Male hypogonadism Flashcards
what is the hypothalamus stimulates by
kisspeptin to release pulses of gonadotropin releasing hormone- GnRH
what is the anterior pituitary stimulated by to release
GnRH to release LH and FSH
what are the gonads stimulated by
LH/FSH to produce testosterone
what provides negative feedback to hypothalamus and pituitary
testosterone
what is testosterone produced by
leydig cells under control of LH
what is testosterone converted to
dihydrotestosterone - highly active form and oestradiol
what is male hypogonadism
low/ reduced gonadal testicular function
primary hypogonadism
problem with testes
decreased testosterone - decreased negative feedback
anterior pituitary secretes higher amunts of lH/FSH
spermatogenesis affected more than testosterone production
secondary hypogonadism
problem with hypothalamus/ anterior pituitary
spermatogenesis and testosterone production affected equally
LH/FSH low despite low testosterone
causes of primary hypogonadism
Klinefelter’s syndrome
Cryptorchidism
Y-chromosome microdeletions
Testicular trauma/torsion
Chemotherapy/radiation
Varicocele
Orchitis (mumps infection)
Infiltrative diseases (e.g. haemochromatosis)
Medications (glucocorticoids, ketoconazole)
most common genetic cause of hypogonadism
klinefelters syndrome
non disjunction
usually 47,XXY
affected men are typically infeertile
signs in klinefelters syndrom
breast development
female type hair pubic pattern
long arms and legs
wide hips
narrow shoulders
poor beard growth
frontal baldness/ absent
fewer chest hairs
causes of secondary hypogonadism
Kallmann’s syndrome (“isolated hypogonadotrophic hypogonadism”)
Prader-Willi syndrome
Pituitary damage
Tumours
Infiltrative disease
Infection (TB)
Apoplexy
Head trauma
Hyperprolactinaemia
Obesity, diabetes
Medications (steroids, opioids)
Acute systemic illness
Eating disorders, excessive exercise
kallmans syndrome
geentc disorder characterised by gnrh def and hyposmia or anosmia
pre pubertal onset symptoms and signs 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
post pubertal symptoms and signs
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
diagnosis of hypogonadism
measure AM testosterone
measure LH/FSH
if lH/FSH elevated
primary
if LH/FSH low/ inappropritely normal
secondary
when should testosterone be measured
between 8am -11am
what can cause increased concentrations of SHBG
ageing
hyperthyroidism
liver disease
HIV
use of anticonvulsants
what can cause decreased concentrations of SHBG
obesity
insulin resistance and diabetes
hypothyroidism
growth hormone excess
glucocorticoids
androgens
progestins
nephortic syndrome
management if fertility is important
GnRH or gonadotrophin therapy
management if fertility not important
Establish/maintain secondary sexual characteristics
Maintain sexual function
Improve body composition
Improve quality of life
by giving testosterone replacement therapy
what is testosterone replacement therapy contraindicated in
Confirmed hormone responsive cancer (e.g. prostate/breast)
- Possible prostate cancer (e.g. raised PSA, suspicious prostate on DRE)
- Haematocrit >50%
- Severe sleep apnoea/heart failure
monitoring of testostrone replacement therapy
3-6 monthly whilst starting treatment then annually
