Male Hypogonadism Flashcards
what is the hypothalamus stimulated by?
kisspeptin on kisspeptin receptors to release GnRH
testicular functions
spermatogenesis
testosterone production
how is testosterone transported in the blood
bound or free
what is testosterone bound to?
SHBG and albumin
what can testosterone be converted to?
dihydrotestosterone and oestradiol (aromatase in adipose tissue- gynecomastia in men)
what is male hypogonadism
a testosterone deficiency
primary hypogonadism cause
testes
secondary hypogonadism cause
hypothalamic/pituitary pathway
pre-pubertal presentation of hypogonadism
small male sexual organs e.g. small testes, penis and prostate
decreased body hair, high pitched voice and low libido
gynaecomastia
eunuchoid habitus (tall, slim, long arms and legs)
decreased bone mass (low estradiol which ones from breakdown on testosterone)
decreased muscle mass (related to testosterone level)
post-pubertal presentation of hypogonadism
normal skeletal portions, penis/prostate size and voice
decreased libido and spontaneous erections
decreased pubic/axillary hair, reduced shaving frequency
decreased testicular volume
gynaecomastia
decreased muscle and bone mass
decreased energy and motivation
vision defects if pituitary tumour
diagnosis- why is free testosterone misleading?
only the free portion is biologically active
diagnosis
measure total testosterone and SHBG to calculate free testosterone (binds loosely to albumin and tightly to SHBG)
when should testosterone be measured
8-11am
management
testosterone replacement therapy
contraindications of hormone replacement therapy
hormone responsive cancer (prostate/breast)
possible prostate cancer (raised PSA, suspicious prostate on DRE)
haematocrit >50%
severe sleep apnoea/heart failure
