HPA Flashcards
(18 cards)
Function of FSH
Stimulate ovarian follicle development
Function of LH
In women: causes midcycle ovulation
In Men: drives testosterone secretion from leydig cells
Function of GnRH
Stimulates FSH and LH release
Inhibitors of LH and FSH
Testosterone
Prolactin
Estrogen
Prolactin inhibitor
Dopamine
Stimulator of prolactin release
TRH
This explains why patient with primary hypothyroidism can have galactorrhea and also infertility because prolactin inhibit FSH and LH
Effect of pituitary tumor
Compressive effect of the optic chasm leads to bitemporal hemianopsia
Hypo or hyper secretion
Cortisol has a circadian rhythm
Peaks in the morning
Lowest at midnight
This explains why early morning cortisol (8am cortisol) is used to assess for deficiency of cortisol
Midnight salivary cortisol use to check for excess cortisol
Synacthen test
Stimulatory test used to evaluate for cortisol deficiency , primary adrenal failure and Pituitary ACTH reserve
Not to used in acute situations like pituitary apoplexy or post pituitary surgery
Mediator of growth hormone function
IGF.1
Dynamic pituitary test
Used to assess hormones that have pulsatile secretion circadian rhythm
Insulin tolerance test
Gold standard test for ACTH and GH reserve
Cortisol response’> 550nmol /l
GH response : 3ug/dl
Contraindications: IHD
Epilepsy
Pituitary macroadenoma
> 1cm
Pituitary microadenoma
<1cm
Secondary causes of hypertension
Acromegaly
Hyperthyroidism
Hyperaldosteronism
Cushing syndrome
Pheochromocytoma
Oral glucose tolerance test for acromegaly
75g OGTT causes GH suppression by < 1ug/l in normal people and failure to suppress suggests autonomous secretions and diagnosis of acromegaly
Somatostatin analogue
Octreotide
Lanreotide
Pasireotide
Given monthly
