Updated: 2/12/2018

Male Hypogonadism

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  • Decrease in effective testosterone levels as result of
    • decreased free concentration
      • often as result of decreased production (Leydig and pituitary dysfunction)
      • also result of increased synthesis of SHBG
    • decreased activity at receptor
      • often as result of androgen receptor deficiency
  • May be primary or secondary
    • primary hypogonadism / hypergonadotropic hypogonadism
      • ↓ function of Leydig cells
        • results in testosterone synthesis
        • any dysfunction isolated to Sertoli cells/seminiferous tubules does not result in ↓ testosterone synthesis
        • if testes are cryptorchid, testosterone production is normal because Leydig cells are not affected by ↑ temperature
      • loss of negative feedback of testosterone results in ↑ LH
      • FSH levels are variable based on presence of inhibin
        • ↑ FSH if seminiferous tubule dysfunction is also present
          • inhibin normally released by Sertoli cells to inhibit FSH
          • if damaged that feedback is lost
        • normal FSH if dysfunction is limited to Leydig cells
      • etiologies include
        • alcoholic liver disease
        • damage to Leydig cells as result of trauma, toxins, inflammation, and irradiation
    • secondary hypogonadism / hypogonadotropic hypogonadism
      • ↓ function of hypothalamus/pituitary
      • results in LH and FSH synthesis and consequent testosterone synthesis
      • etiologies include
        • craniopharyngioma
        • pituitary adenoma
  • Symptoms
    • ↓ secondary male characteristics
    • osteoporosis
      • result of dysregulated osteoclast activity (normally ↓ by testosterone)
    • infertility
      • ↓ sperm count
    • impotence

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