The effects of drugs on endocrine function

Overt Primary Hypothyroidism in an Industrial Area in São Paulo, Brazil: The Impact of Public Disclosure

Background: Primary hypothyroidism (PH) is the most common thyroid pathology. Purpose: to evaluate the impact of public disclosure of an unexpected number of PH cases on the frequency of patients seeking medical evaluation for endocrinological diseases. Methods: data on 6306 subjects (3356 living in the surroundings of a petrochemical complex and 2950 in a control region) were collected over a 15-year time span. Thyroid function was determined by serum levels of triiodothyronine, thyroxine, free thyroxine and thyrotrophin. Antithyroglobulin and antithyroperoxidase antibodies and sonographic scans of the thyroid were performed in all patients. The data were analyzed via log-linear models to compute odds and odds ratios. Results: An increasing trend in the odds of PH was detected along the observation period with greater slope in the study region than in the control region. The odds of PH in the post-disclosure period (2002 to 2004) are greater than the corresponding ones in the pre-disclosure period (1989 to 2001). Conclusions: This study shows that living in the surroundings of a petrochemical complex may be an important risk factor for PH for both adults and children. Furthermore, public disclosure of such risk factor contributes to the awareness of the problem and to the possibility of an early diagnosis.

The impact of the CAG repeat polymorphism of the androgen receptor gene on muscle and adipose tissues in 20-29-year-old Danish men: Odense Androgen Study

BACKGROUND

The number of CAG repeats (CAG(n)) within the CAG repeat polymorphism of the androgen receptor gene correlates inversely with the transactivation of the receptor.

OBJECTIVE

To examine the impact of CAG(n) on muscle, fat distribution, and circulating androgen levels. Design, settings and participants Population-based, cross-sectional study of 783 Danish men aged 20-29 years.

METHODS

Genotyping was performed in 767 men. Areas of thigh and lower trunk muscle (muscle(thigh) and muscle(lower trunk)), subcutaneous adipose tissues (SAT(thigh) and SAT(lower trunk)), and deep adipose tissues (i.m. and visceral) were measured in 393 men by magnetic resonance imaging (MRI). Lean body mass (LBM) and fat mass (FM) were measured in all men by whole body dual-energy X-ray absorptiometry (DEXA). The absolute areas acquired by MRI were the main outcomes. The absolute DEXA measurements and relative assessments of both modalities were considered as the secondary outcomes. Results CAG(n) (range: 10-32) correlated inversely with absolute muscle(thigh) (r=-0.108), absolute muscle(lower trunk) (r=-0.132), relative muscle(thigh) (r=-0.128), relative muscle(lower trunk) (r=-0.126), relative LBM(lower extremity) (r=-0.108), and relative LBM(total) (r=-0.082), and positively with relative SAT(thigh) (r=0.137), relative SAT(lower trunk) (r=0.188), relative FM(lower extremity) (r=0.107), and relative FM(total) (r=0.082). These relationships remained significant, controlling for physical activity, smoking, chronic disease, and age. CAG(n) did not correlate with any circulating androgen.

CONCLUSIONS

The CAG repeat polymorphism affects body composition in young men: absolute muscle(thigh) and absolute muscle(lower trunk) increase as CAG(n) decreases. Expressed relatively, muscle areas and LBM increase, while SAT and FM decrease as CAG(n) decreases. The polymorphism does not affect deep adipose tissues or circulating androgen levels in young men.

Visceral and subcutaneous adipose tissue assessed by magnetic resonance imaging in relation to circulating androgens, sex hormone-binding globulin, and luteinizing hormone in young men

CONTEXT

No large studies of young men have examined circulating sex hormones in relation to visceral and sc adipose tissues.

OBJECTIVE

The aim of this study was to investigate the role of visceral adipose tissue and sc adipose tissue on circulating sex hormones and the impact of obesity on sex hormone reference intervals.

DESIGN, SETTING, AND PARTICIPANTS

Population-based study of 783 Danish 20- to 29-yr-old men was performed using dual-energy x-ray absorptiometry in all men and magnetic resonance imaging in 406 men.

MAIN OUTCOME MEASURES

Total, bioavailable, and free testosterone, dihydrotestosterone (DHT), total and bioavailable estradiol, SHBG, and LH were measured.

RESULTS

In multiple regressions, visceral adipose tissue was an independent, inverse correlate of bioavailable and free testosterone. Subcutaneous adipose tissue correlated negatively with SHBG and positively with bioavailable estradiol adjusted for total testosterone. Both visceral adipose tissue and sc adipose tissue correlated inversely with total testosterone and DHT. Adjusting for SHBG, only visceral adipose tissue remained significantly correlated. Low total testosterone in viscerally obese men was not accompanied by increased LH. The androgen reference intervals were significantly displaced toward lower limits in obese vs. nonobese men (total testosterone: 8.5-29.3 vs. 12.5-37.6 nmol/liter; bioavailable testosterone: 6.1-16.9 vs. 7.6-20.7 nmol/liter; free testosterone: 0.23-0.67 vs. 0.29-0.78 nmol/liter; and DHT: 0.63-2.5 vs. 0.85-3.2 nmol/liter), whereas total estradiol (36.5-166 pmol/liter) and bioavailable estradiol (23.4-120 pmol/liter) reference intervals were not. In obese men, 22.9% had total testosterone less than 12.5 nmol/liter.

CONCLUSIONS

Visceral adipose tissues correlate independently with bioavailable and free testosterone in young men. The inverse relationship between total testosterone and sc adipose tissue seems to be accounted for by variations in SHBG. The reference intervals for total testosterone, bioavailable testosterone, free testosterone, and DHT are displaced toward lower limits in obese men.

Pattern of endocrinal changes in patients with sexual dysfunction

INTRODUCTION

Many patients with endocrinal changes (endocrinopathy) have some degrees of sexual dysfunction that necessitate assessment and treatment.

AIM

To assess the prevalence, and identify the pattern, of endocrinopathy in patients with sexual dysfunction in our community.

METHODS

A total of 1,248 male patients with sexual dysfunction were enrolled in this study. Patients were screened for erectile dysfunction (ED) and sexual desire by the erectile function and the sexual desire domains of the International Index of Erectile Function (IEEF). Patients underwent routine laboratory investigations as well as total testosterone and prolactin assessment. All patients were referred to an endocrinologist for clinical and biochemical assessment of their endocrine function. The evaluation consisted of comprehensive history taking, physical examination, and, as needed, laboratory investigations.

RESULTS

Mean ages+/-SD were 51.9+/-12.2 and 52.3+/-11.7 years for patients with and without endocrinopathy, respectively. Of the study population, 23.8% had endocrinopathy. The most frequent endocrinal changes were low testosterone level (15%), hyperprolactinemia (13.7%), and hypothyroidism (3.1%). There were significant associations between endocrinopathy and obesity, smoking, low desire, and premature ejaculation (P<0.05 for each). Also, significant associations were found between low desire and low testosterone level, hyperprolactinemia, and hypothyroidism (P<0.05 for each). Hyperprolactinemia was significantly associated with premature ejaculation (P<0.05) but not with low testosterone level (P>0.05). There was no significant association between endocrinopathy and age, cigarette smoking (number and duration), and ED (duration, severity, type of onset, and progression) (P>0.05 for each).

CONCLUSION

Endocrinopathy is not a rare condition among ambulatory patients with sexual dysfunction. This study provides a quantitative estimate of endocrinopathy in ambulatory patients with sexual dysfunction.

Gynaecomastia with hypergonadotrophic hypogonadism and Leydig cell insufficiency in recipients of high-dose chemotherapy or chemo-radiotherapy

Late side-effects of stem cell transplantation include hypogonadism with infertility and sexual dysfunction, but gynaecomastia is less well recognised. We report five cases of gynaecomastia with features of hypergonadotrophic hypogonadism (primary testicular failure), who received either a TBI/cyclophosphamide conditioned allograft (n = 3) or a BEAM autograft (n = 2). Patients receiving an allograft had gynaecomastia, Leydig cell insufficiency (LCI) diminished libido and erectile dysfunction. Surgery was required in one case, while in two cases the gynaecomastia resolved spontaneously after 6 months. Two patients also had gynaecomastia and sexual dysfunction, severe hypogonadism, very low testosterone levels and marked hyperprolactinaemia following autoBMT. Both responded well to testosterone replacement therapy (TRT). As a group, all patients had primary testicular failure and all except one, had LCI (compensated or frank). However, there was no correlation between the severity of gynaecomastia and the degree of endocrine dysfunction. This preliminary study is the first to suggest that gynaecomastia, due to primary hypogonadism and LCI, may be a significant complication of myeloablative conditioning therapy. Therefore gynaecomastia in BMT recipients must always be treated as a pathological entity as it may be the external manifestation of a complex endocrine pathology. It is a potentially treatable condition. Although spontaneously reversible, some patients may require TRT or even surgery. We recommend comprehensive endocrine testing in conjunction with a reproductive endocrinologist and prompt intervention to alleviate embarrassment and anxiety in afflicted BMT recipients.

Population screening for autoimmune thyroid disease

Whether or not healthy adults in the community would benefit from screening for autoimmune thyroid disease is controversial. Although the prevalence of unsuspected overt thyroid disease is low, a significant proportion of subjects tested will have evidence of mild thyroid failure or excess. This article assesses whether subclinical thyroid disease is of sufficient clinical importance to warrant screening and, once detected and confirmed, to justify therapy. Population screening for autoimmune thyroid disease is assessed against recently revised screening criteria, using data from epidemiologic studies. Recommendations are proposed that may be applied in any iodine-replete community.

The role of the hypothalamic-pituitary-adrenal axis in rheumatoid arthritis

It has become clear that there is a bidirectional communication between the neuroendocrine and the immune system and that both systems influence each other and interact under physiological conditions and in response to inflammatory stimuli. The hypothalamic-pituitary axis plays an important role in regulating and controlling immune responses and dysfunction of the axis has been implicated in the pathogenesis of rheumatoid arthritis (RA). Corticotrophin-releasing hormone (CRH), one of the main hormones of the axis, is also released extra-hypothalamically, peripherally at the site of inflammation and may modulate inflammatory responses locally. In this chapter we will discuss the role of the hypothalamic-pituitary-adrenal (HPA) axis and peripheral CRH, its influences on immune function and what is known about the possible pathogenetic role of the HPA axis and peripheral CRH in RA.

Relationship between psychotropic drugs and thyroid function: a review

Some widely used psychoactive drugs, such as tricyclic antidepressants and antipsychotic phenothiazines exhibit iatrogenic effects on the thyroid. These side effects may arise from interactions at different steps of thyroid hormone biosynthesis. These drugs can induce a change in iodine capture by thyroid cells or can complex iodine, making it unavailable for thyroid hormone synthesis and thus decreasing thyroid hormone blood levels; they can also inhibit thyroid peroxidase activity and thus T3 and T4 synthesis or enhance deiodination of T4 to T3 or to Rt3 by stimulation of deiodinase activity. Moreover, tricyclic antidepressants interfere with the hypothalamic-pituitary-thyroid axis via the noradrenergic or serotonergic systems and might therefore decrease T4 or T3 blood levels, respectively. Phenothiazines can induce autoimmune hypothyroidism, as shown by an increase in the expression of the major histocompatibility complex antigen and by a production of antithyroglobulin or antithyroperoxidase antibodies. However, all these mechanisms are only speculative in humans, as they have only been demonstrated in vitro or in animal experiments. Clinically, thyroid function and affective disorders are closely linked. On one hand, the therapeutic response to antidepressants could be influenced by the thyroid status; on the other hand, the larger the thyroxin decrease induced by antidepressants, the better the therapeutic effect might be. Moreover, cotreatment with thyroid hormones and antidepressant drugs could allow either a decrease in the rate of treatment failure or a faster recovery from depression. As antipsychotic or antidepressant treatments are administered over long periods in humans, their thyroid toxic effects must be taken seriously.