Endocrinology

Question 1

Most URGENT work up to obtain for ambiguous genitalia?

Answer 1

Electrolytes - think CAH because of decompensation risk

Question 2

How are calcium, magnesium and phosphorous transported across the placenta?

Answer 2

A COW carries the 3 across the placenta via ACTIVE transport.

Question 3

What is the cut off level for TSH to treat for hypothyroid?

Answer 3

> 40

Question 4

MCC of neonatal hypothyroidism

Answer 4

Ectopic thyroid (dysgenesis)

Question 5

Goal of orchipexy if undescended testes?

Answer 5

Increase sertoli cells, increase germ cells and increase testicular volume. Reduce risk of testicular cancer

Question 6

When does anatomic development of the thyroid gland begin?

Answer 6

3 weeks

Question 7

Where does the thyroid gland form from?

Answer 7

Midline endodermal thickening in the primitive pharyngeal floor at 5-7 weeks

Question 8

When does the fetal thyroid gland start secreting thyroid hormones?

Answer 8

12 weeks

Question 9

When does the TSH surge occur and what is it in response to? When do levels decrease?

Answer 9

Peaks at 30 min age, due to extrauterine cold exposure

Levels decrease over 1-2 weeks postnatally

Question 10

When does the T4 surge occur and what is it in response to? When do levels decrease?

Answer 10

Peaks at 24-36 hours after birth, in response to TSH surge.

Levels decrease over 1-2 weeks (follows TSH)

Question 11

When does the T3 surge occur and why?

Answer 11

Peaks at 24-36 hours after birth due to neonate’s increased ability to convert T4 to T3.

Question 12

How much do the thyroid hormones cross placenta:
TRH
TSH
T4 and T3

Answer 12

TRH is produced in small amounts during pregnancy and crosses the placenta
TSH does NOT cross the placenta
Placenta partially degrades T3 and T4 (partially permeable), reverse T3 is in the highest concentration in the fetus

Question 13

Most common cause of congenital hypothyroidism?

Answer 13

Primary -> permanent type due to thyroid dysgenesis. Ectopic thyroid most common

Question 14

Features of Pendred syndrome?

Answer 14

Autosomal recessive
CN 8 deafness
Thyroid hormone dysgenesis

Question 15

How is glucose transported across the placenta?

Answer 15

Facilitated diffusion using glucose transporters

Question 16

What are the 4 main substrates for gluconeogenesis??

Answer 16

1. Lactate/pyruvate
2. Gluconeogenic amino acids (alanine most important)
3. Glycerol
4. Propionic acid

Question 17

When does glycogen storage occur in the liver?

Answer 17

During 3rd trimester

Question 18

Which thyroid hormone does NOT cross the placenta?

Answer 18

TSH

Question 19

Which hormones are produced in the anterior pituitary?

Answer 19

GH, TSH, ACTH, LH, FSH and prolactin

Question 20

Which hormones are produced in the posterior pituitary?

Answer 20

Oxytocin and ADH

Question 21

Which hormone promotes calcium and phos deposition in the fetus?

Answer 21

Maternal estrogen

Because of fetal high calcium, the fetal PTH is suppressed

Question 22

Physiologically active form of calcium?

Answer 22

iCal

Tightly regulated by an interaction of PTH and 1,25-OH-D

Question 23

For an infant born to a mother with Graves, when should TSH and fT4 levels be obtained?

Answer 23

3-5 days of age, repeat at 10-14 days

Question 24

Which hormone needs to be tested with infantile hemagiomas and why?

Answer 24

Thyroid

Infantile hemangiomas undergo consumptive hypothyroidism during their proliferative phase

Question 25

Cause of hypercalcemia in subcutaneous fat nodule

Answer 25

unregulated increase in the extrarenal release of 1,25-dihydroxy vitamin D during necrosis of granulomatous fat cells, leading to an increased intestinal absorption of calcium.