(See also Male Hypogonadism in Children Male Hypogonadism in Children Male hypogonadism is decreased production of testosterone, sperm, or both or, rarely, decreased response to testosterone, resulting in delayed puberty, infertility, or both. Diagnosis is by... read more .)
Etiology of Male Hypogonadism
Primary hypogonadism involves failure of the testes to respond to follicle-stimulating hormone (FSH) and luteinizing hormone (LH). When primary hypogonadism affects testosterone production, testosterone is insufficient to inhibit production of FSH and LH; hence, FSH and LH levels are elevated. The most common genetic cause of primary hypogonadism is Klinefelter syndrome Klinefelter Syndrome (47,XXY) Klinefelter syndrome is the presence of two or more X chromosomes plus one Y, resulting in a phenotypic male. Diagnosis is based on clinical findings and is confirmed by cytogenetic analysis... read more . It involves seminiferous tubule dysgenesis, failure of spermatogenesis, Leydig cell hyperplasia, and a 47,XXY karyotype.
Secondary hypogonadism is failure of the hypothalamus to produce gonadotropin-releasing hormone (GnRH), as in idiopathic hypogonadotropic hypogonadism, or of the pituitary gland to produce enough FSH and LH. In secondary hypogonadism, testosterone levels are low and levels of FSH and LH are low or borderline normal. Any acute systemic illness can cause temporary secondary hypogonadism. Some syndromes of hypogonadism have both primary and secondary causes (mixed hypogonadism). The table lists some common causes of hypogonadism by category.
Some syndromes of hypogonadism (eg, cryptorchidism, some systemic disorders) affect spermatozoon production more than testosterone levels.
Symptoms and Signs of Male Hypogonadism
Age at onset of testosterone deficiency (congenital, childhood-onset, or adult-onset hypogonadism) dictates the clinical presentation.
Congenital hypogonadism may be of 1st-, 2nd-, or 3rd-trimester onset. Congenital hypogonadism of 1st-trimester onset results in inadequate male sexual differentiation. Complete absence of testosterone’s effects results in normal-appearing female external genitals. Partial testosterone deficiency results in abnormalities ranging from ambiguous external genitals to hypospadias Hypospadias Congenital anomalies of the urethra in boys usually involve anatomic abnormalities of the penis and vice versa. In girls, urethral anomalies may exist without other external genital abnormalities... read more . Second- or 3rd-trimester onset of testosterone deficiency results in microphallus and undescended testes Cryptorchidism Cryptorchidism is failure of one or both testes to descend into the scrotum; in younger children, it is typically accompanied by inguinal hernia. Diagnosis is by testicular examination, sometimes... read more .
Childhood-onset testosterone deficiency (see Male Hypogonadism in Children Male Hypogonadism in Children Male hypogonadism is decreased production of testosterone, sperm, or both or, rarely, decreased response to testosterone, resulting in delayed puberty, infertility, or both. Diagnosis is by... read more ) has few consequences and usually is unrecognized until puberty is delayed. Untreated hypogonadism impairs development of secondary sexual characteristics. As adults, affected patients have poor muscle development, a high-pitched voice, a small scrotum, decreased phallic and testicular growth, sparse pubic and axillary hair, and an absence of body hair. They may develop gynecomastia and eunuchoidal body proportions (arm span > height by 5 cm and pubic to floor length > crown to pubic length by > 5 cm) because of delayed fusion of the epiphyses and continued long bone growth.
Adult-onset testosterone deficiency has varied manifestations depending on the degree and duration of the deficiency. Decreased libido; erectile dysfunction Erectile Dysfunction Erectile dysfunction is the inability to attain or sustain an erection satisfactory for sexual intercourse. Most erectile dysfunction is related to vascular, neurologic, psychologic, and hormonal... read more ; decline in cognitive skills, such as visual-spatial interpretation; sleep disturbances; vasomotor instability (in acute, severe male hypogonadism); and mood changes, such as depression and anger, are common. Decreased lean body mass, increased visceral fat, testicular atrophy, osteopenia, gynecomastia, and sparse body hair typically take months to years to develop. Testosterone deficiency may increase the risk of coronary artery disease Overview of Coronary Artery Disease Coronary artery disease (CAD) involves impairment of blood flow through the coronary arteries, most commonly by atheromas. Clinical presentations include silent ischemia, angina pectoris, acute... read more and prostate cancer. Prostate Cancer Prostate cancer is usually adenocarcinoma. Symptoms are typically absent until tumor growth causes hematuria and/or obstruction with pain. Diagnosis is suggested by digital rectal examination... read more
Diagnosis of Male Hypogonadism
Testing, beginning with follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone levels
Congenital and childhood-onset hypogonadism are often suspected because of developmental abnormalities or delayed puberty. Adult-onset hypogonadism should be suspected on the basis of symptoms or signs but is easily missed because these clinical markers are insensitive and nonspecific. Klinefelter syndrome Klinefelter Syndrome (47,XXY) Klinefelter syndrome is the presence of two or more X chromosomes plus one Y, resulting in a phenotypic male. Diagnosis is based on clinical findings and is confirmed by cytogenetic analysis... read more should be considered in adolescent males in whom puberty is delayed, young men with hypogonadism, and all adult men with very small testes. Hypogonadism requires confirmatory testing (see figure Laboratory Evaluation of Male Hypogonadism ).
Diagnosis of primary and secondary hypogonadism
Increases in FSH and LH are more sensitive for primary hypogonadism than are decreases in testosterone levels. Levels of FSH and LH also help determine whether hypogonadism is primary or secondary. High gonadotropin levels, even with low-normal testosterone levels, indicate primary hypogonadism, whereas gonadotropin levels that are low or lower than expected for the level of testosterone indicate secondary hypogonadism. Alternatively, in boys of short stature with delayed puberty, low testosterone plus low gonadotropin levels might result from constitutional delay of puberty. Elevation of serum FSH with normal levels of serum testosterone and LH often occurs when spermatogenesis is impaired but testosterone production is normal. The cause of hypogonadism is often evident clinically. Primary hypogonadism requires no further testing, although some clinicians do a karyotype to definitively diagnose Klinefelter syndrome Klinefelter Syndrome (47,XXY) Klinefelter syndrome is the presence of two or more X chromosomes plus one Y, resulting in a phenotypic male. Diagnosis is based on clinical findings and is confirmed by cytogenetic analysis... read more .
Total (and, when possible, free) serum testosterone, serum FSH, and serum LH levels are measured simultaneously. The normal range for total testosterone is 300 to 1000 ng/dL (10.5 to 35 nmol/L). The testosterone level should be drawn in the morning (before 10:00 AM) to confirm hypogonadism. Because of the increase in sex hormone–binding globulin (SHBG) with aging, total testosterone level is a less sensitive indicator of hypogonadism after age 50. Although serum free testosterone more accurately reflects functional testosterone levels, its measurement requires equilibrium dialysis, which is technically difficult and not widely available.
Some commercially available kits, including the analog free testosterone assay, attempt to measure serum free testosterone levels, but the results are often inaccurate, particularly in conditions (such as type 2 diabetes, obesity, and hypothyroidism) that alter SHBG levels. Free testosterone levels can be calculated based on SHBG, albumin, and testosterone values; there are calculators available online. See the Free and Bioavailable Testosterone Calculator.
Because of the pulsatile secretion of FSH and LH, these hormones are have been measured as a pooled sample of 3 venipunctures taken at 20-minute intervals, but these pooled samples seldom add clinically important information compared with a single blood sample. Serum FSH and LH levels are usually ≤ 5 mIU/mL (5 IU/L) before puberty and between 5 and 15 mIU/mL (5 and 15 IU/L) in adulthood.
Semen analysis should be done in all men who are seeking fertility treatment. In adolescents or adults, a semen sample collected by masturbation after 2 days of abstinence from ejaculation provides an excellent index of seminiferous tubular function. A normal semen sample (World Health Organization [WHO] standards) has a volume of > 1.5 mL with > 15 million sperm/mL, of which 50% are of normal morphology and are motile (see also Sperm Disorders Sperm Disorders Sperm disorders include defects in quality or quantity of sperm produced and defects in sperm emission. Diagnosis is by semen analysis and genetic testing. The most effective treatment is usually... read more ).
Laboratory evaluation of male hypogonadism
* Total testosterone has lower sensitivity for hypogonadism in men aged > 50 years. If the test for free and weakly bound testosterone is available, levels are measured. If not, levels are calculated.
† Recommended by some physicians.
CT = computed tomography; Fe = iron; FSH = follicle-stimulating hormone; GnRH = gonadotropin-releasing hormone; LH = luteinizing hormone; MRI = magnetic resonance imaging.
Evaluation of secondary hypogonadism
Because any systemic illness can temporarily decrease levels of testosterone, FSH, and LH, secondary hypogonadism should be confirmed by measuring these levels again at least 4 weeks after resolution of the systemic illness. To confirm secondary hypogonadism in adolescents, the GnRH stimulation test may be considered. If levels of FSH and LH increase in response to IV GnRH, puberty is simply delayed. If levels do not increase, true hypogonadism is likely.
To help determine the cause of confirmed secondary hypogonadism, testing should include serum prolactin level (to screen for pituitary adenoma) and transferrin saturation (to screen for hemochromatosis Hereditary Hemochromatosis Hereditary hemochromatosis is a genetic disorder characterized by excessive iron (Fe) accumulation that results in tissue damage. Manifestations can include systemic symptoms, liver disorders... read more ). Sella imaging with MRI or CT is done to exclude a pituitary macroadenoma or other mass in men with any of the following:
Age < 60 years with no other identified cause for hypogonadism
Very low total testosterone levels (< 200 ng/dL [6.94 nmol/L])
Elevated prolactin levels
Symptoms consistent with a pituitary tumor (eg, headache, visual symptoms)
Also, if there are symptoms or signs of Cushing syndrome Cushing Syndrome Cushing syndrome is a constellation of clinical abnormalities caused by chronic high blood levels of cortisol or related corticosteroids. Cushing disease is Cushing syndrome that results from... read more , 24-hour urine collection for free cortisol or a dexamethasone suppression test is done. If no abnormalities are identified, the diagnosis is acquired idiopathic secondary hypogonadism.
Treatment of Male Hypogonadism
Testosterone replacement therapy
Gonadotropin replacement therapy for restoration of fertility due to secondary hypogonadism
Treatment is directed toward providing adequate androgen replacement conveniently and safely. Although patients with primary hypogonadism may not become fertile with any endocrine therapy, patients with secondary hypogonadism often become fertile with gonadotropin therapy. Testosterone formulations discussed here are those available in the US. Other formulations may be available in other countries.
Testosterone replacement therapy (TRT)
Because exogenous testosterone impairs spermatogenesis, TRT should be avoided, when possible, when subsequent fertility is a concern (unless there is irreversible primary testicular failure), including in secondary hypogonadism. However, if subsequent fertility is not a concern, testosterone replacement therapy alone may be used to treat secondary hypogonadism. Treatment of secondary hypogonadism in boys with gonadotropin replacement therapy (see Treatment of infertility due to hypogonadism Treatment of infertility due to hypogonadism Hypogonadism is defined as testosterone deficiency with associated symptoms or signs, deficiency of spermatozoa production, or both. It may result from a disorder of the testes (primary hypogonadism)... read more ) usually stimulates androgen production as well as spermatogenesis.
TRT can be used for young males who
Have no signs of puberty
Are near age 15
Have had secondary hypogonadism excluded
They may be given long-acting testosterone enanthate 50 mg IM once/month for 4 to 8 months. These low doses cause some virilization without restricting adult height. Older adolescents with testosterone deficiency receive long-acting testosterone enanthate or testosterone cypionate at a dose that is increased gradually over 18 to 24 months from 50 to 100 to 200 mg IM every 1 to 2 weeks. Transcutaneous gel may also be used, although it is more expensive; it could possibly be transferred to others during intimate contact. It is reasonable to convert older adolescents to testosterone gel preparations at adult dosages when their IM dosage has reached the equivalent of 100 to 200 mg every 2 weeks.
Adults with established testosterone deficiency may benefit from replacement therapy. Treatment slows the course of osteopenia, muscle loss, vasomotor instability, loss of libido Libido There are 4 main components of male sexual function: Libido Erection Ejaculation Orgasm read more , depression Depressive Disorders Depressive disorders are characterized by sadness severe enough or persistent enough to interfere with function and often by decreased interest or pleasure in activities. Exact cause is unknown... read more , and occasionally erectile dysfunction Erectile Dysfunction Erectile dysfunction is the inability to attain or sustain an erection satisfactory for sexual intercourse. Most erectile dysfunction is related to vascular, neurologic, psychologic, and hormonal... read more . The effects of testosterone on coronary artery disease Overview of Coronary Artery Disease Coronary artery disease (CAD) involves impairment of blood flow through the coronary arteries, most commonly by atheromas. Clinical presentations include silent ischemia, angina pectoris, acute... read more are not well understood. TRT may improve coronary artery blood flow and may decrease the risk of coronary artery disease. Concerns that TRT increases risk of cardiovascular events have been raised in some studies. However, a large body of expert opinion has refuted these concerns. Advantages of testosterone treatment must be weighed against possible increased cardiovascular risk for each individual patient.
Options for replacement therapy include: a new oral form of testosterone undecanoate taken twice daily
Testosterone gel 1% or 1.62% (5 to 10 g of gel daily to deliver 5 to 10 mg of testosterone daily)
Transdermal axillary solution (60 mg once a day)
A buccal mucosal lozenge (30 mg twice a day)
Transdermal testosterone patch (4 mg once day)
A nasal formulation (one spray of 5.5 mg in each nostril 3 times a day)
Subcutaneous testosterone implants (75 mg/pellet) given as 4 to 6 units placed every 3 to 6 months
IM testosterone enanthate or cypionate (100 mg every 7 days or 200 mg every 10 to 14 days); available for self-injection
Testosterone gel maintains physiologic blood levels more consistently than other treatments, but IM or patch systems are sometimes preferred because of their lower cost. Oral formulations are unpredictably absorbed.
Potential adverse effects of testosterone and its analogs include
Erythrocytosis Secondary Erythrocytosis Secondary erythrocytosis is erythrocytosis that develops secondary to disorders that cause tissue hypoxia, inappropriately increased erythropoietin production, or increased sensitivity to erythropoietin... read more (particularly in men over age 50 receiving IM testosterone)
Venous thromboembolism unrelated to erythrocytosis
Very rarely prostatic enlargement may occur. This is thought to be a physiologic rate of growth due to the normalization of serum testosterone. Prostatic obstructive symptoms are rare. Replacing testosterone to physiologic levels is not thought to cause new prostate cancer or accelerate growth or spread of localized prostate cancer. TRT is thought to have a minimal effect on serum prostate-specific antigen (PSA) levels in men with benign prostatic hyperplasia Benign Prostatic Hyperplasia (BPH) Benign prostatic hyperplasia (BPH) is nonmalignant adenomatous overgrowth of the periurethral prostate gland. Symptoms are those of bladder outlet obstruction—weak stream, hesitancy, urinary... read more and in men with treated prostate cancer. However, product inserts do state that TRT is contraindicated in men with prostate cancer Prostate Cancer Prostate cancer is usually adenocarcinoma. Symptoms are typically absent until tumor growth causes hematuria and/or obstruction with pain. Diagnosis is suggested by digital rectal examination... read more , and men who have or are at high risk of prostate cancer should be counseled and carefully followed with digital rectal examinations and PSA measurements while taking TRT. A prostate biopsy Prostate biopsy Biopsy of the urinary tract requires a trained specialist (nephrologist, urologist, or interventional radiologist). Indications for diagnostic biopsy include unexplained nephritic or nephrotic... read more may be needed if PSA elevation persists after TRT is stopped. Hypogonadal men with effectively treated prostate cancer or suspected of having prostate cancer should seek consultation with an expert.
Men taking supplemental testosterone should be monitored periodically. Hematocrit (Hct), PSA, and testosterone levels should be measured quarterly during the first year of TRT and semiannually thereafter. Digital rectal examination should be offered at the same times. If Hct is ≥ 54%, the testosterone dose should be reduced. Significant increases in PSA level should prompt consideration of prostate biopsy in men who would otherwise be candidates for prostate cancer diagnosis and treatment.
Treatment of infertility due to hypogonadism
Infertility Overview of Infertility Infertility is usually defined as the inability to conceive after 1 year of regular, unprotected sexual intercourse. Infertility is defined as a disease by the World Health Organization (WHO)... read more has many possible causes other than hypogonadism. Infertility due to primary hypogonadism (elevated FSH) does not respond to hormonal therapy. Men with primary hypogonadism occasionally have a few intratesticular sperm that can be harvested with various microsurgical techniques and used to fertilize an egg by assisted reproductive technique (eg, intracytoplasmic sperm injection Intracytoplasmic sperm injection (ICSI) Assisted reproductive techniques (ARTs) involve manipulation of sperm and ova or embryos in vitro with the goal of producing a pregnancy. For assisted reproductive techniques, oocytes and sperm... read more ).
Infertility due to secondary hypogonadism usually responds to gonadotropin replacement therapy. Other symptoms of secondary hypogonadism also respond well to testosterone replacement therapy. If secondary hypogonadism results from pituitary disease, gonadotropin replacement therapy usually is successful. Therapy begins with replacement of luteinizing hormone (LH) and recombinant follicle-stimulating hormone (FSH). Luteinizing hormone replacement is initiated using human chorionic gonadotropin (hCG) (eg, at doses of 1500 IU subcutaneous 3 times a week), with dose adjustments based on subsequent hormone levels. FSH replacement, which is expensive, uses human menotropic gonadotropin (hMG) or human recombinant FSH (eg, at doses of 75-150 IU 3 times a week). Doses may be adjusted based on the results of periodic testing with semen analysis and levels of serum FSH, LH, and testosterone. Once an adequate sperm count is achieved, FSH can be stopped and hCG monotherapy continued.
Most men who have secondary hypogonadism due to a hypothalamic defect (eg, idiopathic hypogonadotropic hypogonadism, Kallmann syndrome Selective Pituitary Hormone Deficiencies ) become fertile with treatment despite sperm counts that are low (eg, < 5 million/mL). When LH and FSH treatment is ineffective, pulsatile gonadotropin-releasing hormone replacement therapy (every 2 hours subcutaneous by a programmable minipump), although less readily available, might be more effective. Most (80 to 90%) of men respond successfully to these regimens.
Levels of FSH and LH help differentiate between primary hypogonadism (high levels) and secondary hypogonadism (low or borderline normal levels).
Age-related symptoms of male hypogonadism include inadequate sexual differentiation (congenital), delayed puberty (childhood onset), and various nonspecific symptoms such as decreased libido, erectile dysfunction, cognitive decline, decrease in percentage of lean body mass, sleep disturbances, and mood changes (adult onset).
Free testosterone levels, which can be calculated and sometimes measured, better reflect gonadal sufficiency than do total testosterone levels.
Diagnosis can be approached systematically, using an algorithm.
Testosterone replacement therapy can relieve symptoms of hypogonadism but does not restore fertility.
Gonadotropin replacement therapy can usually restore fertility in men with secondary hypogonadism.