the past 13 years, there has been a consistent and slightly increasing trend in the number of research papers focusing on hyperprolactinemia. The primary areas of research focus are centered around the diagnosis and treatment of hyperprolactinemia caused by antipsychotic drugs or prolactinoma.

Pituitary Hyperplasia Due to Longstanding Primary Hypothyroidism: A Case Report and Comprehensive Review of the Literature

Hypothyroidism is a frequently diagnosed endocrine disorder. Common signs and symptoms include fatigue, cold intolerance, hoarseness, dry skin, constipation, a slow relaxation phase of deep tendon reflexes, and bradycardia. However, some patients may exhibit atypical signs and symptoms, which can result in diagnostic confusion. Pituitary hyperplasia resulting from longstanding primary hypothyroidism was first described by Niepce in 1851. It is usually asymptomatic, but sometimes, in addition to symptoms of overt hypothyroidism, patients may complain of headaches, hypopituitarism, visual field impairment, and hyperprolactinemia. Furthermore, on imaging, pituitary hyperplasia can be mistaken for a pituitary adenoma. Distinguishing between the two is crucial, as their management differs; the former often responds to thyroid hormone replacement therapy, while the latter might need treatment with surgery and/or radiotherapy. Here we describe a patient who developed pituitary hyperplasia in the setting of longstanding uncompensated primary hypothyroidism due to a lack of compliance with levothyroxine replacement therapy. We also review the clinical, laboratory, and radiologic findings of the case reports available in the literature up to now in order to improve the knowledge and the care of the disease.

Consensus guideline for the diagnosis and management of pituitary adenomas in childhood and adolescence: Part 2, specific diseases

Pituitary adenomas are rare in children and young people under the age of 19 (hereafter referred to as CYP) but they pose some different diagnostic and management challenges in this age group than in adults. These rare neoplasms can disrupt maturational, visual, intellectual and developmental processes and, in CYP, they tend to have more occult presentation, aggressive behaviour and are more likely to have a genetic basis than in adults. Through standardized AGREE II methodology, literature review and Delphi consensus, a multidisciplinary expert group developed 74 pragmatic management recommendations aimed at optimizing care for CYP in the first-ever comprehensive consensus guideline to cover the care of CYP with pituitary adenoma. Part 2 of this consensus guideline details 57 recommendations for paediatric patients with prolactinomas, Cushing disease, growth hormone excess causing gigantism and acromegaly, clinically non-functioning adenomas, and the rare TSHomas. Compared with adult patients with pituitary adenomas, we highlight that, in the CYP group, there is a greater proportion of functioning tumours, including macroprolactinomas, greater likelihood of underlying genetic disease, more corticotrophinomas in boys aged under 10 years than in girls and difficulty of peri-pubertal diagnosis of growth hormone excess. Collaboration with pituitary specialists caring for adult patients, as part of commissioned and centralized multidisciplinary teams, is key for optimizing management, transition and lifelong care and facilitates the collection of health-related quality of survival outcomes of novel medical, surgical and radiotherapeutic treatments, which are currently largely missing.

Hyperprolactinemia Due to Prolactinoma has an Adverse Impact on Bone Health with Predominant Impact on Trabecular Bone: A Systematic Review and Meta-Analysis

BACKGROUND

No meta-analysis has holistically analysed and summarized the effect of prolactin excess due to prolactinomas on bone mineral metabolism. We undertook this meta-analysis to address this knowledge-gap.

METHODS

Electronic databases were searched for studies having patients with hyperprolactinemia due to prolactinoma and the other being a matched control group. The primary outcome was to evaluate the differences in BMD Z-scores at different sites. The secondary outcomes of this study were to evaluate the alterations in bone mineral density, bone mineral content and the occurrence of fragility fractures.

RESULTS

Data from 4 studies involving 437 individuals was analysed to find out the impact of prolactinoma on bone mineral metabolism. Individuals with prolactinoma had significantly lower Z scores at the lumbar spine [MD -1.08 (95 % CI: -1.57 - -0.59); P < 0.0001; I2 = 54 % (moderate heterogeneity)] but not at the femur neck [MD -1.31 (95 % CI: -3.07 - 0.45); P = 0.15; I2 = 98 % (high heterogeneity)] as compared to controls. Trabecular thickness of the radius [MD -0.01 (95 % CI: -0.02 - -0.00); P = 0.0006], tibia [MD -0.01 (95 % CI: -0.02 - -0.00); P=0.03] and cortical thickness of the radius [MD -0.01 (95 % CI: -0.19 - -0.00); P = 0.04] was significantly lower in patients with prolactinoma as compared to controls. The occurrence of fractures was significantly higher in patients with prolactinoma as compared to controls [OR 3.21 (95 % CI: 1.64 - 6.26); P = 0.0006] Conclusion: Bone mass is adversely affected in patients with hyperprolactinemia due to prolactinoma with predominant effects on the trabecular bone.

The clinicopathological features, treatment outcomes and follow-up results of 47 ectopic thyroid gland cases: a single-center retrospective study

Background

Ectopic thyroid gland (ETG) is an uncommon clinical condition, presenting various challenges and limitations in its regulate diagnosis and treatment currently. This study aims to enhance our understanding of ETG and improve the strategies for its diagnosis and treatment.

Methods

The retrospective single-center study was conducted, encompassing clinical data from ETG patients screened at our institution between 2013 and 2022. Patients were categorized based on the location of the disease, and follow-ups were performed on each.

Results

This study included a total of 47 patients who were confirmed to hav confirmed to have ETG. Among them, we found 29 cases of accessory thyroid and 18 cases of aberrant thyroid. Furthermore, 42 cases exhibited the single ETG, while 5 cases displayed the double ETG. The distribution of the ETG was as follows: 20 were lingual, 10 were submandibular, 10 were lateral cervical, 4 were thoracic mediastinal, 1 was esophageal, and 7 were ovarian. Of these cases, 22 patients underwent surgery, 18 received thyroid hormone replacement therapy, and 7 were placed under observation. All patients were followed up for 59.4 (12-117) months. No significant abnormalities were detected at the conclusion of the follow-up period.

Conclusion

ETG is frequently observed in the head and neck, particularly in lingual. Accessory thyroid glands are commonly reported, with most cases being single ETG. Notably, these glands usually do not manifest specific clinical symptoms. Therefore, the appropriate and comprehensive examinations during the initial diagnosis are crucial to avoid misdiagnosis. Treatment should be individualized, and long-term follow-up is essential for managing ETG effectively.

The Thyroid Hormone Axis and Female Reproduction

Thyroid function affects multiple sites of the female hypothalamic-pituitary gonadal (HPG) axis. Disruption of thyroid function has been linked to reproductive dysfunction in women and is associated with menstrual irregularity, infertility, poor pregnancy outcomes, and gynecological conditions such as premature ovarian insufficiency and polycystic ovarian syndrome. Thus, the complex molecular interplay between hormones involved in thyroid and reproductive functions is further compounded by the association of certain common autoimmune states with disorders of the thyroid and the HPG axes. Furthermore, in prepartum and intrapartum states, even relatively minor disruptions have been shown to adversely impact maternal and fetal outcomes, with some differences of opinion in the management of these conditions. In this review, we provide readers with a foundational understanding of the physiology and pathophysiology of thyroid hormone interactions with the female HPG axis. We also share clinical insights into the management of thyroid dysfunction in reproductive-aged women.

Thyroid hormones in canine pregnancy and lactation

It is believed that thyroid function has a significant effect on fertility and fetal development in mammals. So far, however, only few studies have been published about potential effects of the reproductive cycle stage on thyroid hormone concentrations in dogs. Therefore, over the course of 122 pregnant and non-pregnant cycles in healthy bitches, Thyroid stimulating hormone (TSH), free Thyroxine (fT4), total Thyroxine (tT4) and Progesterone (P4) were measured six times to assess the influence of the cycle stage and pregnancy on hormone concentrations. The aim was to evaluate established reference intervals for the thyroid hormones in a female study population. Of the 122 bitches, 98 became pregnant. Blood samples were collected during estrus, three times in pregnancy, during lactation and after weaning, or at equivalent times during and after estrus in non-pregnant dogs. No differences between pregnant and non-pregnant animals in any of the thyroid hormones were found. Hormone concentrations, however, differed significantly between the six samplings (p < .01). TSH initially declined during pregnancy, then rose again. The mean concentration of all dogs exceeded the overall upper reference limit of 0.70 ng/mL during lactation. Concentrations of tT4 and ft4 increased during the first third of pregnancy and then subsequently declined. The overall reference limits for tT4 were 0.47-3.20 μg/dL, and for fT4 4.86-29.60 pmol/L, but the reference intervals varied between the sampling dates. The observed patterns may reflect that maternal tT4 and fT4 seem to have important effects during early pregnancy, including a pronounced negative feedback effect on TSH. The initial increase and subsequent decline of tT4 and fT4 concentrations during the course of pregnancy is in accordance with findings in humans and may support the development of fetal thyroid function. The observed peak of TSH concentrations during lactation suggests that the demand for thyroid hormones in this phase is largest. Even if the underlying causes and mechanisms of thyroid regulation are not fully understood, the results of this study show relevant changes of hormone concentrations in the course of the sexual cycle and pregnancy. In that regard, cycle stage needs to be considered when assessing thyroid function in bitches.

Hyperprolactinaemia is common in Chinese premenopausal women with breast diseases

Purpose: Hyperprolactinaemia has been proposed to play a role in breast lesions pathophysiology. Thus far, controversial results have been reported for the relationship between hyperprolactinaemia and breast lesions. Moreover, the prevalence of hyperprolactinaemia in a population with breast lesions is scarcely reported. We aimed to investigate the prevalence of hyperprolactinaemia in Chinese premenopausal women with breast diseases, and explore the associations between hyperprolactinaemia with different clinical characteristics. Methods: This was a retrospective cross-sectional study performed in the department of breast surgery of Qilu hospital of Shandong University. Overall, 1,461 female patients who underwent the serum prolactin (PRL) level assay before breast surgery from January 2019 to December 2020 were included. Patients were divided into two groups: before and after menopause. Data were analyzed using SPSS 18.0 software. Results: The results showed an elevated PRL level in 376 of the 1,461 female patients with breast lesions (25.74%). Furthermore, the proportion of hyperprolactinemia among premenopausal patients with breast disease (35.75%, 340/951) was significantly higher than among postmenopausal patients with breast disease (7.06%, 36/510). In premenopausal patients, the proportion of patients with hyperprolactinaemia and the mean serum PRL level were significantly higher in those diagnosed with fibroepithelial tumours (FETs) and in younger patients (aged < 35 years) than in those with non-neoplastic lesions and in those aged ≥ 35 years (both p < 0.05). Especially, the prolactin level exhibited steady ascending tendency for positive correlation with FET. Conclusion: Hyperprolactinaemia is prevalent in Chinese premenopausal patients with breast diseases, especially in those with FETs, which implies a potential association, to some extent, between the PRL levels in various breast diseases.

Genetically predicted alterations in thyroid function are associated with the risk of benign prostatic disease

Background

Benign prostatic diseases (BPDs), such as benign prostate hyperplasia (BPH) and prostatitis, harm the quality of life of affected patients. However, observational studies exploring the association between thyroid function and BPDs have hitherto yielded inconsistent results. In this study, we explored whether there is a causal genetic association between them using Mendelian randomization (MR) analysis.

Methods

We used publicly available summary statistics from the Thyroidomics Consortium and 23andMe on thyrotropin (TSH; 54,288 participants), thyroxine [free tetraiodothyronine (FT4); 49,269 participants], subclinical hypothyroidism (3,440 cases and 49,983 controls), overt hypothyroidism (8,000 cases and 117,000 controls), and subclinical hyperthyroidism (1,840 cases and 49,983 controls) to screen for instrumental variables of thyroid function. Results for BPD such as prostatic hyperplasia (13,118 cases and 72,799 controls) and prostatitis (1,859 cases and 72,799 controls) were obtained from the FinnGen study. The causal relationship between thyroid function and BPD was primarily assessed using MR with an inverse variance weighted approach. In addition, sensitivity analyses were performed to test the robustness of the results.

Results

We found that TSH [OR (95% CI) = 0.912(0.845-0.984), p =1.8 x 10^-2], subclinical hypothyroidism [OR (95% CI) = 0.864(0.810-0.922), p =1.04 x 10^-5], and overt hypothyroidism [OR (95% CI) = 0.885 (0.831-0. 944), p =2 x 10^-4] had a significant effect on genetic susceptibility to BPH, unlike hyperthyroidism [OR (95% CI) = 1.049(0.990-1.111), p =1.05 x 10^-1] and FT4 [OR (95% CI) = 0.979(0.857-1.119), p = 7.59 x 10^-1] had no effect. We also found that TSH [OR (95% CI) =0.823(0.700-0.967), p = 1.8 x 10^-2] and overt hypothyroidism [OR (95% CI) = 0.853(0.730-0.997), p = 4.6 x 10^-2] significantly influenced the prostatitis, whereas FT4 levels [OR (95% CI) = 1.141(0.901-1.444), p = 2.75 x 10^-1], subclinical hypothyroidism [OR (95% CI) =0. 897(0.784- 1.026), p = 1.12 x 10^-1], and hyperthyroidism [OR (95% CI) = 1.069(0.947-1.206), p = 2.79 x 10^-1] did not have a significant effect.

Conclusion

Overall, our study results suggest that hypothyroidism and TSH levels influence the risk of genetically predicted BPH and prostatitis, providing new insights into the causal relationship between thyroid function and BPD.

Increase in Thyrotropin Is Associated with an Increase in Serum Prolactin in Euthyroid Subjects and Patients with Subclinical Hypothyroidism

Background: Prevalence and clinical significance of hyperprolactinemia in subclinical hypothyroidism have been reported in few studies. The upper limit of the normal range for TSH used to diagnose subclinical hypothyroidism is a matter of controversy. Some experts believe that the upper limit of the normal TSH range should be reduced from 4.2 to 2.5 mIU/L. Some evidence suggests a positive relationship between TSH > 2.5 mIU/L and cortisol as an indicator of metabolic stress. With this view prolactin as a stress hormone can be elevated in TSH >2.5 in comparison to TSH< 2.5. Hence the aim of this study was to evaluate the relationship between TSH and prolactin levels in the TSH range <10.

Methods: This cross-sectional study was performed on apparently healthy subjects with TSH<10 mIU/L. Subjects with the age of 18 to 35 years were enrolled. The sera were analyzed for prolactin, FT3, FT4, TSH, TPO-Ab and Tg-Ab.

Results: From the total number of 519 participants, in 65 subjects (12.5%) TSH was < 2.5. Seventy-nine subjects (15.2%) had TSH: 2.5-4.2 and 375 (72.3%) of the participants had TSH> 4.2 mIU/L. The mean age, weight and BMI of subjects in the three TSH groups were not significantly different. In the three TSH groups, the prevalence of hyperprolactinemia was zero, 3.8 and 30.7%, respectively. There was a positive and significant correlation between prolactin and TSH levels (r=0.613).

Conclusion: Hyperprolactinemia is common in patients with subclinical hypothyroidism (30.7%) and there is a positive correlation between TSH and PRL in subjects with TSH<10 mIU/l.

Metoclopramide Test in Hyperprolactinemic Women With Polycystic Ovarian Syndrome: Old Wine Into New Bottles?

INTRODUCTION

Polycystic ovarian syndrome (PCOS) is the most frequent etiology of anovulation, hyperandrogenism and infertility in women. Its pathophysiology remains poorly elucidated. Hyperprolactinemia (hPRL) is common in women of reproductive age and may partially mimic the clinical phenotype of PCOS. The simultaneous finding of both conditions is therefore not rare, however there are conflicting studies on whether a link exists between them.

MATERIALS AND METHODS

We conducted a retrospective monocentric study between 2015 and 2021 and among women who were referred for possible PCOS, we selected those who met the ESHRE/Rotterdam definition criteria. hPRL was defined as two values above the upper limit of normal with at least one measurement in our centre.

RESULTS

A total of 430 women were selected, of whom 179 met the PCOS criteria. 50 out of 179 patients (27.9%) had at least one elevated value of PRL and 21 (11.7%) had hPRL according to our definition. Among the 21 women of the PCOS/hPRL cohort, 5 (23.8%) had a microprolactinoma and all of them had PRL level ≥ 60 ng/ml. The remaining cases were macroprolactinemia (n=5), iatrogenic hPRL (n=4), primary hypothyroidism (n=1) or unexplained (n=6) despite exhaustive investigations. The metoclopramide test resulted in an increase of basal PRL < 300% in all prolactinomas and ≥ 300% in all the other etiologies.

CONCLUSION

hPRL was a common finding in PCOS women, secondary to a microprolactinoma in a quarter of cases. Metoclopramide test performed in women with hPRL below 60 ng/ml appeared as a helpful tool 1) to discriminate pituitary causes from others etiologies, 2) to potentially avoid unnecessary pituitary MRI.

Prevalence of Macroprolactinemia in People Detected to Have Hyperprolactinemia

Background Macroprolactinemia is an analytic laboma encountered as a part of prolactin assay. No data are available on the burden of macroprolactinemia in Indians. This study aimed to determine the prevalence and predictors of macroprolactinemia among people with hyperprolactinemia.

Methods Consecutive patients detected to have serum prolactin > 18 ng/mL as per the upper reference limit were further screened for macroprolactin by post-polyethylene-glycol (PEG)-precipitation test. Macroprolactinemia was defined as post-PEG recovery of prolactin < 40%.

Results The four most common underlying etiologies for the testing of hyperprolactinemia were polycystic ovary syndrome ( n = 402; 32.71%), pituitary adenomas ( n = 318; 25.87%), drug-induced hyperprolactinemia ( n = 224; 18.23%), and infertility ( n = 126; 10.25%). A total of 1,229 patients (male:female = 191:1038) having mean age 30.46 ± 10.14 years had hyperprolactinemia, of which 168 (13.7%) were diagnosed to have macroprolactinemia. Macroprolactinemia was significantly higher in females than males (15.03 vs. 6.28%; p < 0.001). Age quartile-based analysis revealed no difference in occurrence of macroprolactinemia. Only 34 patients (2.76%) with macroprolactinemia (< 40% recovery of prolactin post-PEG precipitation) had raised prolactin levels after recovery. These patients primarily had underlying pituitary pathology.

Conclusion Macroprolactinemia is not uncommon in people being tested for hyperprolactinemia. We should not hesitate to screen for macroprolactinemia in patients who have incidentally been detected to have hyperprolactinemia.

Metabolic effects of prolactin and the role of dopamine agonists: A review

Prolactin is a polypeptide hormone that is well known for its role in reproductive physiology. Recent studies highlight its role in neurohormonal appetite regulation and metabolism. Elevated prolactin levels are widely associated with worsening metabolic disease, but it appears that low prolactin levels could also be metabolically unfavorable. This review discusses the pathophysiology of prolactin related metabolic changes, and the less commonly recognized effects of prolactin on adipose tissue, pancreas, liver, and small bowel. Furthermore, the effect of dopamine agonists on the metabolic profiles of patients with hyperprolactinemia are discussed as well.

Relationships Between 24-hour LH and Testosterone Concentrations and With Other Pituitary Hormones in Healthy Older Men

Objective

To investigate the relationship between LH and testosterone (T), which characteristics associate with the strength of this relationship, and their interrelationships with GH, TSH, cortisol, and ACTH.

Design

Hormones were measured in serum samples collected every 10 minutes during 24 hours from 20 healthy men, comprising 10 offspring of long-lived families and 10 control subjects, with a mean (SD) age of 65.6 (5.3) years. We performed cross-correlation analyses to assess the relative strength between 2 timeseries for all possible time shifts.

Results

Mean (95% CI) maximal correlation was 0.21 (0.10-0.31) at lag time of 60 minutes between LH and total T concentrations. Results were comparable for calculated free, bioavailable, or secretion rates of T. Men with strong LH-T cross-correlations had, compared with men with no cross-correlation, lower fat mass (18.5 [14.9-19.7] vs. 22.3 [18.4-29.4] kg), waist circumference (93.6 [5.7] vs. 103.1 [12.0] cm), high-sensitivity C-reactive protein (0.7 [0.4-1.3] vs. 1.8 [0.8-12.3] mg/L), IL-6 (0.8 [0.6-1.0] vs. 1.2 [0.9-3.0] pg/mL), and 24-hour mean LH (4.3 [2.0] vs. 6.1 [1.5] U/L), and stronger LH-T feedforward synchrony (1.5 [0.3] vs. 1.9 [0.2]). Furthermore, T was positively cross-correlated with TSH (0.32 [0.21-0.43]), cortisol (0.26 [0.19-0.33]), and ACTH (0.26 [0.19-0.32]).

Conclusions

LH is followed by T with a delay of 60 minutes in healthy older men. Men with a strong LH-T relationship had more favorable body composition, inflammatory markers, LH levels, and LH-T feedforward synchrony. We observed positive correlations between T and TSH, cortisol, and ACTH.

Prolactin Increases the Frequency of Follicular T Helper Cells with Enhanced IL21 Secretion and OX40 Expression in Lupus-Prone MRL/lpr Mice

Systemic lupus erythematosus is characterized by high levels of IgG class autoantibodies that contribute to the pathophysiology of the disease. The formation of these autoantibodies occurs in the germinal centers, where there is cooperation between follicular T helper cells (T_FH) and autoreactive B cells. Prolactin has been reported to exacerbate the clinical manifestations of lupus by increasing autoantibody concentrations. The objective of this study was to characterize the participation of prolactin in the differentiation and activation of T_FH cells, by performing in vivo and in vitro tests with lupus-prone mice, using flow cytometry and real-time PCR. We found that T_FH cells express the long isoform of the prolactin receptor and promoted STAT3 phosphorylation. Receptor expression was higher in MRL/lpr mice and correlative with the manifestations of the disease. Although prolactin does not intervene in the differentiation of T_FH cells, it does favor their activation by increasing the percentage of T_FH OX40⁺ and T_FH IL21⁺ cells, as well as leading to high serum concentrations of IL21. These results support a mechanism in which prolactin participates in the emergence of lupus by inducing overactive T_FH cells and perhaps promoting dysfunctional germinal centers.

Carbohydrate-rich Meals Have no Impact on Post-prandial Lipid Parameters in Indians with Subclinical and Overt Primary Hypothyroidism

BACKGROUND AND AIMS

The impact of altered cholesterol metabolism on post-prandial lipids in Indians with hypothyroidism is not known. This study evaluated the impact of overt primary hypothyroidism (OPH) and subclinical hypothyroidism (ScH) on post-prandial lipids after a standardised, carbohydrate-rich, mixed meal.

METHODS

Endocrinology outpatients were screened for possible inclusion into the study. Patients >18 years of age with hypothyroidism who were not taking levothyroxine and who did not present with any comorbidities underwent biochemical evaluation following a carbohydrate-rich, mixed meal. Assessments included total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein-cholesterol (HDL-C), triglycerides, lipoprotein-A (Lp-A), apolipoprotein-A1 (apo-A1), apolipoprotein-B (apo-B), insulin and fasting glucose. Assessments were carried out 1 hour, 2 hours and 4 hours after the meal. Patients were compared against healthy matched controls recruited from healthcare professionals in the hospital (asymptomatic and apparently healthy nursing staff, reception staff and ward staff).

RESULTS

Data from 194 patients (161 with ScH and 33 with OPH) and 40 euthyroid controls were analysed. Anthropometry, body mass index, glycaemia and insulin resistance were comparable among patients with OPH and ScH, and controls. LDL-C and Lp-A were significantly higher in those with OPH, compared with ScH and controls, at baseline, 1 hour, 2 hours and 4 hours after mixed meal consumption (all p<0.05). There was progressive and similar decline in post-prandial TC, LDL-C and Lp-A in all three groups. Triglycerides were similar among the OPH, ScH and control groups, both in fasting and post-prandial state, with a progressive and similar increase in post-prandial triglycerides in all three groups.

CONCLUSION

This study demonstrated that severity of hypothyroidism had no impact on post-prandial TC, LDL-C and Lp-A. In addition, hypothyroidism had no impact on post-prandial triglycerides. Therefore, we conclude that lipid profile can be reliably estimated in a non-fasting state in individuals with ScH and OPH.

Hyperprolactinemia in clinical non-functional pituitary macroadenomas: A STROBE-compliant study

Hyperprolactinemia is a prevalent endocrine disorder presented in patients with non-functional pituitary adenomas (NFPAs). However, the mechanism involved in hyperprolactinemia in NFPA is not fully illustrated. The current study aims to investigate predictors for hyperprolactinemia in NFPA via analyzing relevant clinical features. Thus, in this study, a cohort of 214 cases with integrated medical records was retrospectively analyzed concerning clinical, pathological, and endocrinological studies before and after surgery.Hyperprolactinemia happened in 93 cases (43.5%). Women (adjust odds ratio [OR] = 3.093; P < .01), age of patients (adjust OR = 0.951; P < .01), and serum free tetraiodothyronine (FT4) level (adjust OR = 0.882; P = .02) were independent predictors for developing preoperative hyperprolactinemia. Tumor size and hypopituitarism had no impact on hyperprolactinemia. During a median follow-up of 43.5 (range, 22-80) months, 83.9% patients with preoperative hyperprolactinemia experienced prolactin (PRL) normalization. Preoperative PRL level (adjusted OR = 1.741, P = .03) was the exclusive predictor for PRL normalization after adjusting for tumor volume, preoperative serum FT4 concentration, and postoperative residual. The PRL normalization rate of patients with lower PRL level (<2.35-fold upper limit of normal range) was 95.2% and decreased to 65.5% for patients with higher PRL level.In conclusion, our results suggest existence of potentially alternative mechanisms underlying hyperprolactinemia in NFPAs, like the discrepancy of sex and age and the negative feedback of FT4. Preoperative PRL is a predictor for postoperative PRL normalization, which is of clinically relevant for postoperative management of NFPAs.

Role of hypothyroidism and associated pathways in pregnancy and infertility: Clinical insights

Thyroid disorders are the most common endocrine problems in women. In most of the cases, thyroid can lead to infertility or miscarriages. The etiology of infertility is multifactorial with thyroid disorders as the most common presenting factor, hypothyroidism in particular. Infertility in women can lead to emotional and psychological stress. The prevalence of hypothyroidism during pregnancy is estimated to be 0.3%–0.5%. Hypothyroidism and hyperthyroidism can result in menstrual irregularities and anovulatory cycles, thus affecting the fertility. There is a significant high prolactin (PRL) level in infertile women with hypothyroidism when compared to euthyroid patients, indicating the relation between hypothyroidism and hyperprolactinemia. The amount of thyrotropin releasing hormone (TRH) from the hypothalamus is markedly increased by inhibition of pyroglutamyl peptidase II, the enzyme catalyzing TRH. The increased TRH in hypothyroidism causes increased thyroid-stimulating hormone and PRL secretion by pituitary, leading to infertility and galactorrhea. In recent years, a neuropeptide called kisspeptin, encoded by Kiss1 gene, a potent stimulus for GnRH secretion, has been recognized, which suggests a future direction of treatment with kisspeptin and benefits the fertility induction among hyperprolactinemic infertile patients. Untreated hypothyroidism during pregnancy can lead to subfertility, fetal deaths, premature deliveries, and abortions. Therefore, women planning for pregnancy and infertile women should be assessed for thyroid hormones and serum PRL.

Biochemical diagnosis in prolactinomas: some caveats

Prolactinomas are the most frequently seen pituitary adenomas in clinical practice. A correct biochemical diagnosis of hyperprolactinemia is a prerequisite for further investigation but may be hampered by analytical difficulties as well as a large number of potentially overlapping conditions associated with increased prolactin levels. Suspicion should rise in patients whose symptoms and biochemical results do not match. Assay problems, macroprolactinemia, and high-dose hook effect are discussed as possible reasons for false positive or false negative prolactin levels. Physiological and pathological causes of hyperprolactinemia and their implications for interpreting prolactin results are reviewed.

Assessment of subclinical hypothyroidism for a clinical score and thyroid peroxidase antibody: a comparison with euthyroidism grouped by different thyroid-stimulating hormone levels

Background

Subclinical hypothyroidism (SCH) might have many symptoms of hypothyroidism. The controversy appears to lower the level of thyroid-stimulating hormone (TSH) and group subjects with TSH of more than 3 or even 2.5 mIU/L as SCH subjects.

Objectives

To assess SCH subjects both clinically using Zulewski clinical score and biochemically and to evaluate whether the euthyroid subjects with high-normal TSH (HNT) have any clinical symptom or subnormal biochemical finding.

Methods

A prospective cross-sectional study of 233 subjects, 67 with SCH and 166 euthyroidism, was conducted. Euthyroid subjects were divided according to the level of TSH as HNT (>2.5 mIU/L) and low-normal TSH (0.5–2.5 mIU/L). The subjects were examined for clinical feature including Zulewski clinical score and biochemical evaluations including thyroid peroxidase antibody (TPO-Ab) titer. The comparisons between groups were assessed using independent sample t test, and correlations between variables were evaluated using Pearson correlation.

Results

A significantly higher clinical score and higher frequencies of symptoms were found in the SCH group compared to the euthyroid group. The most frequent symptom was fatigue. Euthyroid subjects with HNT were found to have higher TPO-Ab titers than those with low-normal TSH, P < 0.05. The Zulewski clinical score was positively correlated with TSH and TPO-Ab titer but negatively correlated with the FT4 level, P < 0.05.

Conclusions

Zulewski clinical score is higher in SCH subjects compared to euthyroid subjects and can aid in assessing SCH subjects. A significant correlation exists between Zulewski clinical score and each of the TSH, FT4, and TPO-Ab titer levels. The frequency of TPO-Ab positivity is high in SCH. Additionally, euthyroid with higher TSH levels has higher level of TPO-Ab titer but not higher clinical score.

Hyperprolactinaemia

Hyperprolactinaemia is one of the most common problems in clinical endocrinology. It relates with various aetiologies (physiological, pharmacological, pathological), the clarification of which requires careful history taking and clinical assessment. Analytical issues (presence of macroprolactin or of the hook effect) need to be taken into account when interpreting the prolactin values. Medications and sellar/parasellar masses (prolactin secreting or acting through “stalk effect”) are the most common causes of pathological hyperprolactinaemia. Hypogonadism and galactorrhoea are well-recognized manifestations of prolactin excess, although its implications on bone health, metabolism and immune system are also expanding. Treatment mainly aims at restoration and maintenance of normal gonadal function/fertility, and prevention of osteoporosis; further specific management strategies depend on the underlying cause. In this review, we provide an update on the diagnostic and management approaches for the patient with hyperprolactinaemia and on the current data looking at the impact of high prolactin on metabolism, cardiovascular and immune systems.

Thyroid gland and brain: Enigma of Hashimoto's encephalopathy

The versatile clinical manifestations of the Hashimoto's chronic autoimmune thyroiditis often include psycho-neurological disorders. Although hypothyroidism disturbs significantly the ontogenesis and functions of central nervous system, causing in severe cases of myxedema profound impairment of cognitive abilities and even psychosis, the behavioral, motor and other psychoneurological disorders accompany euthyroid and slightly hypothyroid cases and periods of Hashimoto's disease as well, thus constituting the picture of so called "Hashimoto's encephalopathy". The entity, although discussed and explored for more than 50 years since its initial descriptions, remains an enigma of thyroidology and psychiatry, because its etiology and pathogenesis are obscure. The paper describes the development of current views on the role of thyroid in ontogeny and functions of brain, as well as classical and newest ideas on the etiology and pathogenesis of Hashimot's encephalopathy. The synopsis of the world case reports and research literature on this disorder is added with authors' own results obtained by study of 17 cases of Hashimoto's thyroiditis with schizophrenia-like clinical manifestations. The relation of the disease to adjuvant-like etiological factors is discussed. Three major mechanistic concepts of Hashimoto's encephalopathy are detailed, namely cerebral vasculitis theory, hormone dysregulation theory and concept, explaining the disease via direct action of the autoantibodies against various thyroid (thyroperoxidase, thyroglobulin, and TSH-receptor) and several extrathyroid antigens (alpha-enolase and other enzymes, gangliosides and MOG-protein, onconeuronal antigens) - all of them expressed in the brain. The article demonstrates that all above mentioned concepts intermingle and prone to unification, suggesting the unified scheme of pathogenesis for the Hashimoto's encephalopathy. The clinical manifestations, criteria, forms, course, treatment and prognosis of Hashimoto's encephalopathy and its comorbidity to other diseases - are also discussed in brief. The relation between Hashimoto's encephalopathy and non-vasculitis autoimmune encephalomyelitides of paraneoplastic and non-paraneoplastic origin is emphasized [1 figure, bibliography - 200 references].

Thyroid Symptomatology across the Spectrum of Hypothyroidism and Impact of Levothyroxine Supplementation in Patients with Severe Primary Hypothyroidism

OBJECTIVE

This study aimed to determine the clinical and biochemical profile of patients with severe primary hypothyroidism (SPH) (TSH ≥40 μIU/ml) as compared to milder forms of hypothyroidism and document improvement in hypothyroidism symptoms in SPH.

METHODS

Thyroid symptomatology and biochemistry were evaluated in SPH, non-severe overt primary hypothyroidism (NSOPH; TSH <40 μIU/ml), subclinical hypothyroidism (ScH) and healthy controls. A total of 598 consecutive patients of hypothyroidism were screened of which 461 patients' data were analyzed (91 SPH, 130 NSOPH and 240 ScH). Thyroid symptomatology was re-evaluated at 12 weeks follow-up in SPH following restoration of euthyroidism with levothyroxine.

RESULTS

The median (interquartile range) age of patients was 35 (28-42) years with 91.6% female. The commonly noted symptomatology were shortness of breath (93.4%) and fatigueability (91.2%) in SPH, fatigueability (68.46%) and limbs swelling (43.07%) in NSOPH, and fatigueability (56.67%) and shortness of breath (32.92%) in ScH. All symptomatology were significantly higher in SPH. Delayed tendon reflex, carpel tunnel syndrome and meno-metrorrhagia were exclusive in SPH. Occurrence of menstrual irregularities was 73.62%, 28.46% and 16.25% in SPH, NSOPH and ScH, respectively. SPH patients had significantly higher cholesterol and triglycerides. There was significant improvement in symptomatology, reduction in body weight (-2.11 kg), improvement in hemoglobin (+0.64 g/L) with fall in total cholesterol (-18.96%), LDL-cholesterol (-23.46%) and triglycerides (-13.53%) following euthyroidism restoration in subjects with SPH. Common residual symptoms were fatigue (10%), poor memory (8%) and menstrual irregularities (6%).

CONCLUSION

Thyroid symptomatology differs significantly across spectrum of hypothyroidism, being significantly worse in SPH. Euthyroidism restoration is associated with reversal of majority of thyroid symptomatology.

Management of prolactinoma: a survey of endocrinologists in China

Objective To assess the current management of prolactinoma among endocrinologists in China. Methods An online survey of a large sample of endocrinologists was conducted in China. The questionnaire included 21 questions related to controversial issues about the management of prolactinomas. Doctors in the endocrinology department of a university-affiliated hospital or a comprehensive secondary hospital in 12 cities from East, West, South, North and Middle China were surveyed. Results A total of 290 valid questionnaires were collected, and the response rate was 40%. When hyperprolactinemia occurred, 97% of the respondents would test thyroid-stimulating hormone routinely. 22% of the respondents considered that prolactin levels <100 ng/mL exclude the presence of a prolactinoma. Only 9% of the respondents believed that prolactin >250 ng/mL could occur in all the following situations as macroprolactinoma, mircoprolactinoma, macroprolactinemia and drug-induced hyperprolactinemia. Surgery was not recommended by 272 (94%) endocrinologists as the first choice for treating microprolactinomas. 58% and 92% of endocrinologists would start drug treatment for microprolactinomas and macroprolactinomas at diagnosis. 70% and 40% chose to withdraw treatment after 2-3 years of prolactin normalization in microprolactinomas and macroprolactinomas. In case of pregnancy, 57% of the respondents considered bromocriptine as choice for women patients. Drug discontinuation after pregnancy was advocated in 63% and 27% for microprolactinoma and macroprolactinoma. Moreover, 44% of endocrinologists believed that breastfeeding was allowable in both micro- and macroprolactinoma. Conclusion This is the first study to investigate the management of prolactinomas among endocrinologists in China. We found that the current clinical treatment was not uniform. Therefore, it is necessary to strengthen the training of endocrinologists to improve clinical diagnosis and treatment practices.

Hyperprolactinemia with Galactorrhea Due to Subclinical Hypothyroidism: A Case Report and Review of Literature

Hyperprolactinemia is a common finding in primary hypothyroidism, but increased prolactin in the setting of subclinical hypothyroidism (SCH) has been scarcely reported in the literature. This is a rare case of hyperprolactinemia due to SCH that resolved with thyroid hormone replacement therapy. The patient was not on any medications known to cause hyperprolactinemia but she was using isoniazid for her latent tuberculosis. Isoniazid therapy may explain breast pain, but there is no reported relationship between isoniazid use causing subclinical hypothyroidism and hyperprolactinemia. A literature review reveals that few cases of galactorrhea associated with subclinical hypothyroidism have been reported. Similar to the reported cases in the literature, our patient’s thyroid stimulating hormone (TSH) and prolactin levels returned to normal with levothyroxine therapy.

Estimation of serum prolactin levels and determination of prevalence of hyperprolactinemia in newly diagnosed cases of subclinical hypothyroidism

Background:

Hyperprolactinemia is a common endocrine disorder involving hypothalamic–pituitary axis. Prolactin (PRL) secretion is stimulated by dopamine antagonism and thyroid-releasing hormone. Hyperprolactinemia has been reported in subclinical hypothyroidism (SCH) but results are markedly variable and studies on SCH are very few. The objective of this study was to find out prevalence of hyperprolactinema in newly diagnosed subclinical hypothyroid patients.

Materials and Methods:

In this cross-sectional study, serum PRL levels of 150 newly diagnosed subclinical hypothyroid patients were determined using electrochemiluminescence method.

Results:

Raised PRL levels were found in 18 (%) patients with SCH. There was positive correlation between serum thyroid-stimulating hormone and PRL levels. Prevalence of infertility was significantly higher with presence of hyperprolactinemia than normoprolactinemia in subclinical hypothyroid patients.

Conclusion:

Routine prolactin estimation and subsequent treatment is required in patients with subclinical hypothroidism.

Hyperprolactinemia in Children with Subclinical Hypothyroidism

Prevalence of hyperprolactinemia in children with subclinical hypothyroidism (ScH) is not known. This study aimed to determine the occurrence and predictors of hyperprolactinemia in euthyroid children and in children with ScH and overt primary hypothyroidism (OPH). Serum prolactin levels were estimated in consecutive children <18 years of age undergoing thyroid function evaluation and diagnosed to have normal thyroid function, ScH, or OPH. Children with pituitary adenomas, secondary hypothyroidism, multiple pituitary hormone deficiency, comorbid states, and drug-induced hyperprolactinemia were excluded. From the initially screened 791 children, hormonal data from 602 children who fulfilled all criteria were analyzed. Seventy-one (11.79%) of these had ScH, and 33 (5.48%) had OPH. Occurrence of hyperprolactinemia was highest in the OPH group (51.51%), followed by ScH (30.98%) and euthyroid children (4.41%) (p<0.001). Median (25th-75th percentiles) levels for prolactin in euthyroid, ScH, and OPH children were 13.3 (9.4-17.95), 19.15 (15.97-30.12), and 28.86 (17.05-51.9) ng/mL, respectively (p<0.001). In children, prolactin levels were comparable in males and females. An age-related increase in serum prolactin was noted in euthyroid children, which was statistically significant in post-pubertal (16-18 years) children. Area under the curve for thyroid stimulating hormone (TSH) in predicting hyperprolactinemia in children was 0.758 (95% confidence interval: 0.673-0.829; p<0.001). TSH ≥4.00 mIU/L had a sensitivity of 69.4% and specificity of 77.6% in detecting hyperprolactinemia. Hyperprolactinemia is common in children with ScH and OPH. TSH ≥4.00 mIU/L has a good sensitivity and specificity in predicting hyperprolactinemia in children. More studies are needed to establish if hyperprolactinemia should be an indication for treating ScH in children.

Subclinical hypothyroidism: Is it important in intracytoplasmic sperm injection cycles?

OBJECTIVE

To compare intracytoplasmic sperm injection (ICSI) outcomes of women with subclinical hypothyroidism with those of euthyroid women.

MATERIALS AND METHODS

A retrospective case-control study was conducted. Out of 2529 ICSI cycles evaluated, 41 women with hypothyroidism, 28 women with hyperthyroidism, and 128 women with subclinical hyperthyroidism were excluded, and 2336 cycles were analyzed. Women were identified as having subclinical hypothyroidism (case group, n=105) in the presence of a thyroid-stimulating hormone level >4.5 mU/L and normal free T4 and compared with euthyroid controls (n=2231).

RESULTS

The mean age, body mass index, day 3 follicle-stimulating hormone level, and antral follicle count of the study patients were similar to the control group (p>0.5). The cycle cancellation rate of the study group was similar to the control group (13.3% vs. 7.6%, p=0.1). The clinical pregnancy rate was 21.2% in the study group, which was significantly lower than the 35.8% in the control group (p=0.04). The take-home baby rate was also significantly lower in the study group compared with the control groups (13.5% vs. 31.4% respectively, p=0.01).

CONCLUSION

Both the clinical pregnancy rate and the take-home baby rate is lower in women with subclinical hypothyroidism at the time of ICSI cycle.

A 2016 clinical practice pattern in the management of primary hypothyroidism among doctors from different clinical specialties in New Delhi

BACKGROUND

This study aimed to document practices in managing hypothyroidism among doctors in New Delhi, with special focus on subclinical hypothyroidism, pregnancy, and old age, and to compare it with global practices.

METHODS

During an academic program attended by 394 doctors, all participants were given a questionnaire designed based on thyroid practices survey done by Burch et al. to evaluate the practice patterns. Questions were based on evaluating doctor's preferred choices in diagnosis, therapy, and follow-up of hypothyroidism in different scenarios.

RESULTS

Responses from 308 questionnaires (general physicians [n = 204], obstetricians [n = 51], pediatricians [n = 27], surgeons [n = 12], endocrinologists [n = 10], and others [n = 4]) were analyzed. In the evaluation of 52-year-old female patient with primary hypothyroidism, 52% doctors would prefer thyroid ultrasonography, comparable to global rates. Nearly 96.1% doctors would have initiated levothyroxine, with a large majority of doctors (83.77%) preferred using branded levothyroxine. About 58.74% doctors preferred gradual restoration of euthyroidism. Levothyroxine dose of 25 mcg was the most preferred increment dose (46.07%) during follow-up, with 6 weekly being the most frequent dose adjustment frequency (41.57%). Most preferred target thyroid-stimulating hormone (TSH) in the 52-year-old female patient was 2.5-4.99 mU/L (63.96%), 25-year-old female patient was 1-2.49 mU/L (53.90%), and in 85-year-old female was 2.5-4.99 mU/L (45.45%). Only 68% of doctors in our study preferred keeping TSH <2.5 mU/L during the first trimester of pregnancy, in contrast to global trends of 95% (P < 0.001).

CONCLUSION

There was a disproportionately high use of ultrasonography in hypothyroidism management, near exclusive preference for branded levothyroxine, widespread use of age-specific TSH targets, and low threshold for treating mild thyroid failure, a highly variable approach to both rates and means of restoring euthyroidism for overt primary hypothyroidism. There is a need for spreading awareness regarding TSH targets in pregnancy.