5 - male hypogonadism

Question 1

what cells produce testosterone? what cells do LH & FSH act on?

Answer 1

leydig cells produce testosterone

LH = act on leydig cells
FSH = act on sertoli cells

Question 2

what is primary male hypogonadism?

Answer 2

low testosterone from problem with testes

• LH made but leydig cells not working to make testosterone. hypothalamus & pituitary functioning normal so make lots of LH & FSH to try make T

= called hypergonadotrophic hypogonadism (since high GnRH, LH & FSH but low testosterone)

Question 3

what is secondary male hypogonadism?

Answer 3

= low testosterone from problem in hypothalamus & pituitary

• low LH & FSH and low testosterone

hypogonadotrophic hypogonadism (since everything low)

Question 4

what are causes of primary hypogonadism?

Answer 4

• congenital like klinefelter’s syndrome
• acquired like testicular trauma/torsion, chemo, varicocele (venous supply problem), orchitis (inflammation of testes like mumps), infiltrative disease, meds like glucocorticoids

Question 5

what is Klinefelter’s syndrome? how does it present?

Answer 5

additional X-chromosome (47 XXY). not inherited, caused by nondisjunction (not proper separation in meiosis)

presents = presents late (when trying to have family), frontal baldness, poor beard growth, female-type pubic hair growth, narrow shoulders, wide hips, long arms & legs, small testicular size, gynaecomastia

Question 6

what are causes of secondary hypogonadism?

Answer 6

• congenital like kallmann’s syndrome
• acquired like pituitary damage from tumours, infection etc, hyperprolactinaemia, obesity, acute illness, eating disorders

Question 7

what is Kallmann’s syndrome? presents?

Answer 7

= genetic disorder characterised by isolated GnRH deficiency

presents = reduced sense of smell, also unilateral renal agenesis, red-green colourblindness, cleft palate, bimanual synkinesis

Question 8

what is presentation of pre-pubertal hypogonadism?

Answer 8

*basically just think like child not gone through puberty

• small testes
• decreased body hair, high pitched voice, low libido
• gynaecomastia
• eunuchoidal (tall, slim, long arms & legs)
• decreased bone & muscle mass

Question 9

what is presentation of post pubertal hypogonadism?

Answer 9

• normal skeletal proportions, normal penic prostate and normal voice
• decreased libido, decreased spontaneous erections
• decreased pubic/axillary hair. shave less often
• decreased testicular volume
• gynaecomastia
• lose muscle & bone mass
• decreased energy & motivation

Question 10

what is steps to male hypogonadism diagnosis?

Answer 10

• look at semen
• do morning testosterone test (it peaks in early morning like cortisol) = repeat twice if low to make sure
• measure LH & FSH to determine primary or secondary
• if high LH & FSH = karyotype & iron studies

Question 11

how does testosterone travel? why important? ( hint - about measuring)

Answer 11

travels bound to sex hormone binding globulin = can measure total testosterone and SHBG to calculate free testosterone

Question 12

what is management of male hypogonadism?

Answer 12

• GnRH therapy if want to restore fertility
• if fertility unimportant then try maintain sexual function and improve quality of life = give testosterone replacement therapy (gel or oral capsules)
  *contraindication if prostate cancer or severe sleep apnea