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Key Features

Essentials of Diagnosis

  • Diminished libido and erections

  • Fatigue, depression, reduced exercise endurance

  • Decreased growth of body hair

  • Small or normal testes; low serum total testosterone or free testosterone level

  • Luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

    • Low or normal in hypogonadotropic hypogonadism (insufficient gonadotropin secretion by pituitary)

    • Increased in testicular failure (hypergonadotropic hypogonadism)

General Considerations

  • Caused by deficient testosterone secretion by the testes

  • In hypogonadotropic form, FSH and LH deficiency may be isolated or accompanied by other pituitary hormone abnormalities

Hypogonadotropic hypogonadism (Low testosterone with normal or low LH)

  • Causes (Table 26–13) can be primary (failure to enter puberty by age 14) or acquired

  • Causes of acquired hypogonadotropic hypogonadism include

    • Pituitary or hypothalamic tumors

    • Granulomatous diseases

    • Lymphocytic hypophysitis

    • Cushing syndrome

    • Adrenal insufficiency

    • Thyroid hormone excess or deficiency

    • Hemochromatosis

    • Estrogen-secreting tumor (testicular, adrenal)

    • Chronic illness or malnourishment

    • Kallmann syndrome

    • Idiopathic or associated with normal aging or obesity

Table 26–13.Causes of male hypogonadism.
Hypergonadotropic hypogonadism (Testicular Failure with high LH)

  • Causes (Table 26–13)

    • Male climacteric (andropause)

    • Klinefelter syndrome: at least one Y chromosome and at least two X chromosomes (47,XXY et al)

    • Orchitis, eg, mumps, gonorrhea, tuberculosis, leprosy

    • Testicular failure secondary to radiation therapy or chemotherapy

    • Autoimmune, uremia, testicular trauma or torsion, lymphoma, myotonic dystrophy, androgen insensitivity

Clinical Findings

Symptoms and Signs

  • Delayed puberty if congenital or acquired during childhood

  • Decreased libido with acquired hypogonadism in most

  • Erectile dysfunction, hot sweats, fatigue, or depression

  • Infertility, gynecomastia, headache (if pituitary tumor)

  • Decreased body, axillary, beard, or pubic hair but only after years of severe hypogonadism

  • Loss of muscle mass and weight gain due to increased subcutaneous fat

  • Testicular size, as assessed with orchidometer, may decrease but usually remains normal in length (> 6 cm) in postpubertal hypogonadotropic hypogonadism

  • In Klinefelter syndrome, manifestations are variable

    • Generally, testes normal in childhood, but usually become small, firm, fibrotic, and nontender in adolescence

    • Normal onset of puberty, variable degree of virilization, gynecomastia at puberty, tall stature with increased arm span

    • Patients with > 2 ...

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