Endocrinology

Question 1

Which form of congenital hypothyroidism is likely to be missed on newborn screening?

Answer 1

• Secondary to pituitary or hypothalamic dysfunction (rare).
• Newborn screening checks for elevated TSH seen in primary hypothyroidism.
• In hypopitutiarism and hypothalamic dysfunction TSH will be low and hence not discovered.

Question 2

What suppresses inappropriately high growth hormone?

Answer 2

• Glucose.
• Bromocriptine.
• Somatostatin.

Question 3

What suppresses high levels of prolactin?

Answer 3

• Bromocriptine.

Question 4

What suppresses high levels of cortisol?

Answer 4

• Dexamethasone.

Question 5

What stimulates a low level of growth hormone?

Answer 5

• Insulin.
• Glucagon.
• Exercise.
• Arginine.
• Clonidine.
• L-dopa.

Question 6

What stimulates low levels of LH and FSH?

Answer 6

• GnRH.

- Clomiphene.

Question 7

What stimulates low levels of cortisol?

Answer 7

• Insulin.
• Glucagon.
• ACTH.
• Vasopressin.

Question 8

What stimulates low levels of ADH?

Answer 8

• Water deprovation test.

Question 9

What stimulates low levels of TSH?

Answer 9

• TRH.

Question 10

What is the hallmark of hypophosphatasia?

Answer 10

• Low ALP.

Question 11

What is the effect of hypomagnesemia on PTH?

Answer 11

• Mg <0.5mmol/L PTH release is impaired by parathyroid gland.
• Due to blunting of tissue response to PTH leading to secondary hypocalcaemia.

Question 12

What are features of 21-hydroxylase deficiency?

Answer 12

• Classic CAH.
• 90% of CAH cases.
• Classic “salt wasting” have decreased levels of both glucocorticoid and mineralocorticoid.
• Non-salt wasting disease able to produce enough aldosesterone but have elevated androgens of adrenal origin.
• Females have ambiguous genitalia, males normal.
• Post-natal virulisation in males and females.

Question 13

What are features if 3 beta hydroxysteroid deficiency?

Answer 13

• <2% of CAH patients.
• Required for conversion of 5 steroids to 4 steroids.
• Deficiency results in decreased levels of cortisol, aldosterone and androstenedione but increased DHEA.
• Prone to salt wasting crisis.
• Lack of andostenedione and testosterone leads to incompletely virilised males.
• Elevated DHEA (androgen) means girls are mildly virilised.

Question 14

What are the features of lipoid adrenal hypoplasia?

Answer 14

• Rare, most frequent in Japan.
• Marked accumulation of cholesterol and lipids in the adrenal cortex nd gonads.
• Prenatal death of adrenal and testes tissues duet to cytotoxic effects of choleterol.
• Males are phentypically female but with palpable gonads.

Question 15

What are features of 11 hydroxylase deficiency?

Answer 15

• 5% of adrenal hyperplasia.
• Cortisol is not synthesised adequately but aldosterone production is normal.
• Some corticosterone is produced - it is unusual to manifest signs of adrenal insufficiency.
• Often hypertensive.
• Ambiguous genitalia in females.