Male Hypogonadism

1.  Hypogonadism pre-puberty:
   1. o p/c: gynecomastia, high pitched voice, testicular volume <5ml, penile length <5cm, arm span 6cm or more than height, delayed bone age, reduced muscle bulk, absent pubic hair, absent erections, absent libido.
2.  If onset is post-puberty:
   1. o p/c: normal body proportions, facial wrinkling, gynecomastia, pigmented scrotum, osteoporosis, testicular volume >15ml, penile length >5cm, reduced muscle bulk, reduced pubic hair, reduced erections, reduced libido.
   2. o Acquired hypogonadism affects 20% of all men
3.  Primary hypogonadism = testicular failure:
   1. o Main causes are systemic disease, renal failure, and alcoholic liver cirrhosis.
   2. o Adult men with mumps – 25% develop orchitis and half of these develop to late gonadal failure (primary)
   3. o Viral causes are not uncommon
   4. o Testicular trauma, torsion, gonadal RT or systemic CT drugs
4.  Specific genetic diseases:
   1. o Kleinfelter’s syndrome (XXY):1/1000, small testes, gynecomastia, eunuch-like appearance from testosterone deficiency, azoospermia, and infertility.
5.  Secondary hypogonadism = hypothalamic-pituitary failure:
   1. o Caused by severe illness, malnutrition, pituitary disease, hyperprolactinaemia.
   2. o Kallman’s syndrome: a genetic X-linked syndrome, autosomal dominant or recessive, M>F (4>1), 1/10,000, causes isolated failure of hypothalmic gonadotrophin-releasing hormone (GnRH) release with anosmia. MRI shows absent olfactory bulbs.
6.  Mx of male hypogonadism:
   1. o Androgen replacement therapy – will relieve symptoms and prevent osteoporosis – but will not improve fertility (which is irreversible in primary failure).
   2. o Gonadotrophins can be used to induce fertility in secondary hypogonadism.