male hypogonadism Flashcards
describe the male HPG axis in terms of hormones
Hypothalamus is stimulated by kisspeptin to release pulses of gonadotropin-releasing hormone (GnRH)
Anterior pituitary is stimulated by GnRH to release luteinising hormone (LH) and follicle stimulating hormone (FSH)
Gonads (testes) are stimulated by LH/FSH to produce testosterone
Testosterone provides NEGATIVE FEEDBACK to hypothalamus and pituitary
where is testosterone produced?
leydig cells under control of LH
what is the definition of male hypogonadism?
A clinical syndrome comprising of signs, symptoms and biochemical evidence of testosterone deficiency
describe primary male hypogonadism
Testes primarily affected
Decreased testosterone = decreased -ve feedback
Anterior pituitary secretes higher amounts of LH/FSH
spermatogenesis is affected more than testosterone production
what are the congenital causes of primary male hypogonadism?
Klinefelter’s syndrome
Cryptorchidism (abscence of at least one testicle)
Y-chromosome microdeletions
what are some acquired causes of primary male hypogonadism?
Testicular trauma/torsion
Chemotherapy/radiation
Varicocele
Orchitis (mumps infection)
Infiltrative diseases (e.g. haemochromatosis)
Medications (glucocorticoids, ketoconazole)
what are congenital causes of secondary male hypogonadism?
kallmann’s syndrome (isolated hypogonadotrophic hypogonadism)
prader-willi syndrome
what are some acquired causes of secondary hypogonadism?
pituitary damage
hyperprolactinaemia
obesity & diabetes
medications (steroids and opiods)
acute illness
eating disorders and excessive exercise
what is kallmann’s syndrome?
genetic disorder characterised by isolated GnRH deficiency and hyposmia or anosmia
what abnormalities is kalmann’s syndrome associated with?
unilateral renal agenesis, red-green colour blindness, cleft lip/palate and bimanual synkinesis
what are pre-pubertal signs & symptoms of hypogonadism?
Small male sexual organs e.g. small testes (volume <5 mL), penis and prostate
Decreased body hair, high-pitched voice, low libido
Gynaecomastia
‘Eunuchoidal’ habitus (tall, slim, long arms and legs)
Decreased bone and muscle mass
what are post pubertal symptoms of hypogonadism?
Normal skeletal proportions, penis/prostate size and voice
Decreased libido, decreased spontaneous erections
Decreased pubic/axillary hair, reduced shaving frequency
Decreased testicular volume
Gynaecomastia
Decreased muscle and bone mass
Decreased energy and motivation
what is the management of male hypogonadism?
testosterone replacement therapy
what are the side side effects of taking testosterone replacement therapy?
hormones responsive cancers (prostate, breast)
severe sleep apnoea
heart failure
