secondary hypogonadism

Introduction

Failure of adequate hypothalamic or pituitary gonadotropin stimulation.

Etiology

• initial manifestation at the time of puberty
  • generally results from isolated failure of GnRH secretion
  • may be caused by structural pituitary or hypothalamic lesion
  • if accompanied by anosmia -> Kallmann's syndrome
• post-pubertal manifestation
  • intracranial neoplasm
    • prolactinoma
    • craniopharyngioma
  • hemochromatosis
• ostructive sleep apnea
• opioids, anabolic steroids, glucocorticoids
• hypogonadotropic hypogonadism

Laboratory

• 8 AM serum testosterone* < 150 ng/dL (male)
  • MSKAP17 problem with serum testosterone 178 ng/dL
• diminished serum luteinizing hormone (serum LH) & serum follicle-stimulating hormone (serum FSH)
• evidence of other pituitary hormone abnormalities
  • serum prolactin
  • serum thyroid-stimulating hormone (serum TSH)
  • serum ACTH
  • serum growth hormone (GH)
  • serum FSH & serum LH may be inappropriately low
• serum iron, serum ferritin & transferrin saturation if hemochromatosis suspected
• anabolic steroids in urine

* do not measure serum testosterone if patient has regular morning erections, no gynecomastia & normal genitals

Diagnostic procedures

• sleep study if suspected obstructive sleep apnea

Radiology

• MRI of pituitary & hypothalamus

Management

• see testosterone replacement therapy
  • testosterone replacement therapy does not treat infertility
    • it impairs spermatogenesis

More general terms

• hypogonadism

More specific terms

• hypogonadotropic hypogonadism; gonadotropin deficiency

Additional terms

• Kallmann syndrome; hypogonadotropic hypogonadism & anosmia