Abnormal testicular function in men with primary hypothyroidism

Thyroid impairment and male fertility: a narrative review of literature

PURPOSE

To evaluate the effect of thyroid function on male fertility, focusing on hypo- and hyperthyroidism.

METHODS

A PubMed/MEDLINE, Web of Science, and Scopus research was performed. Original studies in English published online up to 31 May 2023 were selected and reviewed. The final reference list was defined based on the relevance of each paper to the scope of this review.

RESULTS

The available data in animals (31 studies) and human (26 studies) showed conflicting results. However, thyroid dysfunction altered erection and ejaculation both in animal models than in men.

CONCLUSION

Both hypothyroidism and hyperthyroidism seem to cause ejaculation and erectile dysfunction. Hence, Guidelines recommend against the systematic screening for thyroid disorders in the men in sub-fertile couples, but only in men with ejaculation and erectile dysfunction and/or altered semen parameters.

Autoimmune Thyroiditis Mitigates the Effect of Metformin on Plasma Prolactin Concentration in Men with Drug-Induced Hyperprolactinemia

Metformin inhibits the secretory function of overactive anterior pituitary cells, including lactotropes. In women of childbearing age, this effect was absent if they had coexisting autoimmune (Hashimoto) thyroiditis. The current study was aimed at investigating whether autoimmune thyroiditis modulates the impact of metformin on the plasma prolactin concentration in men. This prospective cohort study included two groups of middle-aged or elderly men with drug-induced hyperprolactinemia, namely subjects with concomitant Hashimoto thyroiditis (group A) and subjects with normal thyroid function (group B), who were matched for baseline prolactin concentration and insulin sensitivity. Titers of thyroid peroxidase and thyroglobulin antibodies, levels of C-reactive protein, markers of glucose homeostasis, concentrations of pituitary hormones (prolactin, thyrotropin, gonadotropins, and adrenocorticotropic hormone), free thyroxine, free triiodothyronine, testosterone, and insulin growth factor-1 were measured before and six months after treatment with metformin. Both study groups differed in titers of both antibodies and concentrations of C-reactive protein. The drug reduced the total and monomeric prolactin concentration only in group B, and the impact on prolactin correlated with the improvement in insulin sensitivity and systemic inflammation. There were no differences between the follow-up and baseline levels of the remaining hormones. The results allow us to conclude that autoimmune thyroiditis mitigates the impact of metformin on prolactin secretion in men.

Testosterone deficiency in male organ transplant recipients

Testosterone deficiency is known to affect men with increasing incidence throughout their lifespan. The clinical manifestations of testosterone deficiency, in turn, negatively impact men's quality of life and perception of overall health. The interaction of chronic systemic disease and androgen deficiency represent an area for potential intervention. Here, we explore the topic of testosterone deficiency amongst men with end-stage organ failure requiring transplantation in order to elucidate the underlying pathophysiology of androgen deficiency of chronic disease and discuss whether intervention, including testosterone replacement and organ transplantation, improve patients' outcomes and quality of life.

Chronic Immune-Mediated Orchitis Is the Major Cause of Acquired Non-obstructive Azoospermia in Dogs

Azoospermia, the lack of spermatozoa in the ejaculate, is the most common finding in infertile but otherwise healthy male dogs and represents an increasing reproductive health issue in men, too. The diagnosis can be further classified as non-obstructive azoospermia and obstructive azoospermia due to an obstruction of the deferent ducts. Although non-obstructive azoospermia comprises more than half of azoospermic cases in men and is a common cause of infertility in the male dog, knowledge of the underlying etiology and pathophysiology is still strongly limited, and much uncertainty exists about the true incidence and possible treatment options. Therefore, this study aims to investigate and characterize infertile canine patients in detail by combining results of andrological examinations (clinical parameters, semen analysis, bacterial examination of semen, and Brucella canis serology), endocrine analysis (luteinizing hormone, testosterone, estradiol-17ß, and thyroid function), analysis of the alkaline phosphatase in seminal plasma, and histological assessment of testicular biopsies of 10 azoospermic dogs. Our results not only verify non-obstructive etiology for 9/10 cases of canine azoospermia but also further identified significant histopathological changes of the testicular tissue with severely disrupted spermatogenesis, including fibrotic remodeling, vacuolization, Sertoli-cell-only syndrome, tubular shadows, and an increase of the interstitial and vascular area. In addition, three dogs showed local and six dogs generalized immune-cell infiltration, indicating chronic immune-mediated orchitis. Only in one case (no. 1) that no immune cells were found, and obstructive azoospermia was suspected due to low alkaline phosphatase activity. Furthermore, the detection of anti-thyroideal antibodies in two dogs indicates an autoimmune thyroid disease and a correlation between the occurrence of thyroidal disorders and azoospermia. Our results confirm previous findings and contribute additional evidence suggesting that chronic immune-mediated orchitis is the major cause of infertility in dogs. Further studies should focus on uncovering underlying inflammatory processes behind spermatogenic failure in these cases and identify possible treatment options to (re-)initialize spermatogenesis.

Comorbidities of male patients with sexual dysfunction in a psychiatry clinic: A study on industrial employees

BACKGROUND

Previous studies assessed the association of sexual dysfunction (SD) in cases of specific organic and psychiatric disorders separately as risk factors of SD, but the extent of association of various disorders in cases of SD was rarely evaluated. This study was conducted to assess almost all types of comorbidities to find out their effects on SD in male patients and to make complete diagnoses.

MATERIALS AND METHODS

All male patients aged between 18 and 60 years reporting with sexual problems to the psychiatry outpatient department were evaluated with Arizona sexual experiences scale (ASEX) for males. Their assessment included detailed medical and psychiatric history including medicine intake, physical and mental status examination. Relevant biochemical investigations were done including sex hormone assessment.

RESULTS

Among 104 males diagnosed as cases of SD according to the ASEX scale in 1 year period only 75 patients completed all the biochemical and hormonal assessments. It was observed that 38.67% were diagnosed as SD without any comorbidity, 25.33% had biochemical or hormonal or physical comorbidities, 21.33% had psychiatric comorbidities and 14.67% had psychiatric as well as biochemical or hormonal or physical comorbidities (n = 75). The severity of SD was higher in the patients with comorbidity and the age of the patients predicted its severity.

CONCLUSION

All cases of SD should be assessed in detail for physical, biochemical, hormonal, and psychiatric comorbidities to treat them holistically. Psychiatrists should play a key role in assessing, diagnosing, treating, and referring them to the appropriate treatment provider.

Endocrinopathies and Male Infertility

Male infertility is approaching a concerning prevalence worldwide, and inflicts various impacts on the affected couple. The hormonal assessment is a vital component of male fertility evaluation as endocrine disorders are markedly reversible causatives of male infertility. Precise hormonal regulations are prerequisites to maintain normal male fertility parameters. The core male reproductive event, spermatogenesis, entails adequate testosterone concentration, which is produced via steroidogenesis in the Leydig cells. Physiological levels of both the gonadotropins are needed to achieve normal testicular functions. The hypothalamus-derived gonadotropin-releasing hormone (GnRH) is considered the supreme inducer of the gonadotropins and thereby the subsequent endocrine reproductive events. This hypothalamic–pituitary–gonadal (HPG) axis may be modulated by the thyroidal or adrenal axis and numerous other reproductive and nonreproductive hormones. Disruption of this fine hormonal balance and their crosstalk leads to a spectrum of endocrinopathies, inducing subfertility or infertility in men. This review article will discuss the most essential endocrinopathies associated with male factor infertility to aid precise understanding of the endocrine disruptions-mediated male infertility to encourage further research to reveal the detailed etiology of male infertility and perhaps to develop more customized therapies for endocrinopathy-induced male infertility.

Impact of dehydroepiandrosterone on thyroid autoimmunity and function in men with autoimmune hypothyroidism

Background Testosterone administration was found to have a protective effect on thyroid autoimmunity in men with autoimmune (Hashimoto's) thyroiditis. Objective The present study was aimed at assessing whether oral dehydroepiandrosterone affects thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity in men with subclinical hypothyroidism induced by Hashimoto's thyroiditis. Setting The study was conducted at Medical University of Silesia, Katowice, Poland. Method The study enrolled 32 elderly men with autoimmune hypothyroidism and low dehydroepiandrosterone-sulfate levels. Based on patient preference, the participants either received oral dehydroepiandrosterone (50 mg daily; n = 16) or remained untreated (n = 16). Apart from measuring antibody titers and hormone levels, we calculated baseline and post-treatment values of three structure parameters of thyroid homeostasis. Main outcome measure Serum titers of thyroid peroxidase and thyroglobulin antibodies. Results At baseline, there were no significant differences in the investigated parameters between both groups of men. All participants completed the study. Oral dehydroepiandrosterone increased dehydroepiandrosterone-sulfate and testosterone levels, as well as had a neutral effect on estradiol levels. The increase in dehydroepiandrosterone-sulfate correlated with treatment-induced changes in serum testosterone. Moreover, dehydroepiandrosterone reduced titers of thyroid peroxidase and thyroglobulin antibodies, decreased serum thyrotropin levels, reduced Jostel's thyrotropin index as well as increased thyroid's secretory capacity. Treatment-induced changes in thyroid antibody titers, thyrotropin levels, Jostel's thyrotropin index and thyroid's secretory capacity correlated with the increase in dehydroepiandrosterone-sulfate and testosterone levels. Conclusion The obtained results show that exogenous dehydroepiandrosterone may exert a beneficial effect on thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity in men with autoimmune thyroiditis and subclinical hypothyroidism.

Effect of Thyroxine Replacement on Leydig Cell and Sertoli Cell Function in Men with Hypothyroidism

CONTEXT

Thyroid hormones play an important role in reproductive and sexual function in both sexes. Comprehensive information on the ill-effects of hypothyroidism on Leydig cell, Sertoli cell and germ cell function is lacking in the existing literature.

AIMS

To investigate the effect of primary hypothyroidism and its treatment on testicular function - Sertoli cell, Leydig cells, seminal fluid and spermatozoa.

METHODS AND MATERIAL

This study was carried out as a descriptive study with a before-after study design in the endocrine department of a tertiary care hospital in South India. Forty treatment naïve, overtly primary hypothyroid, consenting male patients were included. Hormones assessed were free T3, free T4, thyroid stimulating hormone, follicle stimulating hormone [FSH], luteinizing hormone [LH], prolactin, testosterone, inhibin B[INHB], and insulin like factor 3[INSL3]. Semen analysis was done according to WHO 2010 guidelines in 37 subjects. Sexual function questionnaires like Androgen Deficiency in Aging Male [ADAM], and Arizona Sexual Experience Scale [ASEX] were used. After ensuring euthyroid state for consecutive 6 months with adequate dose of thyroxine sodium, reassessment of all parameters was done.

RESULTS

At baseline, 72.5 % had a low serum testosterone value (< 230 ng/dl), 67.56 % had low total sperm motility, 72.97% had low total progressive sperm motility, 80% had low ADAM score and 72.72% had low ASEX score. A raised prolactin level was seen in 32.5% of study subjects. Hypogonadotropic hypogonadism was more common than hypergonadotropic hypogonadism (89.66% vs. 10.34%). On restoration of euthyroidism, all these parameters improved. Serum INSL3 and LH increased significantly after thyroxine replacement, unlike FSH and INHB.

CONCLUSIONS

Leydig cell function seemed more severely affected by hypothyroidism as compared to Sertoli cell function. Among sperm function parameters, motility was predominantly affected.

The impact of thyroid diseases starting from birth on reproductive function

The aim of this review is to provide relevant information regarding the impact of thyroid disease, starting from birth and mainly concerning hyperthyroidism and hypothyroidism, on reproduction. Hyperthyroidism occurs much less commonly in children than hypothyroidism, with Graves' disease (GD) being the most common cause of thyrotoxicosis in children. Children born with neonatal GD have no defects in the reproductive system that could be related to hyperthyroidism. Current treatment options include antithyroid drugs (ATD), surgery, and radioactive iodine (RAI). In males, normal thyroid function seems important, at least in some parameters, for maintenance of semen quality via genomic or non-genomic mechanisms, either by locally acting on Sertoli cells, Leydig cells, or germ cells, or by affecting crosstalk between the HPT axis and the HPG axis. Sexual behavior may also be affected in thyroxic men, although many of these patients may have normal free testosterone levels. In women, menstrual irregularities are the most common reproduction-related symptoms in thyrotoxicosis, while this disorder is also associated with reduced fertility, although most women remain ovulatory. An increase in sex hormone-binding globulin (SHBG) and androgens, thyroid autoimmunity, and an impact on uterine oxidative stress are the main pathophysiological mechanisms which may influence female fertility. Thyroid hormones are responsible for normal growth and development during pre- and postnatal life, congenital hypothyroidism (CH) being the most common cause of neonatal thyroid disorders, affecting about one newborn infant in 3500. The reproductive tract appears to develop normally in cretins. Today, CH-screening programs allow for early identification and treatment, and, as a result, affected children now achieve normal or near-normal development. Hypothyroidism in males is associated with decreased libido or impotence. Although little is currently known about the effects of hypothyroidism on spermatogenesis and fertility, it has been established that sperm morphology and motility are mainly affected. In women of reproductive age, hypothyroidism results in changes in cycle length and amount of bleeding. Moreover, a negative effect on fertility and higher miscarriage rates has also been described.

The effect of vitamin D on thyroid autoimmunity in euthyroid men with autoimmune thyroiditis and testosterone deficiency

BACKGROUND

Autoimmune (Hashimoto's thyroiditis) is characterized by a strong female preponderance, which may suggest that sex hormones have an impact on thyroid autoimmunity. The aim of this study was to investigate whether testosterone determines vitamin D action on thyroid antibody titers and thyroid function tests in men with autoimmune thyroiditis and low testosterone levels.

METHODS

The study included 36 men with testosterone deficiency, 17 of whom had been treated for at least 26 weeks with oral testosterone undecanoate (120 mg daily). Because of coexistent euthyroid Hashimoto's thyroiditis, all participants were then treated with vitamin D (100 μg daily). Serum titers of thyroid peroxidase and thyroglobulin antibodies, serum levels of thyrotropin, free thyroid hormones, testosterone and 25-hydroxyvitamin D, as well as Jostel's thyrotropin index, SPINA-GT and SPINA-GD were assessed before vitamin D treatment and 26 weeks later.

RESULTS

With the exception of testosterone levels, there were no significant differences between both study groups in serum hormone levels, antibody titers and thyroid function tests. All participants completed the study. In addition to increasing 25-hydroxyvitamin D levels, vitamin D increased SPINA-GT and reduced thyroid peroxidase and thyroglobulin antibody titers. In testosterone-treated men, vitamin D increased testosterone levels. Vitamin D did not affect serum levels of thyrotropin, free thyroid hormones, Jostel's thyrotropin index and SPINA-GD. Treatment-induced changes in thyroid antibody titers and SPINA-GT were more pronounced in testosterone-treated than testosterone-naïve men.

CONCLUSIONS

The obtained results suggest that the beneficial effect on thyroid autoimmunity and thyroid secretory function is stronger in men receiving testosterone therapy.

The effect of spironolactone on thyroid autoimmunity in euthyroid men with Hashimoto's thyroiditis

WHAT IS KNOWN AND OBJECTIVE

Hashimoto's thyroiditis, also referred to as autoimmune thyroiditis, is characterized by sexual dimorphism, suggesting an important role of sex hormones in its development. No interventional study has investigated whether drugs exerting antiandrogen properties affect thyroid antibody titres and thyroid function tests in subjects with autoimmune thyroiditis.

METHODS

This study included 35 levothyroxine-naïve men with euthyroid Hashimoto's thyroiditis. At the physician's discretion, 18 men were then treated with spironolactone (50-200 mg daily), while the remaining patients (n = 17) received other diuretics. Serum levels of thyrotropin, free thyroid hormones, testosterone and 25-hydroxyvitamin D, as well as titres of thyroid peroxidase and thyroglobulin, were measured at the beginning of the study and 6 months later. Based on hormone levels, constant structure parameters of thyroid homeostasis were calculated.

RESULTS AND DISCUSSION

At baseline, there was no difference between the treatment arms in terms of thyroid antibody titres, hormone levels and the calculated parameters of thyroid homeostasis. Thirty-two patients completed the study. Spironolactone increased thyroid antibody titres, decreased testosterone and 25-hydroxyvitamin D levels and reduced SPINA-GT. The drug produced a neutral effect on serum levels of thyrotropin, free thyroid hormones, Jostel's thyrotropin index and SPINA-GD. The effect of spironolactone on antibody titres correlated with treatment-induced changes in SPINA-GT, testosterone and 25-hydroxyvitamin D. No significant changes in antibody titres, hormone levels and the calculated parameters of thyroid homeostasis were observed in spironolactone-naïve men.

WHAT IS NEW AND CONCLUSION

The obtained results indicate that spironolactone may exert an unfavourable effect on progression of autoimmune thyroiditis in men.

The effect of testosterone on thyroid autoimmunity in euthyroid men with Hashimoto's thyroiditis and low testosterone levels

WHAT IS KNOWN AND OBJECTIVE

Thyroid autoimmune diseases occur much more frequently in women than men. Unfortunately, no previous study has determined whether sex hormones produce any effect on thyroid antibody titres. The primary study aim was to assess whether exogenous testosterone affects thyroid autoimmunity in men with Hashimoto's thyroiditis and low testosterone levels.

METHODS

The study population consisted of 34 euthyroid men with autoimmune thyroiditis and testosterone deficiency. On the basis of patient preference, these patients were either treated with oral testosterone undecanoate (120 mg daily; n = 16) or remained untreated (n = 18). Circulating levels of thyrotropin, free thyroxine, free triiodothyronine, prolactin and total testosterone, as well as serum titres of thyroid peroxidase and thyroglobulin antibodies, were measured at the beginning of the study and 6 months later. The structure parameters of thyroid homeostasis (Jostel's thyrotropin index, SPINA-GT and SPINA-GD) were also calculated. Moreover, semen analyses were performed in eight patients in each group.

RESULTS AND DISCUSSION

In testosterone-naïve men, serum hormone levels and antibody titres remained at the similar levels throughout the study. Apart from increasing serum testosterone levels, testosterone undecanoate reduced titres of thyroid peroxidase and thyroglobulin antibodies and increased SPINA-GT. The drug produced a neutral effect on circulating levels of thyrotropin, free thyroid hormones, prolactin and testosterone, Jostel's thyrotropin index, SPINA-GD and semen parameters. Testosterone-induced changes in antibody titres correlated with the effect of treatment on SPINA-GT and with serum testosterone levels.

WHAT IS NEW AND CONCLUSION

This study is the first one to have shown that exogenous testosterone may have a protective effect on thyroid autoimmunity in men with Hashimoto's thyroiditis and testosterone deficiency.

Effect of Adequate Thyroid Hormone Replacement on the Hypothalamo-Pituitary-Gonadal Axis in Premenopausal Women with Primary Hypothyroidism

BACKGROUND

While the effects of thyroxine (T₄) replacement on improving gonadal function in hypothyroid men has been well documented, the same has not been adequately studied in hypothyroid premenopausal women.

METHODOLOGY

Premenopausal women with overt hypothyroidism (thyroid-stimulating hormone [TSH] > 15 IU/L) were tested in the early follicular phase of their natural menstrual cycles or after a progesterone challenge for gonadotropins, estradiol (E₂), and prolactin (PRL). They were then treated adequately with T₄ replacement and retested under similar circumstances for the same parameters ≥2 months after the restoration of euthyroidism.

RESULTS

Forty premenopausal hypothyroid women were evaluated at baseline and ≥2 months after adequate T₄ replacement. At baseline, there was an inverse correlation of the gonadotropins (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]) and TSH, prolactin (PRL) and free T₄ (fT₄), and E₂ and PRL. After normalization of the thyroid function, there was a significant fall in PRL (p < 0.001) accompanied by a rise in serum E₂ (p < 0.001). There were no changes in the levels of the gonadotropins LH and FSH. The proportion of patients with hyperprolactinemia fell 5-fold, from 5/40 to 1/40. While there were 5 patients with low estrogen prior to treatment, there were none with hypoestrogenemia after treatment.

CONCLUSION

Hypothyroidism is associated with a reversible partial suppression of the hypothalamo-pituitary-gonadal axis in premenopausal women, demonstrated by lower E₂ along with a mild elevation of PRL. Treatment of hypothyroidism improves the level of estrogen and lowers the level of PRL.

Impact of thyroid disease on testicular function

INTRODUCTION

Testis was considered unresponsive to thyroid hormone for a long time. However, like in animals, the presence of thyroid hormone receptors in different testicular cell types was demonstrated also in humans. Accordingly, thyrotoxicosis and hypothyroidism have remarkable effects on testicular function and more extensively on fertility.

REVIEW

Thyrotoxicosis and hypothyroidism are associated with changes affecting the endocrine, sexual, or reproductive functions. Particularly, compared with controls, hyperthyroid patients have higher serum SHBG and lower free and bioavailable testosterone concentrations, a higher rate of astheno-zoospermia, oligo-zoospermia, and terato-zoospermia, and a higher prevalence of sexual disturbances, such as premature ejaculation. In hypothyroid patients, hormonal changes are in the opposite direction compared with hyperthyroid patients. Thyroid hormone regulates a number of functions in the testis, such as proliferation and differentiations of non-germ cells, steroidogenesis, and sperm motility. Furthermore, thyroid hormone regulates testicular redox status. Consequently, thyroid hormone excess or deficiency can affect testicular function at different levels.

CONCLUSIONS

In view of the high prevalence of thyrotoxicosis and hypothyroidism, a considerable part of infertile patients may harbor overt or subclinical thyroid disease. Identification and management of thyrotoxicosis/hypothyroidism associated infertility needs the collaboration of andrologists, endocrinologists, gynecologists, and general practitioners.

Differential regulation of steroidogenic enzyme genes by TRα signaling in testicular Leydig cells

Thyroid hormone signaling has long been implicated in mammalian testicular function, affecting steroidogenesis in testicular Leydig cells. However, its molecular mechanism is not well understood. Here, we investigated the molecular action of thyroid hormone receptor-α (TRα) on mouse testicular steroidogenesis. TRα/thyroid hormone (T3) signaling differentially affected the expression of steroidogenic enzyme genes, mainly regulating their promoter activity. TRα directly regulated the promoter activity of the cytochrome P450 17α-hydroxylase/C17-20 lyase gene, elevating its expression in the presence of T3. TRα also indirectly regulated the expression of steroidogenic enzyme genes, such as steroidogenic acute regulatory protein and 3β-hydroxysteroid dehydrogenase, by modulating the transactivation of Nur77 on steroidogenic enzyme gene promoters through protein-protein interaction. TRα enhanced Nur77 transactivation by excluding histone deacetylases from Nur77 in the absence of T3, whereas liganded TRα inhibited Nur77 transactivation, likely due to interfering with the recruitment of coactivator such as the steroid receptor coactivator-1 to Nur77. Together, these findings suggest a role of TRα/T3 in testicular steroidogenesis and may provide molecular mechanisms for the differential regulation of steroidogenic enzyme genes by thyroid hormone.

The forkhead transcription factor, FOXP3: a critical role in male fertility in mice

Fertility is dependent on the hypothalamic-pituitary-gonadal axis. Each component of this axis is essential for normal reproductive function. Mice with a mutation in the forkhead transcription factor gene, Foxp3, exhibit autoimmunity and infertility. We have previously shown that Foxp3 mutant mice have significantly reduced expression of pituitary gonadotropins. To address the role of Foxp3 in gonadal function, we examined the gonadal phenotype of these mice. Foxp3 mutant mice have significantly reduced seminal vesicle and testis weights compared with Foxp3(+/Y) littermates. Spermatogenesis in Foxp3 mutant males is arrested prior to spermatid elongation. Activation of luteinizing hormone signaling in Foxp3 mutant mice by treatment with human chorionic gonadotropin significantly increases seminal vesicle and testis weights as well as testicular testosterone content and seminiferous tubule diameter. Interestingly, human chorionic gonadotropin treatments rescue spermatogenesis in Foxp3 mutant males, suggesting that their gonadal phenotype is due primarily to a loss of pituitary gonadotropin stimulation rather than an intrinsic gonadal defect.

Thyroid function and human reproductive health

Via its interaction in several pathways, normal thyroid function is important to maintain normal reproduction. In both genders, changes in SHBG and sex steroids are a consistent feature associated with hyper- and hypothyroidism and were already reported many years ago. Male reproduction is adversely affected by both thyrotoxicosis and hypothyroidism. Erectile abnormalities have been reported. Thyrotoxicosis induces abnormalities in sperm motility, whereas hypothyroidism is associated with abnormalities in sperm morphology; the latter normalize when euthyroidism is reached. In females, thyrotoxicosis and hypothyroidism can cause menstrual disturbances. Thyrotoxicosis is associated mainly with hypomenorrhea and polymenorrhea, whereas hypothyroidism is associated mainly with oligomenorrhea. Thyroid dysfunction has also been linked to reduced fertility. Controlled ovarian hyperstimulation leads to important increases in estradiol, which in turn may have an adverse effect on thyroid hormones and TSH. When autoimmune thyroid disease is present, the impact of controlled ovarian hyperstimulation may become more severe, depending on preexisting thyroid abnormalities. Autoimmune thyroid disease is present in 5-20% of unselected pregnant women. Isolated hypothyroxinemia has been described in approximately 2% of pregnancies, without serum TSH elevation and in the absence of thyroid autoantibodies. Overt hypothyroidism has been associated with increased rates of spontaneous abortion, premature delivery and/or low birth weight, fetal distress in labor, and perhaps gestation-induced hypertension and placental abruption. The links between such obstetrical complications and subclinical hypothyroidism are less evident. Thyrotoxicosis during pregnancy is due to Graves' disease and gestational transient thyrotoxicosis. All antithyroid drugs cross the placenta and may potentially affect fetal thyroid function.

Clinical implications of altered thyroid status in male testicular function

Thyroid hormones are involved in the development and maintenance of virtually all tissues. Although for many years the testis was thought to be a thyroid-hormone unresponsive organ, studies of the last decades have demonstrated that thyroid dysfunction is associated not only with abnormalities in morphology and function of testes, but also with decreased fertility and alterations of sexual activity in men. Nowadays, the participation of triiodothyronine (T3) in the control of Sertoli and Leydig cell proliferation, testicular maturation, and steroidogenesis is widely accepted, as well as the presence of thyroid hormone transporters and receptors in testicular cells throughout the development process and in adulthood. But even with data suggesting that T3 may act directly on these cells to bring about its effects, there is still controversy regarding the impact of thyroid diseases on human spermatogenesis and fertility, which can be in part due to the lack of well-controlled clinical studies. The current review aims at presenting an updated picture of recent clinical data about the role of thyroid hormones in male gonadal function.

Thyroid hormones and thyroxine-binding globulin in relation to liver function and serum testosterone in men with alcoholic cirrhosis

In 73 euthyroid male patients with histologically verified alcoholic cirrhosis, thyroid hormones, thyroxine-binding globulin (TBG) and testosterone concentrations (total, non-protein- and non-SHBG-bound) were studied in relation to each other and to the degree of liver dysfunction. Serum concentrations of triiodothyronine (T3) decreased significantly (p less than 0.05) and thyroid-stimulating hormone (TSH) increased with progressing liver dysfunction. Serum concentrations of tetraiodothyronine (T4), TBG and T4/TBG ratio did not correlate significantly with liver function. Serum T3 concentrations correlated significantly (Kendall Tau-beta = -0.33, p = 0.001) with total serum testosterone concentrations, while there was a negative correlation (Kendall Tau-beta = -0.20, p = 0.025) between testosterone and TSH values. No correlation was found between testosterone concentrations and serum levels of TBG. It is proposed that the association between T3 and TSH on one hand and testosterone concentrations on the other reflects a covariation of these variables with liver function. The TBG level was normal in most patients and was not correlated to testosterone concentrations.

Hypothyroidism has an adverse effect on human spermatogenesis: a prospective, controlled study

BACKGROUND

Abnormalities of spermatogenesis are associated with numerous diseases and aging. The objective of this study was to investigate the impact of hypothyroidism on human spermatogenesis and different sperm function tests.

METHODS

Twenty-five hypothyroid men and 15 normal individuals were investigated. Semen analysis, fructose and acid phosphatase measurements, teratozoospermia index (TZI), and acridine orange test were determined before and 6-9 months after the initiation of treatment with levothyroxine.

RESULTS

Morphology is the only sperm parameter that differs significantly between hypothyroid patients and controls (p < 0.0001). After treatment, morphology improved significantly (p < 0.001). Motility was also decreased before treatment in comparison with controls, and improved after treatment. However, the difference was not significant. TZI correlated with free thyroxine.

CONCLUSIONS

Hypothyroidism has an adverse effect on human spermatogenesis. Morphology is the only sperm parameter that is significantly affected. Motility may also be affected, but further studies regarding this are needed. Screening for thyroid dysfunction in males who present with a defect in spermatogenesis is strongly recommended, and if hypothyroidism is noted, the response to thyroid hormone should be evaluated before initiating other treatments.

Hormonal evaluation of the infertile male: has it evolved?

An endocrinologic evaluation of patients who have male-factor infertility has clearly evolved and leads to specific diagnoses and treatment strategies in a large population of infertile men. A well-considered endocrine evaluation is especially essential with the ever-growing popularity of assisted reproductive techniques and continued refinements with intracytoplasmic sperm injection.

Investigation on the Histopathological Effects of Thyroidectomy on the Seminiferous Tubules of Immature and Adult Rats

INTRODUCTION

This study aimed to investigate the histopathological effects of thyroidectomy on both immature and adult rat testes.

MATERIALS AND METHODS

Male albino Wistar rats, 4 weeks old and weighing between 45 and 55 g, were used for this study. The experimental groups were as follows: 2-week control group (group I); 2-week thyroidectomy group (group II); 4-week control group (group III); 4-week thyroidectomy group (group IV); 6-week control group (group V), and 6-week thyroidectomy group (group VI). The control groups included both sham-operated and untreated rats. In groups II, IV and VI, total thyroidectomy was performed under ether anesthesia in all rats at 4 weeks of age. The rats were killed in the 2nd, 4th and 6th weeks, respectively, following the thyroidectomy. The testes of each animal were evaluated histologically.

RESULTS

In group II, spermatogenesis progressed to meiosis but round spermatids were found to be decreased and pachytene spermatocytes were observed to be increased when compared to group I. Giant pachytene spermatocytes were seen. There were also many degenerated cells of intermediate origin in the seminiferous epithelium. In groups IV and VI, spermatogonia and primary spermatocytes were normal in appearance, but there was widespread degeneration of the other spermatogenic cells. In addition, some closed lumina covered by degenerated and dead cells were observed. In group II, the mean outer diameter, luminal diameter and area occupied by seminiferous epithelium decreased by 19.74, 32.18, and 28.12%, respectively. In group IV, these data decreased by 23.9, 16.52, and 48.5%, respectively, and in group VI, by 21.10, 19.76 and 40.29%, respectively, when compared with the control groups. These data were statistically significant (p < 0.001).

CONCLUSIONS

Thyroid hormones could have a marked influence on the seminiferous tubules of both immature and adult rats, and their permanent lack results in a depression in seminiferous tubule growth as shown by the reduced outer and luminal diameters and area occupied by the seminiferous epithelium, which could give rise to degenerative changes in the spermatogenic cells of thyroidectomized rats. In addition, all these changes could also result from both the inability of Sertoli cells to support spermatogenic cells and the diminished levels of GH and FSH.

Effect of hypothyroidism on the purinergic responses of corpus cavernosal smooth muscle in rabbits

AIMS

Several studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men. In the present study, we examined purinergic relaxation responses in hypothyroidism in an experimental rabbit model and compared them with controls to evaluate the possible involvement of the purinergic pathway.

MATERIALS AND METHODS

The study comprised 20 male New Zealand white rabbits. The rabbits were divided into two equal groups. We tested the effects of ATP, alpha beta ATP, and adenosine precontracted with phenylephrine on the isolated corpus cavernosum preparations from control and hypothyroid rabbits. We also evaluated the effects of ATP, alpha beta ATP, and adenosine on the cGMP levels in the isolated corpus cavernosum preparations from control and hypothyroid rabbits.

RESULTS

T3, T4, and testosterone levels were significantly lower in hypothyroid rabbits. ATP, alpha beta ATP, carbachol, and electrical field stimulation (EFS)-induced frequency-dependent relaxation responses in the isolated rabbit corpus cavernosum strips precontracted with phenylephrine reduced significantly (P<0.05). Adenosine-induced relaxation responses did not change significantly in hypothyroid rabbits.

CONCLUSION

Reduction of relaxation response in hypothyroid rabbits corpus cavernosum can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium.

Secretion of testicular steroids and gonadotrophins in hypothyroidism

Inconsistent alterations in gonadal steroidogenesis and pituitary functions have been reported in hypothyroid males. We have compared the lipid and endocrine profiles of the euthyroid and hypothyroid [thyroid-stimulating hormone (TSH) >100 mIU l(-1)] males. Hypothyroidism was found to be associated with an increase in the circulating level of total cholesterol and LDL-cholesterol (LDL-C) and a reduction in the levels of progesterone and testosterone, without any change in the serum levels of oestradiol and gonadotrophins. The failure of gonadotrophins to rise could be accounted by a normal level of serum oestradiol in the hypothyroid male. A mild hyperprolactinaemia was also noted in the hypothyroid patients. The reduction in serum testosterone level could be explained by (i) a reduced uptake of LDL-C by the Leydig cells and thereby a reduction in the synthesis of progesterone and consequentially testosterone, (ii) a further reduction in the rate of conversion of progesterone to testosterone, (iii) a higher rate of conversion of testosterone to oestradiol, (iv) a decrease in serum triiodothyronine and (v) hyperprolactinaemia. Rise in TSH needs to be investigated as a cause of the suppression of gonadal steroidogenesis.

Sexual dysfunction in men and women with endocrine disorders

Endocrine disease frequently interrupts sexual function, and sexual dysfunction may signal serious endocrine disease. Diabetic autonomic neuropathy and endothelial dysfunction impair erectile function, and phosphodiesterase inhibition produces only moderate benefit. The effect of diabetes on women's sexual function is complex: the most consistent finding is a correlation between sexual dysfunction and depression. Reductions in testosterone level in men are associated with low sexual desire and reduced nocturnal erections and ejaculate volume, all of which improve with testosterone supplementation. The age-dependent decline in testosterone production in men is not associated with precise sexual symptoms, and supplementation has not been shown to produce sexual benefit. In women, sexual dysfunction has not been associated with serum testosterone, but this may be confounded by limitations of assays at low concentrations and by the greater importance of intracellular production of testosterone in women than in men. Testosterone supplementation after menopause does improve some aspects of sexual function in women, but long-term outcome data are needed. More research on the sexual effects of abnormal adrenal and thyroid function, hyperprolactinaemia, and metabolic syndrome should also be prioritised. We have good data on local management of the genital consequences of oestrogen lack, but need to better understand the potential role of systemic oestrogen supplementation from menopause onwards in sexually symptomatic women.

Infertility and thyroid disorders

PURPOSE OF REVIEW

This review highlights the 'gap' in knowledge regarding the contribution of thyroid dysfunction in reproduction. Thyroid dysfunction, which is quite prevalent in the population affects many organs including the male and female gonads, interferes with human reproductive physiology, reduces the likelihood of pregnancy and adversely affects pregnancy outcome, thus becoming relevant in the algorithm of reproductive dysfunction.

RECENT FINDINGS

Although menstrual irregularities are common, ovulation and conception can still occur in hypothyroidism, where thyroxine treatment restores a normal menstrual pattern and reverses hormonal changes. Subclinical hypothyroidism may be associated with ovulatory dysfunction and adverse pregnancy outcome. Thyroid autoimmunity increases the miscarriage rate, and thyroxine treatment does not seem to protect. Menstrual disturbances, frequent in thyrotoxicosis are restored following treatment. In males, thyrotoxicosis has a significant but reversible effect on sperm motility. Although radioactive Iodine (I) in ablation doses may transiently affect the gonads, it does not decrease fertility or increase genetic malformation rate in the offspring.

SUMMARY

Awareness of the thyroid status in the infertile couple is crucial, because of its significant, frequent and often reversible or preventable effect on infertility. Many aspects of the role of thyroid disorders however in infertility need further research.

On association between cortical 5-HT2A receptors and behavior in rats with experimental thyroid disturbances

Thyroid hormones (TH) were hypothesized to affect behavior via neurotransmission alterations. The present study was aimed to reveal effects of chronic TH deficit and excess on some types of adaptive behavior (catalepsy, acoustic startle reflex, open-field performance), sexual arousal and cerebral 5-HT2A serotonin receptors of adult Wistar rats. Administration of thyroxine synthesis inhibitor, propylthiouracil (PTU, 50 mg/l, 28 days), in drinking water produced substantial decrease in plasma thyroxine level and body weight gain, attenuated significantly acoustic startle reflex amplitude, sexual motivation and plasma testosterone surge in response to receptive female introduction, increased predisposition to catalepsy without considerable effects on open-field performance. L-thyroxine treatment (T4, 0.5 mg/l, 28 days) caused significant plasma thyroxine augmentation, somatic growth retardation and disturbances in sexual but not in other types of behavior studied. TH dysfunctions markedly increased number of DOI-induced wet dog shakes reflecting high functional activity of 5-HT2A receptors without any effect on cortical 5-HT2A receptor mRNA level. The involvement of cerebral 5-HT2A receptors alterations at posttranslational level in mechanisms of TH effects on sexual arousal was suggested. The data attract particular attention to undesirable effects of PTU and L-thyroxine treatment on behavior.

ORIGINAL RESEARCH—PATHOPHYSIOLOGY: Clinical Biologic Pathophysiologies of Women's Sexual Dysfunction

INTRODUCTION

Data concerning the biologic pathophysiology of desire, arousal, and orgasm in women are limited.

AIM

To gain knowledge of biologic pathophysiology of female sexual function. METHODS. To provide state-of-the-art knowledge concerning female sexual dysfunction, representing the opinions of seven experts from five countries developed in a consensus process over a 2-year period.

MAIN OUTCOME MEASURE

An International Consultation in alliance with key urological and sexual medicine societies convened over 200 multidisciplinary specialists from 60 countries into 17 consultation committees. The aims, goals and intentions of each committee were defined. Expert opinion was based on grading of evidence-based medical literature, extensive internal committee dialogue, open presentation, and debate.

RESULTS

Three critical physiologic requirements, including intact sex steroids, autonomic/somatic nerves, and arterial inflow/perfusion pressure to women's genital organs play fundamental roles in maintaining women's sexual function. Despite this, there are nominal data supporting a direct pathophysiologic involvement of abnormal sex steroid values, and/or damage/injury to neurologic and/or blood flow integrity in women with problems in sexual desire, arousal, and/or orgasm. This summary details the available literature concerning hormonal, neurologic, and vascular organic pathophysiologies of women's sexual dysfunctions.

CONCLUSIONS

Additional research on clinical pathophysiologies in women's sexual dysfunction is needed. This chapter encompasses data presented at the 2nd International Consultation on Sexual Medicine in Paris, France, June 28-July 1, 2003.

Specific aspects of erectile dysfunction in endocrinology

Prominent diseases of the endocrine system, such as diabetes mellitus, hypogonadism, and hyperprolactinemia, may cause erectile dysfunction (ED). ED affects about 50% of male diabetic patients possibly due to the vascular and neuropathic complications. Metabolic control and selective phosphodiesterase type 5 inhibitors are therapies of choice for controlling ED. By correcting hypogonadism, testosterone levels are restored. This, and the use of dopaminergic drugs, which normalize prolactin levels in male hyperprolactinemia, may be effective in reversing ED in these endocrine disorders.

Studies on the functional relationship between thyroid, adrenal and gonadal hormones

In order to clarify the functional relationship between thyroid, adrenal and gonadal hormones, hypothyroidism was induced by administration of thiuoracil in adult male and female rats, and the effects of hypothyroidism on the adrenal and the gonadal axes were investigated in the present study. 1. The functional relationship between thyroid and adrenal hormones: Adrenal weights and corticosterone were lowered, whereas the secretion of ACTH, corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) increased in hypothyroid rats compared to euthyroid rats. These results indicate that hypothyroidism causes adrenal dysfunction directly and results in hypersecretion of CRH and AVP from the hypothalamus. 2. The functional relationship between thyroid and gonadal hormones: The pituitary response to LHRH was lowered, whereas the testicular response to hCG was not changed in hypothyroid rats. Hypothyroidism suppressed copulatory behavior in male rats. These results suggest that hypothyroidism probably causes dysfunction in gonadal axis at the hypothalamic-pituitary level in male rats. In adult female rats, hypothyroidism inhibited the follicular development accompanied estradiol secretion, whereas plasma concentrations of progesterone and prolactin (PRL) increased in hypothyroid female rats. Hypothyroidism significantly increased the pituitary content of vasoactive intestinal peptide (VIP) though it did not affect dopamine synthesis. These results suggest that hypothyroidism increases pituitary content of VIP and this increased level of VIP likely affects PRL secretion in a paracrine or autocrine manner. In female rats, inhibition of gonadal function in hypothyroid rats mediated by hyperprolactinemia in addition to hypersecretion of endogenous CRH.

Degenerate self-reactive human T-cell receptor causes spontaneous autoimmune disease in mice

Thyroid autoimmune disorders comprise more than 30% of all organ-specific autoimmune diseases and are characterized by autoantibodies and infiltrating T cells. The pathologic role of infiltrating T cells is not well defined. To address this issue, we generated transgenic mice expressing a human T-cell receptor derived from the thyroid-infiltrating T cell of a patient with thyroiditis and specific for a cryptic thyroid-peroxidase epitope. Here we show that mouse major histocompatibility complex molecules sustain selection and activation of the transgenic T cells, as coexpression of histocompatibility leukocyte antigen molecules was not needed. Furthermore, the transgenic T cells had an activated phenotype in vivo, and mice spontaneously developed destructive thyroiditis with histological, clinical and hormonal signs comparable with human autoimmune hypothyroidism. These results highlight the pathogenic role of human T cells specific for cryptic self epitopes. This new 'humanized' model will provide a unique tool to investigate how human pathogenic self-reactive T cells initiate autoimmune diseases and to determine how autoimmunity can be modulated in vivo.

Male reproductive function in relation with thyroid alterations

Despite the high prevalence of thyroid diseases in the general population, the impact of the latter on male reproductive function has been the subject of only a few well-controlled clinical studies. Hyperthyroidism appears to cause alterations in the sex steroid hormone metabolism as well as in spermatogenesis and fertility. Sperm motility is mainly affected. These abnormalities reverse after restoration of euthyroidism. The effects of hypothyroidism on male reproduction appear to be more subtle than those of hyperthyroidism and reversible. Severe juvenile hypothyroidism may be associated with precocious puberty. Hypothyroidism in adults is associated with disturbances in the sex steroid hormone metabolism as well as infertility, although available data concerning the latter are scarce. Radioiodine ((131)I) treatment for dfferentiated thyroid cancer may cause transient impairment of testicular function Gonadal damage may be cumulative in those requiring multiple administrations and sperm banking should be considered in such patients.

Thyroid hormone, glucocorticoids, and prolactin at the nexus of physiology, reproduction, and toxicology

A symposium at the 2003 Annual Meeting of the Society of Toxicology brought together an expert group of endocrinologists to review how non-reproductive hormones can affect the endocrine system. This publication captures the essence of those presentations. Paul Cooke and Denise Holsberger recapitulate the evidence of how thyroid hormones affect male and female reproduction, and reproductive development. Ray Witorsch summarizes the many effects of glucocorticoids on the reproductive system. Finally, Paul Sylvester reviews the mechanism of action of prolactin, and reminds us that this ancient hormone has many functions beyond lactation.

The interrelationships between thyroid dysfunction and hypogonadism in men and boys

Thyroid hormone deficiency affects all tissues of the body, including multiple endocrine changes that alter growth hormone, corticotrophin, glucocorticoids, and gonadal function. Primary hypothyroidism is associated with hypogonadotropic hypogonadism, which is reversible with thyroid hormone replacement therapy. In male children follicle-stimulating hormone (FSH) is elevated and associated with testicular enlargement without virilization. Men with primary hypothyroidism have subnormal responses of luteinizing hormone (LH) to gonadotropin-releasing hormone (GnRH) administration and normal response to human chorionic gonadotropin (hCG). Free testosterone concentrations are reduced in men with primary hypothyroidism and thyroid hormone replacement normalizes free testosterone concentrations. In men with primary hypothyroidism, prolactin is not consistently elevated (except in men and children with longstanding severe primary hypothyroidism), but prolactin declines following thyroid hormone replacement therapy. Thyroid hormone is known to affect sex hormone-binding hormonal globulin (SHBG) concentrations. Men with hyperthyroidism have elevated concentrations of testosterone and SHBG. Thyroid hormone therapy in normal men may also duplicate this elevation. In addition estradiol elevations are observed in men with hyperthyroidism, and gynecomastia is common in them as well. In contrast to patients with primary hypothyroidism, men with hyperthyroidism exhibit hyperresponsiveness of LH to GnRH administration and subnormal responses to hCG. Radioactive iodine therapy (RAI) of men treated for thyroid cancer produces a dose-dependent impairment of spermatogenesis and elevation of FSH up to approximately 2 years. Permanent testicular germ cell damage may occur in men treated with high doses of RAI. RAI commonly increases serum concentrations of FSH and LH while reducing inhibin B levels without affecting serum concentrations of testosterone. Thus, radioiodine therapy transiently impairs both germinal and Leydig cell function that usually recover by 18 months posttherapy.

Biochemical screening in the assessment of erectile dysfunction: what tests decide future therapy?

OBJECTIVES

To evaluate which biochemical tests, performed as screening tests in the assessment of erectile dysfunction (ED), lead to a change in standard treatment.

METHODS

We examined the results of the biochemical and endocrine tests performed as part of the assessment of 1455 men presenting with ED. We also documented the subsequent therapy.

RESULTS

We found abnormal findings in testosterone (5.7%), prolactin (0.5%), thyroid function tests (0.13%), liver function tests (12.8%), glucose (9.3%), cholesterol (15% in a subset of 531 men), and ferritin (1.6%). Hyperprolactinemia was not invariably associated with a suppressed testosterone level. Specific therapy with a dopamine agonist for hyperprolactinemia and with testosterone for hypogonadism was effective in treating ED. For the others, standard ED therapy was used.

CONCLUSIONS

The results of our study showed that screening tests fall into two categories. Testosterone and prolactin have a low yield but specific therapy is effective. Glucose and lipids have a higher yield but specific therapy is not immediately effective for ED. However, they, on their own merits, require management to prevent long-term morbidity and mortality.

Thyroid hormones: their role in testicular steroidogenesis

Thyroid hormones are important for growth and development of many tissues. Altered thyroid hormone status causes testicular abnormalities. For instance, juvenile hypothyroidism/neonatal transient hypothyroidism induces macroorchidism, increases testicular cell number (Sertoli, Leydig, and germ cells) and daily sperm production. Triiodothyronine (T3) receptors have been identified in sperm, developing germ cells, Sertoli, Leydig, and peritubular cells. T3 stimulates Sertoli cell lactate secretion as well as mRNA expression of inhibin-alpha, androgen receptor, IGF-I, and IGFBP-4. It also inhibits Sertoli cell mRNA expression of Müllerian inhibiting substance (MIS), aromatase, estradiol receptor, and androgen binding protein (ABP) and ABP secretion. T3 directly increases Leydig cell LH receptor numbers and mRNA levels of steroidogenic enzymes and steroidogenic acute regulatory protein. It stimulates basal and LH-induced secretion of progesterone, testosterone, and estradiol by Leydig cells. Steroidogenic factor-1 acts as a mediator for T3-induced Leydig cell steroidogenesis. Although the role of T3 on sperm, germ, and peritubular cells has not yet been completely studied, it is clear that T3 directly regulates Sertoli and Leydig cell functions. Further studies are required to elucidate the direct effect of T3 on sperm, germ, and peritubular cells.

Thyroid disease and male reproductive function

Despite the high prevalence of thyroid diseases in the general population, male reproductive function in patients with thyroid disease has been the subject of only a few studies. Hyperthyroidism appears to cause sperm abnormalities (mainly reduction in motility), which reverse after restoration of euthyroidism. Radioiodine therapy for hyperthyroidism or thyroid cancer may cause transient reductions in sperm count and motility, but there appears to be little risk of permanent effects provided that the cumulative dose is less than 14 MBq. The effects of hypothyroidism on male reproduction appear to be more subtle than those of hyperthyroidism and reversible. Severe, prolonged hypothyroidism in childhood may be associated with permanent abnormalities in gonadal function.

Characteristics of infertility and the improvement of fertility by thyroxine treatment in adult male hypothyroid rdw rats

We previously reported that rdw rats were infertile in both sexes. The present study was conducted to determine whether hypothyroidism in adult male rdw rats induced infertility by impairing sexual behavior or testicular function, whether the infertility could be reversed by thyroxine (T(4)) treatment, and whether the mutant could be produced by infertile rdw rats via in vitro fertilization. The sexual behavior was analyzed by pairing with normal female rats. The fertility of epididymal sperm was determined by in vitro fertilization. The results indicated that the infertility resulted from both defective sexual behavior and testicular function. No untreated rdw rats mated. The weights of epididymides were significantly low, whereas those of testes were not different from those of untreated normal rats. Epididymal sperm with cytoplasmic droplets were observed at a significantly high frequency. No fertilization was detected either in vivo or in vitro. Thyroxine treatment markedly increased serum T(4) levels and the weights of both epididymides and testes. Partial reversion of the impaired sexual behavior was observed, and the percentage of epididymal sperm with cytoplasmic droplets was markedly decreased after T(4) treatment. Fertility of epididymal sperm was completely reversed when determined both in vivo and in vitro, and homozygous embryos developed to term after transfer without loss of viability.

Testicular dysfunction in men with primary hypothyroidism; reversal of hypogonadotrophic hypogonadism with replacement thyroxine

OBJECTIVE

Primary hypothyroidism can cause disturbances in normal gonadal function. The aim of this study was to investigate the relationship in men between hypogonadism and primary hypothyroidism and the extent to which free and total testosterone levels rose after introduction of replacement thyroxine.

DESIGN

Paired study of patients in a hypothyroid and thyroxine treated state.

PATIENTS

Ten men with primary hypothyroidism.

MEASUREMENTS

Free and total testosterone, gonadotrophin and prolactin levels before and after thyroxine replacement therapy.

RESULTS

Low free testosterone levels (161 +/- 62 pmol/l) demonstrated at the time the men were hypothyroid rose significantly with the commencement of thyroxine replacement (315 +/- 141 pmol/l; P < 0.001). Gonadotrophin levels were not elevated consistent with hypogonadotrophic hypogonadism. Hyperprolactinaemia, which can occur in primary hypothyroidism and cause hypogonadotrophic hypogonadism, was not present in the majority of these patients. However a reduction in prolactin level was evident with thyroxine replacement and a rise in free testosterone levels.

CONCLUSION

This suggests an effect of hypothyroidism on gonadotrophin secretion at the level of the hypothalamus-pituitary, either directly or through modulation of prolactin secretion. Low free testosterone may also be a contributing factor to some of the symptoms and signs of hypothyroidism in men.

Reproductive effects of nontesticular illness

Diseases in other organs may impair the male reproductive system. Acute critical conditions such as severe trauma, surgery, myocardial infarction, burns, liver failure, intoxication, or starvation are associated with suppression of gonadotropin secretion and secondary hypogonadism. With chronic illnesses, a primary testicular disorder with elevated gonadotropin levels may occur. This may be associated with increased peripheral conversion of androgens to estrogens, resulting in clinical presentation of combined androgen deficiency and estrogen excess. The association of hypogonadism and feminization with cirrhosis of the liver is a classic example. Types of hypogonadism that may occur with chronic anemia, chronic renal failure, chronic spinal cord injury, thyroid diseases, Cushing's syndrome, diabetes mellitus, obesity, HIV infection, neoplasia, and other chronic illnesses are also described. Numerous drugs have side effects on the reproductive system.

Effects of thyroidectomy or thiouracil treatment on copulatory behavior in adult male rats

Male copulatory behavior and the function of the hypothalamo-hypophysial-gonadal axis in hypothyroid male rats were investigated in the present study. Hypothyroidism was induced by thyroidectomy or thiouracil. In male copulatory behavior test, intromission latencies in hypothyroid rats were significantly longer than those in euthyroid rats and ejaculation frequencies were reduced in hypothyroid male rats compared to control rats without reduction of plasma concentrations of testosterone. These changes in copulatory behavior in hypothyroid male rats were restored to control levels by administration of T4 (5 micrograms/rat). Hypothyroidism decreased adrenal weights, and basal and peak concentrations of corticosterone during diurnal variation, whereas it increased peak concentrations of ACTH in adult male rats. These results indicate that hypothyroidism causes adrenal dysfunction directly and results in hypersecretion of ACTH. The adrenal disturbance observed in hypothyroid rats may affect male copulatory behavior.

Effects of thyroid status on pituitary gonadotropin and testicular reserve in men

This investigation was conducted to evaluate the effect of thyroid dysfunction on the pituitary-gonadal axis. Ten men with Graves' disease and 5 hypothyroid patients were studied; 10 normal males were studied as a control group. In untreated conditions hyperthyroidism was associated with a normal serum-free testosterone concentration, an increased serum of 17OHP levels, a reduced testosterone response to hCG stimulation, and a hyperresponse of LH to GnRH. These abnormalities reverted after normalization of high FT4 serum levels. Untreated hypothyroid men showed a normal hormone sex response to hCG, but the LH responst to GnRH was reduced, with a tendency to improve after T4 supplementation. There was a strong and significant negative correlation between FT4 and testosterone response, expressed as an area under the curve, and a positive correlation with LH response to GnRH. Despite normal basal free testosterone concentrations, 70% of hyperthyroid and 60% of hypothyroid patients had complaints of decreased libido. The results suggest that thyroid hormones play an important dual pituitary-gonadal effect that is reflected by an impairment of testicular testosterone synthesis associated to hyperresponse to LH in hyperthyroidism and a defective LH response to GnRH in hypothyroidism.

Assessment and treatment of impotence

Impotence is a common problem. History is primarily relied on to diagnose psychogenic impotence. Sex therapy is an effective treatment. Antihypertensive and psychiatric medicines often cause impotence, but most medicines should be considered a cause if this is supported by the history. Hormonal causes should be suspected in a patient with decreased libido or decreased testicular size, and testosterone should be measured in these cases. Hormone replacement may restore sexual function in hypogonadal men. Doppler sonogram or arteriography should be used to diagnose vascular impotence for men who would be good surgical candidates. Only young men without other illness are considered. There is little need to test neurologic function because there is no specific treatment for neurogenic impotence. These patients and patients who do not respond to the aforementioned treatments should be offered the vacuum erection device, penile self-injection therapy, or penile prosthesis. Choice depends on comorbid illness as well as patient preference. A basic algorithm for the evaluation and treatment of impotence is given in Figure 2.

Influence of hypothyroidism induced at prepuberty on epididymal lipids and the number and motility of spermatozoa in rats

Fifteen prepubertal male rats (age 30 days) were divided into three groups of five each: Group 1, hypothyroid (Tx)--rats were thyroidectomized at day 30; Group 2, T4 (L-thyroxine) replacement therapy (Tx+T4)--rats were thyroidectomized at day 30 and treated daily i.m. with T4 (6 micrograms/100 g body weight/day) for 30 days from day 31 to day 60 post-thyroidectomy (age 90 days); Group 3, control--rats were sham-operated and treated with vehicle. The rats from all groups were killed on day 61 post-thyroidectomy or post-sham operation (age 91 days). The serum levels of testosterone, T4 and T3 decreased in the Tx group (p < 0.001). In the Tx+T4 group the levels of T4 and T3 were restored to control values, whereas testosterone levels remained lower than in the control group. Hypothyroidism caused various changes in the levels of epididymal phospholipids and neutral lipids. These were restored differentially or were altered further in the Tx+T4 group. The number and forward motility of spermatozoa, recovered from the cauda epididymis, were decreased significantly (p < 0.01) in the Tx group and were not restored in the Tx+T4 group. This study shows that chronic hypothyroidism, induced at prepuberty and continued for 60 days, causes various changes in the lipid composition of the caput and cauda epididymis and lowers the quality and quantity of spermatozoa in the cauda epididymis. T4 therapy for 30 days, especially during the postpubertal period, did not restore the quality or quantity of spermatozoa and caused differential changes in the levels of epididymal lipids, depending upon the region.(ABSTRACT TRUNCATED AT 250 WORDS)

Macroorchidism and testicular fibrosis associated with autoimmune thyroiditis

A 16-year-old male with long-standing atrophic chronic lymphocytic thyroiditis was evaluated for macroorchidism. A testicular biopsy prior to treatment revealed peritubular and interstitial fibrosis, reduced spermatogenesis and sparse Leydig cells with nonprominent smooth endoplasmic reticulum. Biological/immunological LH and FSH ratios were reduced, I-LH and FSH response to GnRH was blunted, and levels of testosterone and androstenedione were low. Twenty-two months after thyroid treatment, the testicular size was unchanged, and the degree of fibrosis showed minimal regression. Spermatogenesis with normal morphology was present, Leydig cells with Reinke crystals were present, and surface area and diameter of the seminiferous tubules had increased only slightly. There was a normal I-LH and FSH response to GnRH, and normal levels of testosterone and androstenedione. This study, along with previous reports, suggests that the etiology of the hypothyroid state may influence the development of testicular fibrosis.