Endocrine

Question 1

Timing of newborn screening for congenital hypothyroidism (CH)?

(December 2021)

Answer 1

Recommended after 24 hours of life to avoid the physiologic TSH surge in the first 1-2 days after birth. Preterm neonates have immature H-P-A axis and thus should have theirs repeated at 2 weeks of life vs term corrected

Question 2

Relationship between dopamine and HPA axis/newborn screen

(December 2021)

Answer 2

Dopamine inhibits hormonal release from anterior and intermediate lobes of the pituitary gland ie TSH, GH, and prolactin are decreased. Termination of dopamine drip induces TSH release and thus secretion of T3/T4 but if PKU collected while on dopamine drip, can result in a false negative result with low/normal TSH

Question 3

Symptoms of hypocalcemia

(December 2021)

Answer 3

-hypertonia
-seizures
-jitteriness
-tremors
-lethargy
-poor feeding
-QTc prolongation

Question 4

Transient hyperinsulinemic hypoglycemia: incidence, cause, risk factors, timing, two most common syndrome associations

(December 2021)

Answer 4

~10% of healthy newborns, occurs because of the abrupt stop in transplacental passage of glucose. Risks include prematurity, IUGR, maternal diabetes, LGA/SGA, and perinatal stress. Incomplete Beta-cell regulation so that insulin is not decreased sufficiently in setting of low serum glucose. Usually resolves spontaneously within 1-2 day of delivery. AAP/PES recommend screening at-risk neonates and supplementing for BG<45 between 4-24 HOL (AAP) and BG<50 in first 48 HOL (PES). Most commonly associated syndromes include Beckwith-Wiedemman and Kabuki syndromes

Question 5

Prolonged neonatal hyperinsulinism (PNH) define, risk factors, timing

(December 2021)

Answer 5

Hyperinsulinemic hypoglycemia that persists beyond 2 days in the absence of known genetic or syndromic etiology. Male, SGA, and C-section delivery. Median diagnosis at 13 days and median resolution at ~180 days.

Question 6

Describe fetal homeostasis of calcium and phosphorous

(October 2021)

Answer 6

The primary source of fetal calcium and phosphorous is via active transport across the placenta resulting in higher fetal concentrations compared to maternal. Majority utilized for bone mineralization with lesser amount excreted through the fetal kidney. Secondary source is resorption of minerals excreted in the fetal urine through swallowing of amniotic fluid. The majority of bone mineralization occurs during the 3rd trimester.

Question 7

Describe postnatal transition homeostasis of calcium and phosphorous

(October 2021)

Answer 7

In the fetus, PTH and calcitriol are present but low because of relatively high [ ] of calcium. After birth the placental influx of calcium is stopped and calcium [ ] decreases by 20-30% first 24 HOL. Phos rises 24-48HOL. Drop in calcium leads to PTH increase > calcitriol increase. At birth main source of Ca switches from placenta to intestinal absorption through feedings, at first passive diffusion in premies and term (at first) with transition to calcitriol-assissted active transport with increasing GA.

Question 8

Metabolic Bone Disease of Prematurity (MBD) 2 most sensitive biochemical markers of disease

(September 2021)

Answer 8

Decreased serum phosphorous ( esp < 4.6) or elevated alkaline phosphatase (esp >900)

Question 9

Prenatal and postnatal risk factors for Metabolic Bone Disease of Prematurity

(September 2021)

Answer 9

Prenatal: HTN, GDM, anemia, cocaine use, IUGR

Postnatal: prematurity, LBW, use of meds like diuretics or glucocorticoids, prolonged TPN like in NEC or SBS, delayed or unfortified feeding, arthrogrypossis, OI etc