Aetiology

There are four aetiological classes of hypogonadism in the male (1,2):

• primary hypogonadism - i.e. hypogonadism due to testicular failure
  • congenital primary gonadal disease
  • acquired primary gonadal disease
    
    
• secondary hypogonadism - may be due to reduced gonadotrophins due to hypothalamic-pituitary disease
  • congenital e.g. Kallman's syndrome
  • secondary e.g. pituitary tumours
  • reversible secondary hypogonadism may also be the result of systemic illness e.g. (end-stage respiratory or renal disease), obesity, hyperprolactinaemia, long-term excessive exercise (1), poor nutritional status, supra-physiological doses of steroids, drugs (spironolactone, ketoconazole, marijuana)

References:

1. Salonia A, Rastrelli G, Hackett G, et al. Paediatric and adult-onset male hypogonadism. Nat Rev Dis Primers. 2019 May 30;5(1):38.
2. Matsumoto AM. Diagnosis and evaluation of hypogonadism. Endocrinol Metab Clin North Am. 2022 Mar;51(1):47-62.