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Morbidity for men and women with hypogonadism includes infertility and an increased risk of osteoporosis; there is no increase in mortality.

Hypogonadotropic hypogonadism (see the image below) is one of several types of hypogonadism.

History

Considerations in the evaluation of males with hypogonadism include the following:

Developmental anomalies associated with the genital system (eg, hypospadias, micropenis, and cryptorchidism)[1]

For postpubertal males, the rate of beard growth, libido and sexual function, muscle strength, and energy levels

Possible causes of acquired testicular failure (eg, mumps orchitis, trauma, radiation exposure of the head or testes, and chemotherapy)

Drugs that may interrupt testicular function: Including agents that interfere with testosterone synthesis, such as spironolactone, cyproterone, marijuana, heroin, and methadone

Considerations in the evaluation of females with hypogonadism include the following:

Signs associated with Turner syndrome (eg, lymphedema, cardiac or renal congenital anomalies, and short growth pattern)

Age of menarche

Physical examination

Considerations in the physical examination of males with hypogonadism include the following:

Evaluation of the testes: This is the most important feature of the physical examination; determine whether both testes are palpable, their position in the scrotum, and their consistency; testes size can be quantitated by comparison with testicular models (orchidometer), or their length and width may be measured

Examination of the genitalia for hypospadias

Examination of the scrotum to see if it is completely fused

Evaluation of the extent of virilization

Staging of puberty: Use the Tanner criteria for genitalia, pubic hair, and axillary hair

Examination for signs of Klinefelter syndrome (eg, tall stature, especially if the legs are disproportionately long, gynecomastia, small or soft testes, and a eunuchoid body habitus)

Considerations in the physical examination of females with hypogonadism include the following:

Examination of the genitalia is important

Determination of the extent of androgenization: May be adrenal or ovarian in origin and is demonstrated in pubic and axillary hair

Determination of the extent of estrogenization: As evidenced by breast development and maturation of the vaginal mucosa

Examination for signs of Turner syndrome (eg, short stature, webbing of the neck [such as pterygium colli], a highly arched palate, short fourth metacarpals, widely spaced nipples, or multiple pigmented nevi)

See Clinical Presentation for more detail.

The following studies may be indicated in males with hypogonadism:

Follicle-stimulating hormone (FSH) levels

Luteinizing hormone (LH) levels

Prolactin levels

Testosterone levels

Thyroid function

Seminal fluid examination

Karyotyping

Testicular biopsy

For males after puberty, the Guidelines of the Endocrine Society[2] require that the diagnosis of hypogonadism be based on symptoms and signs of hypogonadism plus the presence of a low testosterone level measured on at least 2 occasions.

The following studies may be indicated in females with hypogonadism:

Additional tests in the evaluation of patients with hypogonadism include the following:

Adrenocorticotropic hormone (ACTH) stimulation testing: In patients in whom a form of congenital adrenal hyperplasia is suspected, adrenal steroid synthesis is best evaluated by performing a cosyntropin (ACTH 1-24) stimulation test

Luteinizing-hormone releasing hormone (LHRH) stimulation testing: To distinguish between true hypogonadotropic hypogonadism and constitutional delay in growth and maturation

Testicular tissue testing: If the testes are not palpable and if it is not certain whether any testicular tissue is present, administering human chorionic gonadotropin (hCG) and measuring testosterone response may be helpful

See Workup for more detail.

Hormonal replacement

The simplest and most successful treatment for males and females with either hypergonadotropic or hypogonadotropic hypogonadism is replacement of sex steroids, but the therapy does not confer fertility or, in men, stimulate testicular growth.

When fertility is desired, an alternative therapy for men with hypogonadotropic hypogonadism is administration of pulsatile LHRH or injections of hCG and FSH. (In patients with hypergonadotropic hypogonadism, fertility is not possible.)

In a 6-year European study of men being treated for hypogonadism, long-term transdermal testosterone treatment did not increase prostate-specific antigen (PSA) levels or influence prostate cancer risk.[3, 4]

Investigators used data from a 5-year, open-label extension of a 1-year trial of a transdermal testosterone patch (Testopatch) in men with hypogonadism. Study subjects wore two 60 cm2 patches, each of which delivered 2.4 mg of testosterone per day. More than 90% of patients had PSA concentrations below 2 ng/mL during the 6-year study, and no prostate cancer was found in patients over the course of the trial.

See Treatment and Medication for more detail.

Hypogonadism manifests differently in males and in females before and after the onset of puberty.[5] If onset is in prepubertal males and testosterone replacement is not instituted, the individual has features of eunuchoidism, which include sparse body hair, poor development of skeletal muscles, and delay in epiphyseal closure, resulting in long arms and legs. When hypogonadism occurs in postpubertal males, lack of energy and decreased sexual function are the usual concerns. In females with hypogonadism before puberty, failure to progress through puberty or primary amenorrhea is the most common presenting feature. When hypogonadism occurs in postpubertal females, secondary amenorrhea is the usual concern.

The gonad (ovary or testis) functions as part of the hypothalamic-pituitary-gonadal axis. A hypothalamic pulse generator resides in the arcuate nucleus, which releases luteinizing hormone (LH)-releasing hormone (LHRH), which is also termed gonadotropin-releasing hormone (GnRH), into the hypothalamic-pituitary portal system. Data suggest that a gene named KISS is important in the development of the LHRH-secreting cells.[6, 7]

In response to these pulses of LHRH, the anterior pituitary secretes follicle-stimulating hormone (FSH) and LH, which, in turn, stimulate gonadal activity. The increase in gonadal hormones results in lowered FSH and LH secretion at the pituitary level, completing the feedback loop. In the testes, LH stimulates Leydig cells to secrete testosterone, whereas FSH is necessary for tubular growth. In the ovaries, LH acts on theca and interstitial cells to produce progestins and androgens, and FSH acts on granulosa cells to stimulate aromatization of these precursor steroids to estrogen.

Hypogonadism may occur if the hypothalamic-pituitary-gonadal axis is interrupted at any level. Hypergonadotropic hypogonadism (primary hypogonadism) results if the gonad does not produce the amount of sex steroid sufficient to suppress secretion of LH and FSH at normal levels. Hypogonadotropic hypogonadism may result from failure of the hypothalamic LHRH pulse generator or from inability of the pituitary to respond with secretion of LH and FSH. Hypogonadotropic hypogonadism is most commonly observed as one aspect of multiple pituitary hormone deficiencies resulting from malformations (eg, septooptic dysplasia, other midline defects) or lesions of the pituitary that are acquired postnatally. In 1944, Kallmann and colleagues first described familial isolated gonadotropin deficiency. Recently, many other genetic causes for hypogonadotropic hypogonadism have been identified.

Normosmic hypogonadotropic hypogonadism, in which the sense of smell is not disrupted, has been associated with mutations in GNRH1, KISS1R, and GNRHR genes. Although their exact functions are unclear, the genes TAC3 and TACR3 have also been associated with normosmic hypogonadotropic hypogonadism. Kallmann syndrome (anosmic hypogonadotropic hypogonadism) has been associated with mutations in KAL1, FGFR1, FGF8, PROK2, and PROKR2 genes. The relationship with Kallmann syndrome is thought to be because these genes are all related to the development and migration of GnRH neurons. Mutations of an additional gene, CHD7, which has been associated with CHARGE syndrome, has also been found in patients with both normosmic or anosmic hypogonadotropic hypogonadism.

In women with hypergonadotropic hypogonadism (ie, gonadal failure), the most common cause of hypogonadism is Turner syndrome, which has an incidence of 1 case per 2,500-10,000 live births. In men with hypergonadotropic hypogonadism, the most common cause is Klinefelter syndrome, which has an incidence of 1 case per 500-1000 live births. Hypogonadotropic hypogonadism is more rare.

No racial predilection has been described.

Hypergonadotropic hypogonadism is more common in males than in females because the incidence of Klinefelter syndrome (the most common cause of primary hypogonadism in males) is higher than the incidence of Turner syndrome (the most common cause of hypogonadism in females). Incidence of hypogonadotropic hypogonadism is equal in males and females.

Hypogonadism may occur at any age; however, consequences differ according to the age at onset. If hypogonadism occurs prenatally (even if incomplete), sexual ambiguity may result. If hypogonadism occurs before puberty, puberty does not progress. If hypogonadism occurs after puberty, infertility and sexual dysfunction result.

No increase in mortality is observed in patients with hypogonadism. Morbidity for men and women includes infertility and an increased risk ofosteoporosis. In women, an increased risk of severe osteoporosis is noted. In men, hypogonadism causes decreased muscle strength and sexual dysfunction.

Men and women with hypogonadism can lead a normal life with hormone replacement.

Approximately 20-25% of females with Turner syndrome have some spontaneous puberty. Spontaneous estrogenization occurs more commonly in women with mosaic karyotypes and those karyotypes with an abnormal second X chromosome, such as 46,XXiq or 46,XXip. Reports exist of women with mosaic Turner syndrome becoming pregnant without in vitro fertilization.

For patient education resources, see theMen's Health CenterandWomen's Health Center, as well asImpotence/Erectile DysfunctionandAmenorrhea.

For both males and females with hypogonadism, determining whether evidence of a genital abnormality is present at birth or determining the timing and extent of puberty is important. In addition, because Kallmann syndrome (hypogonadotropic hypogonadism and anosmia [ie, lack of a sense of smell]) is a common cause of hypogonadotropic hypogonadism, inquiring about the sense of smell is important.

Physical findings may include the following:

The following causes of hypogonadism are noted:

Hypogonadotropic hypogonadism

See the image below.

Causes of hyogonadotropic hypogonadism include the following:

CNS disorders

Hypergonadotropic hypogonadism in males

Hypergonadotropic hypogonadism in females

Genetics of hypogonadotropic hypogonadism

To date, numerous genes have been identified as causes of hypogonadotropic hypogonadism. The genes include the following:

KALis located on the X chromosome, just below the pseudoautosomal region. An abnormality in this gene results in Kallmann syndrome, which is characterized by anosmia and hypogonadotropic hypogonadism.FGFR1, FGF8, PROK2,andPROKR2have also been associated with Kallmann syndrome. The relationship with Kallmann syndrome is thought to be due to the relation of these genes to the development and migration of gonadotropin-releasing hormone (GnRH) neurons.

TheDAX1gene is associated with X-linked adrenal hypoplasia congenita (hypogonadotropic hypogonadism and adrenal insufficiency).

GNRHRis the gene associated with the GnRH (LHRH) receptor.

GNRH1, KISS1R,andGNRHRgenes have been associated with normosmic (sense of smell is not disrupted) hypogonadotropic hypogonadism.

TAC3andTACR3mutations have also been associated with normosmic hypogonadotropic hypogonadism, although their exact functions are unclear.

CHD7mutation, which has been associated with CHARGE syndrome, has also been found in patients with both normosmic and anosmic hypogonadotropic hypogonadism.

PC1is the gene for prohormone convertase 1. Abnormality of this gene causes hypogonadotropic hypogonadism and defects in prohormone processing.

In addition, mutations in thePROP1gene have resulted in absence of several pituitary hormones, including growth hormone, thyroid-stimulating hormone, prolactin, and gonadotropins.PROP1encodes a protein expressed in the embryonic pituitary, which is necessary for function ofPOU1F1(formerlyPIT1), which codes for a pituitary transcription factor.

In addition, mutation of the geneHESX1has been associated with septooptic dysplasia, which may include poor development of the pituitary.

The following studies may be indicated in hypogonadism:

Pelvic ultrasonography may be helpful in females.

Adrenocorticotropic hormone (ACTH) stimulation testing: In patients in whom a form of congenital adrenal hyperplasia is suspected, adrenal steroid synthesis is best evaluated by performing a cosyntropin (ACTH 1-24) stimulation test. Baseline serum adrenocortical hormone levels are measured, then 0.25 mg of cosyntropin is intravenously injected, and serum hormone levels are remeasured after 60 minutes. Precursor product ratios are compared with those in age-matched control subjects to determine whether a steroidogenic defect is involved in sex hormone synthesis.

Luteinizing-hormone releasing hormone (LHRH) stimulation testing: To distinguish between true hypogonadotropic hypogonadism and constitutional delay in growth and maturation, performing a stimulation test with LHRH may be helpful.

LHRH is intravenously injected, and LH and FSH levels are determined at 15-minute intervals following LHRH administration.

A shortened version of the study has been used, in which LHRH is subcutaneously injected, and the specimen for LH and FSH levels is taken at 30-40 minutes.

Obtaining LHRH for testing over the past several years has been difficult. Some centers have substituted testing LH response to aqueous leuprolide.

Testicular tissue testing: If testes are not palpable and whether any testicular tissue is present is unclear, administering human chorionic gonadotropin (hCG) and measuring testosterone response may be helpful.

Bone age may be helpful in distinguishing hypogonadism from constitutional delay in growth and maturation. Timing of onset of puberty is related more to bone age than to chronologic age. Distinguishing hypogonadism from constitutional delay in growth and maturation is often difficult until the bone age is at a point adequate for pubertal development.

Occasionally, testicular biopsy findings are helpful, particularly if azoospermia or oligospermia is present.

In prepubertal patients with hypogonadism, treatment is directed at initiating pubertal development at the appropriate age. All such treatment is hormonal replacement therapy. Although the simplest and most successful treatment for both males and females with either hypergonadotropic or hypogonadotrophic hypogonadism is replacement of sex steroids, in hypogonadotropic hypogonadism, the therapy does not confer fertility or, in men, stimulate testicular growth.

An alternative for men with hypogonadotropic hypogonadism has been treatment with pulsatile LHRH or hCG, either of which can stimulate testicular growth. Because such treatment is more complex than testosterone replacement, and because treatment with testosterone does not interfere with later therapy to induce fertility, most male patients with hypogonadotropic hypogonadism prefer to initiate and maintain virilization with testosterone.

At a time when fertility is desired, it may be induced with either pulsatile luteinizing hormone-releasing hormone (LHRH) or (more commonly) with a schedule of injections of human chorionic gonadotropin (hCG) and follicle-stimulating hormone (FSH).

Read more:
Hypogonadism - Medscape

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