A simple radioimmunoassay for plasma testosterone plus 5alpha-dihydrotestosterone

New Biomarkers to Evaluate Hyperandrogenemic Women and Hypogonadal Men

Androgens can have variable effects on men and women. Women may be evaluated for androgen excess for several reasons. Typically, young premenopausal women present with clinical symptoms of hirsutism, alopecia, irregular menses, and/or infertility. The most common cause of these symptoms is polycystic ovary syndrome. After menopause, even though ovaries stop producing estrogen, they continue to produce androgen, and women can have new onset of hirsutism and alopecia. Laboratory evaluation involves measurement of the major ovarian and adrenal androgens. In women, age, phase of the menstrual cycle, menopausal status, obesity, metabolic health, and sex hormone-binding proteins significantly affect total-androgen levels and complicate interpretation. This review will summarize the clinically relevant evaluation of hyperandrogenemia at different life stages in women and highlight pitfalls associated with interpretation of commonly used hormone measurements. Hypogonadism in men is a clinical syndrome characterized by low testosterone and/or low sperm count. Symptoms of hypogonadism include decreased libido, erectile dysfunction, decreased vitality, decreased muscle mass, increased adiposity, depressed mood, osteopenia, and osteoporosis. Hypogonadism is a common disorder in aging men. Hypogonadism is observed rarely in young boys and adolescent men. Based on the defects in testes, hypothalamus, and/or pituitary glands, hypogonadism can be broadly classified as primary, secondary, and mixed hypogonadism. Diagnosis of hypogonadism in men is based on symptoms and laboratory measurement. Biomarkers in use/development for hypogonadism are classified as hormonal, Leydig and Sertoli cell function, semen, genetic/RNA, metabolic, microbiome, and muscle mass-related. These biomarkers are useful for diagnosis of hypogonadism, determination of the type of hypogonadism, identification of the underlying causes, and therapeutic assessment. Measurement of serum testosterone is usually the most important single diagnostic test for male hypogonadism. Patients with primary hypogonadism have low testosterone and increased luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Patients with secondary hypogonadism have low testosterone and low or inappropriately normal LH and FSH. This review provides an overview of hypogonadism in men and a detailed discussion of biomarkers currently in use and in development for diagnosis thereof.

Hypogonadism in the aging male diagnosis, potential benefits, and risks of testosterone replacement therapy

Hypogonadism in older men is a syndrome characterized by low serum testosterone levels and clinical symptoms often seen in hypogonadal men of younger age. These symptoms include decreased libido, erectile dysfunction, decreased vitality, decreased muscle mass, increased adiposity, depressed mood, osteopenia, and osteoporosis. Hypogonadism is a common disorder in aging men with a significant percentage of men over 60 years of age having serum testosterone levels below the lower limits of young male adults. There are a variety of testosterone formulations available for treatment of hypogonadism. Data from many small studies indicate that testosterone therapy offers several potential benefits to older hypogonadal men. A large multicenter NIH supported double blind, placebo controlled study is ongoing, and this study should greatly enhance the information available on efficacy and side effects of treatment. While safety data is available across many age groups, there are still unresolved concerns associated with testosterone therapy. We have reviewed the diagnostic methods as well as benefits and risks of testosterone replacement therapy for hypogonadism in aging men.

Crystalloid formation in Leydig cells of rats (Rattus fuscipes). An ultrastructural and hormonal study

The ultrastructure of Leydig cells in a seasonally breeding rodent, Rattus fuscipes, was studied in the breeding and non-breeding season and compared with Leydig cell morphology after suppression of gonadotrophin secretion induced by hypophysectomy or chronic administration of testosterone. Serum luteinizing hormone (LH) and testosterone (T) were measured and in-vitro T production by testes was assessed by stimulation with human chorionic gonadotrophin (hCG). In non-breeding wild-trapped rats and rats with experimental suppression of gonadotrophins, the Leydig cells were atrophied and exhibited variable amounts of cytoplasmic lipid and crystalloid inclusions, the latter commonly dominating the cytoplasmic area. Compared with fertile rats, serum LH and hCG-stimulated T production of experimentally regressed rats was significantly reduced, confirming structural features indicative of Leydig cell inactivity. Atrophy of Leydig cell nuclei was accompanied by the formation of unusual intranuclear vesicles sometimes containing small crystalloids. Ultrastructural analysis suggested transfer of the vesicles to the cytoplasm where their unification gave rise to much larger crystalloid bodies. Crystalloids occurred when serum LH was depressed and with either full (T treatment) or arrested spermatogenesis (hypophysectomy) suggesting that their formation is governed by pituitary function and is not dependent upon the degree of spermatogenic activity.

Bromocriptine and the hypothalamic hypophyseal function in patients with chronic renal failure on chronic hemodialysis

Ten patients with chronic renal failure on chronic hemodialysis had the following tests to evaluate the integrity of the hypothalamic hypophyseal axis: (A) glucose tolerance test, (B) thyrotropin releasing hormone stimulation test, (C) clonidine stimulation test, (D) insulin induced hypoglycemia, and (E) LH/RH stimulation test. The majority of those tests were abnormal and prolactin values were found to be moderately elevated in all the patients. Bromocriptine (1.25 mg twice a day) was given to all the patients for 1 month and then, while on bromocriptine, the tests were repeated. Although there is a decrement in the concentration of serum prolactin level, none of the hypothalamic hypophyseal abnormalities were corrected. However, five of the ten patients reported an improvement of their impotence with bromocriptine. The patients who responded had high levels of FSH and LH with levels of testosterone above 1 mg/mL. The nonresponders had low FSH and LH levels and very low testosterone levels. Therefore, bromocriptine, although possibly beneficial in some dialysis patients, is not a drug that can normalize abnormal functioning of hormones in the dialysis population.

Effect of combination chemotherapy on pituitary-gonadal function in patients with lymphoma and leukemia

After at least four courses of intermittent chemotherapy, 14 of the 15 men with malignant lymphoma had elevated serum follicle-stimulating hormone (FSH). In three of these subjects, serial studies showed progressive increases in basal FSH and exaggerated FSH responses to luteinizing hormone releasing hormone (LHRH). Although gonadal biopsies were not done, this elevation of FSH is indicative of progressive and severe damage to the germinal epithelium by chemotherapy. Elevated leutinizing hormone (LH) was found in seven and decreased testosterone (T) in two of these subjects. Increased LH responses to LHRH stimulation were also found in the three subjects studied. These findings suggest that the testicular damage is not restricted to the germinal tissue. In four male subjects with acute myeloid leukemia treated by intermittent chemotherapy not containing any alkylating agents, FSH, LH, and T levels were normal. Three of the 4 female patients with malignant lymphoma and two with acute myeloid leukemia had normal basal, serial, and LHRH-stimulated FSH, LH, and estradiol (E2) levels. Elevated gonadotropins and low E2 were found only in subjects who had received abdominal irradiation.

Enzyme immunoassay of testosterone in plasma, with use of polyethylene glycol to separate antibody-bound and free hormone

We describe an enzyme immunoassay for testosterone in which we use a testosterone-3-(carboxymethyl)oxime horseradish peroxidase conjugate as the label and an antiserum, raised in rabbits, to testosterone-3-(carboxymethyl)oxime-bovine serum albumin conjugate. Polyethylene glycol (Carbowax 6000) is used to separate antibody-bound and free steroid. The assay has a sensitivity of 12 pg/assay tube and satisfies the usual criteria of specificity, precision and accuracy. The results agree well with those obtained with a comparable radioimmunoassay.

Evidence for Leydig cell dysfunction in rats with seminiferous tubule damage

To study the effects of seminiferous tubule damage on Leydig cell function and morphology, rats were treated by fetal irradiation (to induce Sertoli cell-only syndrome, SCO), 3 months administration of hydroxyurea (HU), or chronic feeding of a vitamin A-deficient diet (VAD). Leydig cell function was assessed by the measurement of serum LH and testosterone and the response of serum testosterone to hCG stimulation, while morphology was studied by electron microscopy after perfusion fixation. Serum LH was significantly elevated in each experimental group, while basal serum testosterone was significantly lower only in SCO rats. In all treatment groups, the serum testosterone response to hCG was significantly decreased when measureed as the area under the response curve. Despite a decreased response to hCG, the Leydig cells were larger than normal and showed striking increases in quantities of smooth endoplasmic reticulum, mitochondria and Golgi complex. Leydig cell dysfunction has been demonstrated in animals with varying degrees of seminiferous tubule damage, but paradoxically the cytological features of the Leydig cells were indicative of hypertrophy.

The effect of heroin addiction on pituitary-testicular function

The effect of heroin addiction on pituitary-testicular function was studied in 54 active and 19 abstinent addicts and their results were compared with those of 43 age-matched controls. Abnormal sexual function was frequently found in heroin addicts and this persisted after drug withdrawal. The mean total (mean +/- SE, 18.1 +/- 1.0 nmol/1) and free (0.17 +/- 0.03 nmol/1) testosterone (T) levels in heroin addicts were significantly lower than those in healthy controls (total T 22.8 +/- 1.1 nmol/1), P less than 0.005; free T 0.30 +/- 0.03 nmol/1, P less than 0.005). The mean sex hormone binding globulin binding capacity was higher in heroin addicts (60.1 +/- 5.2 mM) than in healthy controls (35.5 +/- 2.1 mM). These hormonal changes returned promptly to normal after withdrawal. The basal LH and FSH and the responses to LHRH were comparable in the three groups studied. The finding of significantly lower total and free T together with higher SHBG indicates an abnormal testicular function in heroin addiction. Normal basal and LHRH-stimulated LH and FSH levels suggest that chronic heroin abuse depressed testicular function via the hypothalamus or higher centres.

Effect of acute myocardial infarction on pituitary-testicular function

The effect of acute myocardial infarction on the secretions of LH, FSH and testosterone was studied in thirteen male patients. Plasma testosterone fell transiently on the fourth day after acute myocardial infarction. This was accompanied by a rise in LH on the same day which persisted for a week after infarction. Serum FSH showed no significant change. The data suggest that following the medical stress of myocardial infarction, testosterone concentration was suppressed resulting in a compensatory rise in LH.

Effect of surgical stress on pituitary-testicular function

The effect of surgical stress on the secretions of LH, FSH, testosterone (T) and oestradiol (E2) were studied in twelve male patients. During surgery LH rose significantly; post-operatively, LH fell but remained persistently elevated a week after operation. However, T and E2 fell progressively to a nadir on the second and fifth post-operative day respectively and remained suppressed. Serum FSH showed no significant change. Despite a post-operative decrease in sex hormone binding globulin (SHBG) binding capacity, non-SHBG bound T showed a decrease parallel to T. Multiple sampling studies showed that the secretions of LH were increased and that of T were decreased post-operatively. Following surgery, LH responses to LHRH were magnified, FSH and T responses showed no significant change when compared with the pre-operative responses. These data suggest that secretions of LH were increased during surgery. Following surgical stress, T and E2 concentrations were suppressed resulting in a compensatory elevation of LH concentrations.

Concentrations of circulating steroids in normal prepubertal and adult male and female humans, chimpanzees, rhesus monkeys, rats, mice, and hamsters: a literature survey

Radioimmunoassay (RIA) data on concentrations of circulating steroids in normal prepubertal and adult male and female humans, chimpanzees, rhesus monkeys, rats, mice, and hamsters have been collated from the literature. Few reports include data for both sexes, for age groups, or for more than one species. In selecting references for inclusion in the tables, efforts were made to choose data only from RIA procedures that were adequately validated. A number of similarities can be found by reviewing the tables. Levels of estradiol appear somewhat similar for humans, chimpanzees, and rhesus monkeys of both sexes. Among the notable differences are the levels of estradiol and progesterone in primates and rodents, the apparently high level of aldosterone in mice, and the patterns of progesterone secretion in mice and rats. All values in the tables have been converted to picograms for easy comparison between steroids and species. Data for humans are fairly complete, but there is a significant lack of information for several other species.

Clinical features and plasma hormone levels after surgical menopause

This study reports the plasma levels of follicle stimulating hormone, luteinising hormone, oestradiol and testosterone in 43 women who had undergone bilateral oöphorectomy. Age was the only variable of those investigated which appeared to influence a hormone level; testosterone levels were found to decrease with increasing age. Two significant associations were found between clinical features of the menopause and the plasma hormone levels measured. Low levels of oestradiol were associated with pruritus vulvae and high levels of testerone were associated with headaches.

Hypertension due to 17alpha-hydroxylase deficiency

A female patient with hypertension, hypogonadism and hypokalaemia due to 17alpha-hydroxylase deficiency is described, in whom the diagnosis was initially based on the finding of low urinary 17-ketosteroids and 17-hydroxycorticosteroids, in the presence of high plasma fluorometric 11-hydroxycorticoids. Later studies confirmed the diagnosis by demonstrating low circulating levels of 17alpha-hydroxyprogesterone and the steroids derived from this precursor: 11-deoxycortisol, cortisol, oestradiol and testosterone. Plasma progesterone, corticosterone and deoxycorticosterone (DOC) were greatly increased, but plasma and urine aldosterone were very low. The initial subnormal cortisol and 11-deoxycortisol levels responded to tetracosactrin administration, suggesting that the adrenal was not maximally stimulated by endogenous ACTH and indicating that the 17alpha-hydroxylase deficiency was incomplete. Plasma and urinary aldosterone levels were still suppressed after 12 months treatment with prednisone despite normalization of the previously suppressed renin levels. The findings indicate that this uncommon cause of medically-controllable juvenile hypertension can be identified without specific steroid assays.

The pituitary-testicular axis in men with chronic renal failure

We studied the effects of uremia on the pituitary-testicular axis in 35 men with creatinine clearances less than 4 ml per minute per 1.7m(2). We found significant elevation (p less than 0.001) of plasma luteinizing hormone and follicle-stimulating hormone (p less than 0.005) and subnormal levels of testosterone (p less than 0.005). Testicular histology revealed severe spermatogenic damage. Human chorionic gonadotropin produced a subnormal testosterone response. The initial response of plasma luteinizing hormone and follicle-stimulating hormone to luteinizing-hormone-releasing hormone was normal, but their subsequent decline was prolonged. The suppression of plasma luteinizing hormone levels by testosterone propionate was normal, but the nadir occurred late; the elevated plasma luteinizing hormone level was due to reduced metabolic clearnace and increased production. Chronic renal failure interferes with testicular steroid production and spermatogenesis.

Changes in the pituitary-testicular system with age

In order to provide a comprehensive account of pituitary-testicular function in man, 466 subjects, ranging in age from 2 to 101 years, were studied to examine blood levels of the pituitary gonadotrophins (LH and FSH), the sex steroids testosterone and oestradiol, the binding capacity of the sex hormone binding globulin (SHBG), the free testosterone and oestradiol fractions, and the transfer constant for the peripheral conversion of testosterone to oestradiol. The results were compared with clinical indices of testicular size, sexual function and secondary sex hair distribution. Serum LH and FSH were low before puberty, increased in pubertal adolescents to levels somewhat above those of adults and subsequently increased progressively over the age of 40 years. Testosterone levels fell slowly after the age of 40, while there was a slight rise in plasma oestradiol with increasing age. FSH and testosterone showed small seasonal variations in young adult men, the lowest values being seen in winter. SHBG binding capacity was high in two prepubertal boys, fell in adult men, but increased in old age. Free testosterone and oestradiol levels fell in old age. The metabolic clearance rates (MCR) of testosterone and oestradiol also fell in old age, while the conversion of testosterone to oestradiol was increased. Many correlations were observed between various hormonal and clincial measurements. The evidence is consistent with a primary decrease in testicular function over the age of 40 years.

Hormonal studies in Klinefelter's syndrome

Some aspects of the hormonal abnormalities of Klinefelter's syndrome have been studied in nineteen patients. As a group the plasma production rate, the total and free levels of testosterone, and the metabolic clearance rates of testosterone and oestradiol were low. Plasma oestradiol, LH and FSH levels were elevated and there was increased peripheral conversion of testosterone to oestradiol. The production rates of oestradiol and the binding capacities of the sex steroid binding globulin were normal. There were fluctuations in the blood levels of LH, FSH, testosterone and oestradiol, but these appeared to be less marked than in healthy men. Both LH and FSH levels were suppressed by acute or prolonged testosterone administration and there was no evidence for a differential effect on LH. It is suggested that the threshold for suppression of LH and FSH is increased in hypergonadotrophic states. Although no statistically significant relationships were found between the hormonal and clinical abnormalities of the syndrome it is probable that the hyperoestrogenism and androgen deficiency are linked to the development of the signs of feminization and hypogonadism.