Pituitary Gonadal Flashcards
Sex hormone binding globulin
Binds testosterone
Increases in aging, cirrhosis, estrogen, anticonvulsant, HIV, decreased TSH
Decreases in nephrotic syndrome, increased TSH, androgens, obese
Sertoli cells
Secrete sperm
Androgen deficiency signs
Decreased libido Decreased spontaneous erection Gynecomastia Loss of body hair Hot flashes
Prolactin
Inhibits LH, produces milk
Measure PRL when hypogonadism suspected
Stimulated by TRH
Inhibited by dopamine
Treat with dop agonist: bromocriptine, cabergoline
Spermatogenesis
Requires hCG or LH, FSH
Give HCG (LH mimic) and FSH in congenital 2nd) hypogonadism
Androgen deficiency
Different among stages
Genital development
Muscles, voice
Adult: sexual dysfunction, osteoporosis
Gynecomastia
Primary hypogonadism
Low testosterone
High LH&FSH l, long arms and legs
From testicles, klinefelter 47XXY
Tx: testosterone
Secondary hypogonadism
Low T, low LH/FSH
Hyperprolactinemia low GnRH /LH
Congenital lack GnRH
Kallman
From pituitary,
Tx: HCG (LH analog) or testosterone
Infertility
Many take androgen/ testosterone which blocks LH has and FSH
Tx: clomen (releases LH&FSH)
Androgen abuse
Suppress testicular function, sperm production
Gynecomastia
Decrease HDL increase LDL
Hepatotoxicity
Primary Ovarian insufficiency
Gonadal dysgenesis: ovaries lack follicles and lack estrogen
45 XO turner
short stature, osteoporosis
Low E2 increases FSH/LH
Menopause Estrogen therapy contraindications
Estrogen dependent tumors
Liver disease
Thromboembolic disease
Use progesterone if intact uterus to oppose estrogen
Secondary ovarian insufficiency - hyperprolactinemia
Secondary amenorrhea
Alters pulsatile GnRH
Decreased GnRH receptors
Decreased FSH, LH
TRH stimulates prolactin release
Lack of dopamine stimulates PRL
Ovarian hyperfunction- hyperandrogenism PCOS
Polycystic ovary syndrome
Increase LH/FSH (>2) androgen secretions (T>200)
Hirsutism, acne, insulin resistance
Adrenal Hyperandrogenism
Impaired cortisol synthesis
21 hydroxylase deficiency
More downstream androgen
Give hydrocortisone for neg feedback on pituitary ACTH
Fludrocortisone
ADH (vasopressin)
Secreted forms posterior pituitary
Vasoconstriction: Gaq
water retention: Gas
Regulated by osmolality and plasma volume
Anterior pituitary GPLAT
ACTH TSH Growth hormone Prolactin LH/FSH
Growth hormone
Bone growth, density
Muscle mass
Tumor promotion
Protein synthesis
Lipolysis
Simulated by GHRH, dopamine, 5HT
Inhibited by somatostatin, IGF1
GH excess
Gigantism, acromegaly
Give bromocriptine dop agonist
Somatostatin, octreotide
GH receptor antagonist: pegvisomant
GH deficiency
Give GH replacement therapy
Sermorelin, somatotropin
Mercasermin IGF1 for laron, pygmies
Oxytocin
Spikes during labor causing uterine contractions
Lets milk out of breast
Bonding, maternal behavior
Gaq IP3 Ca muscle contraction
Agonist induce labor: Pitocin
Antagonist suppress premature labor: tractocile
LH
Forms corpus luteum in Female
Produces testosterone in male
FSH
Initiates ovulatory cycle
Stimulates Sertoli cell spermatogenesis
LH FSH excess
Testicular failure, Turner syndrome
Early puberty, irregular cycle, infertility
Tx: GnRH antagonist, continuous GnRH agonist (downregulation)
Gonadorelin acetate for infertility
LH/FSH deficiency
Delayed puberty
Pulsatile GnRH agonist: leuprolide, nafarelin
Testosterone rate limiting step
LH induced cholesterol conversion to Pregnenolone
Androgen cortisol balance
Excess androgen loss of growth potential
Excess cortisol decrease growth, increase BPH Cushing’s
Hyperprolactinemia
May be due to hypothyroidism or dopamine deficiency
