male hypogonadism Flashcards
what stimulates the hypothalamus to release GnRH
kisspeptin
what stimulates the anterior pituitary to release LH and FSH
GnRH
which cells produce testosterone
Leydig cells under control of LH
what is the majority of testosterone bound to
SHBG and albumin
what is testosterone converted to
dihydrotestosterone and oestradiol
what is male hypogonadism
testosterone deficiency
what does primary hypogonadism mean
testes primarily affected
- decreased testosterone means decreased negative feedback
- anterior pituitary secretes higher amounts of LH/FSH
- hypergonadotrophic hypogonadism
- spermatogenesis is affected more tan testosterone production
what is secondary hypogonadism
hypothalamus/pituitary affected, testes capable of normal function
- LH/FSH low despite low testosterone
- hypogonadotrophic hypogonadism
- spermatogensis and testosterone production are equally affected
congenital causes of primary hypogonadism
- klinefelter’s syndrome
- cryptorchidism
- Y-chromosome microdeletions
acquired causes of primary hypogonadism
- testicular trauma
- chemotherapy
- radiation
- varicocele
- orchitis
- infiltrative disease
- medications
what is Klinefelter’s syndrome caused by
nondisjunction
-47 XXY
symptoms of male hypogonadism
- poor beard growth
- small testicles
- female pubic hair pattern
- long arms and legs
- wide hips
- breast development
- narrow shoulders
congenital causes of secondary hypogonadism
- kallmann’s syndrome
- prader-Willi syndrome
acquired causes of secondary hypogonadism
- pituitary damage (trauma, tumours, infiltrative disease etc)
- hyperprolactinaemia
- obesity, diabetes
- medications
- acute systemic illness
- eating disorders
- excessive exercise
what is kallmann’s syndrome
genetic disorder characterised by isolated GnRH deficiency and hyposmia or anosmia
pre-pubertal symptoms of hypogonadism
- small sex organs
- decreased body hair
- high pitched voice
- low libido
- gynaecomastia
- tall, slim, long arms and legs
- decreased bone and muscle mass
post-pubertal symptoms of hypogonadism
- normal skeletal proportions
- normal penis/prostate size
- normal voice
- decreased libido and erections
- decreased pubic hair
- decreased testicular volume
- gynaecomastia
- decreased muscle and bone mass
- decreased energy and motivation
how to diagnose hypogonadism
- measure AM testosterone
- repeat if low
- if still low then measure LH/FSH
- these should be elevated if primary
- then karyotyping or iron studies
- if LH/FSH normal then exclude meds, MRI, iron studies, look at prolactin and pituitary hormones
why can total testosterone be misleading
-only free portion is biologically active
treatment for hypogonadism
testosterone replacement therapy
- testogel
- testosterone undecanoate oral capsules
- testosterone undecanoate intra-muscular injection (Nebido)
- testosterone enanthate/propionate/cipionate intramuscular injection (Sustanon)
contraindications for testosterone replacement therapy
- confirmed hormone responsive cancer
- possible prostate cancer
- haematocrit
- severe sleep apnoea/heart failure
how often is testosterone replacement monitored
3-6 monthly while starting treatment, annually thereafter
