Endocrine

Question 1

Symptoms and signs of adrenal hemorrhage

Answer 1

1. Mild—asymptomatic
2. Moderate—hypertension (induced transient reactive hyperplasia), unconjugated hyperbilirubinemia
3. Severe—hypotensive shock, severe anemia, mass

Risks are difficult delivery (especially if infant large/dystocia) and perinatal depression. (Like other highly vascular areas, is at increased risk from those stresses)

Question 2

Clinical findings in panhypopituitarism

Answer 2

1. hypoglycemia
2. micropenis
3. cholestasis

Question 3

Clinical findings in hypothyroidism

Answer 3

1. hypoglycemia
2. cholestasis
3. failure to thrive

(similar to panhypopituitarism, main difference is sexual development)

Question 4

The system tested by a cortisol stimulation test

Answer 4

Hypothalamic-pituitary-adrenal (HPA) axis

Question 5

Location and stimulants of ADH excretion

Answer 5

Posterior pituitary

Primary stimulant: high serum osmolality (>284 mOsm/kg)

Others: hypoxia, hypotension, acidemia

Question 6

What gene is required for Sertoli cells, and what two hormones do those cells make?

Answer 6

SOX9

Anti-mullerian hormone and mullerian-inhibiting hormone

Sertolis are SOX9 fans and Mullerian-haters

Question 7

What hormone is most responsible for external genitalia development?

Answer 7

Dihydrotestosterone (DHT)

Made from testosterone (via 5-alpha-reductase)

Question 8

Hormone elevated in classic congenital adrenal hyperplasia (CAH)

Answer 8

17-hydroxyprogesterone (17-OHP)

Build-up product from 21-hydroxlyase deficiency (most common form of CAH)

Question 9

Four “basic” laboratory abnormalities in congenital adrenal hyperplasia (CAH)

Answer 9

1. Hyponatremia (salt-wasting from aldosterone insufficiency)
2. Hyperkalemia
3. Metabolic acidosis
4. Hypoglycemia

Question 10

Which would be potentially higher-risk and require “urgent” labs–a maternal history of hyperthyroidism or hypothyroidism

Answer 10

Hyperthyroidism–if mother has Graves disease, antibodies that activate TSH receptors can cross placenta and cause neonatal thyrotoxicosis

(Rare but possibly life-threatening, requires either maternal or cord antibody [TRAb or TSI] titers)

Question 11

What are features of diabetes insipidus, and the main way to distinguish nephrogenic from neurogenic

Answer 11

1. Polydipsia
2. High serum osmolality
3. Low urine osmolality
   * In Neurogenic DI they can’t make ADH, their brain is dumb so ADH doesn’t respond to fluid restriction*

Question 12

Laboratory findings in hypoparathyroidism

Answer 12

Low calcium, high phosphate, low PTH

This last point can help distinguish from pseudohypoparathryoidism

Question 13

Pseudohypoparathyroidism facts

Answer 13

1. Low Ca, high Phos, high PTH (insensitivity)
2. Usually autosomal dominant, see short 4th/5th metacarpals and very round face
3. Associated with inability to respond to TSH as well

Question 14

What hormone is responsible for sexual differentiation in the first trimester (and where does it come from)

Answer 14

hCG from the placenta

(After 12 weeks the fetus’ hypothalamus starts making GnRH that then stimulates LH and FSH from the anterior pituitary)

Question 15

The only thyroid-related compount that canNOT cross the placenta

Answer 15

TSH (thyroid stimulating hormone)

Most of T4 that crosses gets “deactivated” by conversion to rT3

Question 16

The thyroid gland’s derived from what embryonal tissue

Answer 16

Endoderm

As are the lungs and foregut, compared to heart which comes from mesoderm

Question 17

Fetal thyroid starts making thyroglobulin at ___ weeks and secreting thyroid hormone at ___ weeks

Answer 17

8 weeks and 12 weeks

Before 12 weeks, thyroid hormone (T3/T4) comes from mother

Question 18

The thyroid hormone that’s most abundant in the fetus (up until term gestation)

Answer 18

rT3

Majority of maternal T4 is converted to inactive rT3 at placenta by deiodinase (fetus also has deiodinase)

Question 19

What maternal hormone is structurally similar to TSH and responsible for increased maternal T3/T4 production?

Answer 19

bHCG

Whereas placental ESTROGENS are what causes increased production of TBG as well as T3 and T4

Question 20

90% of thyroid hormone secreted by the thyroid is ____

Answer 20

T4

Converted to T3 (more potent, shorter half-life) in peripheral tissues and mainly kept intracellular

Question 21

The most common cause of congenital hypothyroidism

Answer 21

Thyroid disgenesis (75%), i.e. aplasia, hypoplasia or ectopy

Only 10% 2-2 hypothalamic or pituitary issues

Question 22

The best test to confirm thyroid dysgenesis

Answer 22

Radionuclide iodine¹²³ scan “to assess degre of RAIU (radioactive iodine uptake)

Can test TBG, T3, TRH and antithyroid antibodies

Question 23

How long should infants exposed to maternal Graves disease by monitored?

Answer 23

Minimum 4-6 weeks outpatient

• Majority of TSH receptor antibodies are STIMULATING, so will be hypERthyroid*
• Treatment can include PTU or methimazole, beta-blocker and in emergencies corticosteroids*

Question 24

The two parts of the adrenals (cortex and medulla) make which products

Answer 24

CortEX: SEX and other hormones (glucocorticoids, mineralocorticoids)

Medulla: catecholamines (epinephrine, norepinephrine, dopamine)

Question 25

Foremost cause of CAH (congenital adrenal hyperplasia) and lab findings

Answer 25

21-hydroxylase deficiency Hyponatremia, hyperkalemia, VERY elevated 17-OHP, high testosterone *Linked to HLA type/mutations (like DM1 and Celiac)*

Question 26

Secondmost cause of CAH and laboratory findings

Answer 26

11 beta-hydroxylase deficiency Elevated DOC (deoxycortisone) and 11-deoxycortisol, high testosterone *DOC has mineralocorticoid effects so not salt wasting*

Question 27

Hormone products of two testicular cell types

Answer 27

**_S_**ertoli cells: MI**_S_** (regression of Mullerian ducts) **_L_**eydig cells: testosterone and INSL3 (insulin-like growth factor 3) ***_L_**uteinizing hormone, like both factors from **_L_**eydig cells, works on EXTERNAL genitalia* *\*Testosterone also stabilizes Wolffian ducts (internal)\**

Question 28

What should you always test for when you see hypospadias and undescended testes

Answer 28

Congenital adrenal hyperplasia (CAH)

Question 29

What do 5 alpha-reductase and aromatase do?

Answer 29

5 alpha-reductase: testosterone to DHT (dihydrotestosterone, more active form) Aromatase: testosterone to estradiol (and androstenedione to estrone)

Question 30

Two problems that can cause a blind vaginal pouch in 46XY people

Answer 30

5 alpha-reductase deficiency (no DHT) Androgen insensitivity syndrome (AIS) (can't respond to DHT/T)

Question 31

For undescended testes, who ultimately have more orchiopexies--term or preterm males?

Answer 31

TERM males ## Footnote * Frequency of undescended tests is higher in premature infants (don't descend until ~28 weeks)* * 90% in preemies ultimately descend vs. 75% in term*

Question 32

Glucose crosses the placenta via what mechanism?

Answer 32

Facilitated diffusion ## Footnote *"Fetal glucose is maintained entirely by placental transfer...using glucose transporters" (Brodsky 2010).*

Question 33

In what timeframe does glucagon surge after birth?

Answer 33

Minutes to hours ## Footnote *Along with catecholamine surge and insulin down-trend, all in response to being cut off from maternal glucose*

Question 34

"Critical labs" to be drawn when neonates are persistently hypoglycemic (and drawn WHEN hypoglycemic)

Answer 34

When glucose \<40: insulin, growth hormone, cortisol (and PLASMA glucose [i.e. lab-run] since whole blood glucoses are less accurate)

Question 35

The rate of fetal anomalies when diabetic control is achieved *after* conception

Answer 35

7. 8% vs. 2.5% if control's achieved pre-conception

Question 36

Three types of cardiac problems most common in infants of diabetic mothers (IDM)

Answer 36

Hypertrophic cardiomyopathy VSD dTGA

Question 37

The posterior pituitary contains which hormones

Answer 37

Antidiuretic hormone (i.e. vasopressin) Oxytocin *Hypothalamus PRODUCES these, posterior pituitary just stores*

Question 38

The hypothalamic-pituitary axis STARTS production at ___ weeks, but isn't established until ____ weeks

Answer 38

12 weeks (same timeframe as fetal T4 production) 18 weeks is when axis is established (same timeframe as fetal [thyroid] being sufficient)

Question 39

When does T4 peak after birth?

Answer 39

24-36 hours ## Footnote *In response to TSH surge 30min post-delivery (same as glucagon/catecholamine) 2-2 cold stress*