Endocrinology Flashcards
Posterior pituitary hormones
Oxytocin, ADH
Anterior pituitary hormones
TSH, ACTH, FSH/LH, GH, prolactin, endorphins
Direct secretion of hormones from the hypothalamus
Posterior pituitary - oxytocin, ADH
Zones of the adrenal gland
Glomerulosa, Fasiculata, Reticularis, Medulla
Mineralocorticoids
Aldosterone
Secreted by glomerulosa in response to RAS
Increases Na and HCO3, decreases K
Glucocorticoids
Cortisol (high AM, low at MN)
Secreted by fasiculata in response to ACTH
Increases glucose and BP
Most common defect in CAH
21-hydroxylase deficiency (95%)
Classic CAH
salt wasting (no aldo), hypotension (no cortisol), virilization (excess DHEA)
Primary causes of adrenal insufficiency
Congenital (x-linked)
Adrenal damage
Defects in cholesterol synthesis (Smith-Lemli-Optiz)
Peroxisomal disorders (ALD, Zellweger)
Secondary adrenal insufficiency
No salt-wasting or hyperpigmentation
Due to lack of ACTH
Triple A syndrome (Allgrove)
ACTH resistance, achalasia, alacrima
Autoimmune Polyglandular Syndrome (type 1)
Hypoparathyroidism, adrenal insufficiency, candidiasis
Autoimmune Polyglandular Syndrome (type 2)
Hypothyroidism, adrenal insufficiency, DM type 1
Liddle syndrome
Activation of Na channel causes mineralocorticoid excess and hypertension
Pheochromocytoma rule of 10’s
10% = extra-adrenal, malignant, children, bilateral
Syndromes associated with pheochromocytoma
MEN 2A, 2B
Von Hippel-Lindau
Neurofibromatosis
Causes of congenital hypothyroidism
Dysgenesis (75%), enzyme defects (10%), transient (10%), HPT axis (5%)
Only 2% have goiter!
Diagnosis of Hashimoto’s thyroiditis
anti-microsomal Ab’s
Diagnosis of euthyroid sick syndrome
low T4, T3, TSH
% of thyroid nodules that are malignant
33%
Iodine scan findings
Graves - high update, subacute thyroidisits - low uptake
Linear growth rate (after 3 years)
5-7 cm/yr
GH therapy side effects
pseudotumor, SCFE, rapid growth of nevi, worsening scoliosis
Diagnosis of GH deficiency
low IGF-1
Pubertal progression (girls)
Breast (8-13)
Pubic hair (8-14)
Growth spurt (10-14)
Menarche (10-16)
Pubertal progression (boys)
Growth of testes (10-17) Penis lengthens (11-15) Pubic hair (11-14) Growth spurt (12-17)
LH function
Men - stimulates Leydig cell to produce testosterone
Women - ovulation
FSH function
Stimulates Sertoli cell to produce inhibin
Women - initiates follicular development
Both - stimulates maturation of germ cells
Testosterone production
Testes (Leydig cells), ovaries, adrenal gland
Estrogen production
Granulosa cells of the ovary
Stimulation of FSH/LH
GnRH from hypothalamus
Pubertal delay
Boys - 14 yo
Girls -13 yo
Most common cause of pubertal delay in boys
Constitutional delay
Constitutional delay of puberty findings
Delayed bone age, testes < 4 mL and penis < 7 cm, positive family history
Kallman syndrome
Hypogonadotropic hypogonadism (delayed puberty, micropenis, cryptorchidism) Anosmia
Swyer syndrome
46 XY but female phenotype due to mutation of SRY gene
Swyer syndrome presentation
Tall women with primary amenorrhea. U/S with normal female internal anatomy. Streak gonads
Premature puberty definition
Boys < 9 yo
Girls < 8 yo
Precious puberty findings
Bone age > chronological age
Causes of precocious puberty
Hypothalamic hamartoma, CAH, ovarian cyst, McCune-Albright, adrenal tumors
Premature thelarche age
bimodal (< 2 yo and > 6 yo)
McCune-Albright Syndrome
cafe-au-lait macules, fibrous dysplasia of bone, peripheral precocious puberty
Vitamin D forms
D3 formed in skin
25-D3 in liver
1,25-D3 in kidney (stimulates intestinal absorption of Ca)
PTH function
Stimulated by drop in iCa
Causes Ca mobilization from bones, increased vit D production, decreased PO4 absorption
Rickets findings
tetany, growth retardation, frontal bossing, rachitic rosary, widening of wrists
X-ray findings in Rickets
widening and fraying of epiphyses
Causes of Rickets
Vitamin-D deficiency
Vitamin-D dependent
Hypophosphatemic (vitamin-D resistant)
Renal failure
Causes of vitamin D deficiency
Lack of sunlight, vitamin D, phenobarb, malabsorbtion
Hypophosphatemic rickets cause
phosphate leak in the proximal tubule
Findings of renal failure rickets
Elevated PO4 (failure of vitamin D and PTH systems)
MEN type 1
Hyperparathyroidism, pancreas islet cell tumor, pituitary tumors
Findings of vitamin D deficiency
Low/normal Ca, PO4, elevated AP, PTH
Most common cause of acquired adrenal insufficiency
Autoimmune adrenalitis
2nd most common cause of CAH
11-hydroxylase deficiency
11-hydroxylase deficiency findings
virilization, HTN, hypokalemia
CAH genetics
AR
MEN type 2A
Pheochromocytoma, hyperparathyroidism, medullary cell thyroid cancer
MEN type 2B
Pheochromocytoma, medullary cell thyroid cancer, mucosal neuromas
Rate of congenital hypothyroidism
1 in 4000 births
Factors associated with decreased IQ in congenital hypothyroidism
Low T4 at birth, delayed bone age at birth, delayed treatment, low T4 during first year of therapy
Pseudohypoparathyroidism
Genetic resistance to PTH (low Ca, high PO4 and PTH)
Pseudohypoparathyroidism findings
Round facies, spade-like hands, short stature, DD
Causes of hyperparathyroidism
Sarcoidosis, immobilization, Vit D intoxication, cancer, Williams syndrome
Familial hypocalciuric hypercalcemia genetics
AD
Familial short stature findings
Bone age = chronological age, normal onset of puberty
Tumor associated with GH deficiency
craniopharyngioma
Diagnosis of Cushing syndrome
urinary free cortisol
Most common cause of Cushing syndrome in infants
adrenocortical tumor
Septo-optic dysplasia findings
panhypopituitarism, hypoplastic optic discs, microphallus (boys)
Treatment of choice for Grave’s disease
Methimazole
Pubertal trigger
pulsatile release of GnRH
Premature adrenarche onset
6 to 8 years
Premature adrenarche management
follow-up every 4-6 months to confirm non-progressive nature
CNS lesion causing central precocious puberty
hypothalamic hamartoma (benign - no resection), septo-optic dysplasia, neurofibroma
Causes of peripheral precocious puberty
CAH, McCune-Albright, severe primary hypothyroidism, adrenal tumor
PE findings of estrogen stimulated vaginal mucosa
pinkish (glistening red = non-estrogen stimulated)
Areolar breast mounding - Tanner Stage
IV
Androgenic changes
body odor, body hair, acne
Gynecomastia seen during what Tanner Stage
II/III
1st sign of puberty in boys
testicular enlargement (4 cc!)
Diagnosis of PCOS
amenorrhea/oligomenorrhea, elevated serum androgen/hirusitism/acne, polycystic ovaries on U/S
Mid-parental height calculation
(maternal height + paternal height +/- 5 in)/2