Endocrinology Flashcards
thyroid hormone starts production at
12 weeks? 18-20 weeks?
11 beta hydroxylase
2nd MCC CAH. Middle Eastern descent. Inability to convert deoxycorticosterone to aldosterone
Inability to convert 11 deoxycortisol to cortisol
Excess of 17 OHP –> increased serum androgen production
No salt wasting (deoxycorticosterone present)
Tx. glucocorticoid replacement, genital reconstruction
MCC congenital heart disease of IDM
TGA
MCC congenital hypothyroidism
thyroid dysgenesis (75%) - partial or complete absence of thyroid
What is pseudohypoparathyroidism
defects in peripheral PTH receptors, hypocalcemia in setting of elevated PTH
Features of Vitamin-D dependent rickets
pathologic fractures, rachitic rosary, moth-eaten metaphyses
Hypoparathyroidism causes
glandular hypoplasia, neonatal glandular suppression as result of maternal hyperparathyroidism, autoimmune parathyroid its, mutations in Ca receptor
Parathyroid hormone actions
stimulates activity of renal 1-alpha-hydroxylase –> increases active form of Vitamin D and indirectly increases intestinal Ca and phosphorus absorption. Increases renal Ca absorption and decreases renal phosphorus absorption
IDM causes what electrolyte disturbances
neonatal hypocalcemia, hypoglycemia, hypomagnesemia
Only ____% of neonates born to women with Grave’s will be clinically affected
1%
There is a TSH _____ after birth with markedly _____ TsH concentration compared to older infants
surge, elevated
T4 is highest in first ____ of life. T3 tends to rise after first ____ and increases during first _____. rT3 _____ postnatally
week
week, month
decreases
IDM mechanism for surfactant deficiency
increased fetal insulin inhibitory action on fibroblast-pneumocyte factor (acts on type 2 alveolar cells to produce surfactant)
Thyroid gland embryogenesis is complete by _____ weeks of gestation. Begins to secrete hormone at ____ weeks
10-12 weeks. 12 weeks
Fetal TSH receptors don’t become responsive to TSH and TRaBs until _____ weeks
20 weeks
Progressive increase in T4 and thyroxine-binding globulin in fetus, as well as increase in free T4 between _____ weeks of gestation
18-36
5-alpha reductase deficiency
AR; limits conversion of testosterone to DHT.
Sx: ambiguous genitalia, appropriately differentiated Wolffian structures, absent Mullerian-derived structures, small phalus, urogenital sinus with perineal hypospadias, blind vaginal pouch
Later in life: progressive virilization with decreased facial hair and small prostates “Testicles at Twelve”
Females: normal
Aromatase deficiency
Prevents conversion of testosterone to estradiol (androstenedione is not ultimately converted to estrone). Affected females have Mullein duct structures and absent Wolffian duct structures, evident by ambiguous genitalia or cliteromegaly. Multicystic ovaries, tall strature, virilization at puberty, delayed bone age
Name the CAH enzymatic disorders
3-beta-hydroxysteroid dehydrogenase deficiency, 17-alpha hydroxyls, 21-hydroxylase, 11-beta hydroxylase
Hyperglycemia in preterm neonate is correlated with?
sepsis. Preterm hyperglycemic infants have glycosuria that is NOT associated with osmotic diuresis
Hyperglycemia in infants often results from insufficient pancreatic insulin secretion in both ____ and _____ infants
preterm and IUGR
Name how high dose IV lipids and lack of enteral feeding cause hyperglycemia
Lipids –> high FFA –> promotes gluconeogenesis
Lack of enteral feeds: diminished incretin (hormone that promotes insulin secretion)
____% of infants with congenital hypothyroidism are asymptomatic at birth
90%. some maternal T4 is transferred across placenta and brain triiodothyronine concentrations are reserved during fetal life
Does iodine deficiency or excess lead to hypothyroidism? What else can cause hypothyroidism?
both! other causes: amiodarone, iodinated contrast agents, topical antiseptic solutions
What inhibits secretion of TSH
dopamine, steroids, caffeine
Surge in TSH is ____ and T4 is ____ in SGA compared to AGA
surge in TSH is higher, T4 is lower in SGA
Which thyroid hormone is dominant in neonatal life
T3
After birth, TSH increases, leading to more T4.
Deiodinase (D1) in placenta and fetal tissues is activated and converts T4 to T3. After birth, then D3 is not presnt, Rt3 is significantly decreased
During critical illness, D1 is decreased, resulting in.
D3 does _____
decreased T4 –> T3 conversion
D3 converts T4 to RT3
Amphoterecin leads to what electrolyte abnormality
hypomagnesemia –> irritability, tremors, muscle weakness, seizures
Hypoplastic genitalia and midline facial abnormalities –>
hypopituitarism
Function of: LH, testosterone, 5-alpha reductase
Lutenizing hormone contributes most to phallic enlargement and testicular descent
Testosterone and MIS –> produced by testis –> stimulate Wolffian duct differentiation and Mullerian duct regression respectively
5 alpha reductase converts testosterone to dihydrotestosterone –> fusion of labioscrotal folds and formation of scrotum and penis
1st trimester testosterone production from leydig cells is driven by
placental hCG
Preferred medication for treatment of pregnant woman with hyperthyroidism?
PTU. MMI leads to fetal anomalies like cutis aplasia, choanal atresia, TEF
TSH peaks at ____ of age
30 min (extrauterine cold)
c______ and c_____ inhibit reabsorption of calcium
corticosteroids and calcitonin
Difference between osteomalacia and osteopenia of prematurity
Osteomalacia - decreased MINERALIZATION, adequate osteoid production; widening of growth plate with fraying; radiolucent bones as a result of demineralization
Osteopenia of prematurity - decreased bone MATRIX bc decreased deposition or increased matrix resorption; no changes in growth plate, tinner bones, fractures
Estrogen has ____ effect on bone growth
anabolic; positively influences mineral accretion in fetus
Aluminimum is _____ for bones
risk factor for osteopenia of prematurity
Thyroid gland develops from what embryonic layer
endodermal thickening
thyroglobulin produced at 8 weeks. fetal thyroid hormone accumulates at 10 weeks, TSH/T4 secreted at 12 weeks
______ and ______ are produced by testis and stimulate wolffian duct differentiation and mullerian duct regression
Testosterone and Mullerian inhibiting substance
Conversion of testosterone to DHT by 5-alpha reductase leads to ________
fusion of labioscrotal folds and formation of scrotum and penis
Wolffian ducts are derived from ______
excretory mesonephros duct
Mullerian duct (______ duct) is derived from coelomic epithelium
paramesonephric
Sexual differentiation begins by ____ weeks and critical period of external virilization is ____ weeks
6-7; 6-12 weeks
How to treat hypercalcemia
2x maintenance and tx with furosemide
Corticosteroids can inhibit calcium reabsorption
Low phosphate formula will lead to increased Ca absorption
Hypospadias, risk factors, causes
incomplete folding or partial closure of urethra in males; 1 in 500
occurs in glans/corona in 50% of caes, sub-coronal or shaft in 30%, scrotum or perineum in 20%
AMA, pre-existing DM, GA < 37 weeks, patenral hx of hypospadias, smoking, pesticides are associated
Testes descend through canal into scrotum at _____
28 weeks
Phenotypically male infant with bilateral non-palpable testes needs ______
abdominal and pelvic US, adrenal hormone and metabolite levels, and a karotype
Development of thyroid gland begins at
3 weeks
Androgen Insensitivity Syndrome
elevated LH, normal FSH, increased testosterone
Aromatase deficiency
inability to convert testosterone to estradiol an androstenedione to estrone; females have mullerian duct structures and absent wolffian duct structures. Female exam has ambiguous genitalia or cliteromegaly
5-alpha reductase
AR, inability to convert testosterone to DHT. Males have ambiguous genitalia, hypospadias, blind vaginal pouch
Females normal
Describe Ca, PTH in first 2 days of life
Calcium levels DECREASE rapidly in first 6 hrs, lowest at 24 hrs; PTH increases during first day and peaks at 48 hrs of life.
11-beta hydroxylase
(cortisol and aldosterone deficiency) –> increase in testosterone production. Needs glucocorticoid replacement and reconstructive surgery
21-alpha
salt-wasting, cortisol and mineralocorticoid deficiency, elevated 17 OHP
