Physiology

Question 1

Drug clearance (ml/min)
a) equation =  (U x V)/P

Answer 1

U = Urine volume in mg/ml
V = Urine concentration in ml/min
P = Plasma concentration in mg/ml

Question 2

Respiratory alkalosis - drug causes

Answer 2

Theophylline, salicylates

Question 3

Hypomagnesaemia and hypocalcaemia

Answer 3

HypoMg impairs PTH secretion, causing hypoCa

Question 4

Porphyria - treatment

Answer 4

Haem arginate

Question 5

Sarcoidosis

- cause of hyperCa

Answer 5

Increased synthesis of activated Vitamin D (1, 25-dihydroxy cholecalciferol)

Question 6

Congenital adrenal hyperplasia

a) 3 types and presentation
b) Most common type
c) Diagnostic test

Answer 6

21-hydroxylase deficiency:

• Salt losing form (75%) - low cortisol/aldosterone (adrenal crisis) and high testosterone (virilisation)
• Non-salt losing form - simple virilisation (high testosterone)
• Non-classical - much milder, not detected at birth, presents with acne/ irregular periods/ abnormal body hair later in life

17a-hydroxylase:

• High aldosterone, hypertension
• Ambiguous genitalia in females

11-Beta hydroxylase deficiency

• Hypertension
• Ambiguous genitalia in females

b) 95% are 21-hydroxylase
c) Serum 17-hydroxyprogesterone - raised in classical CAH