Chem Path Other

Question 1

Serum Ca in liver failure?

Answer 1

Lower due to failed albumin synthesis

Question 2

Corrected calcium equation and importance

Answer 2

Active Ca may be different from total serum due to conditions such as hypoalbuminaemia, as 40% is bound to albumin.

Question 3

PTH action

Answer 3

Increased osteoclast activity
Gut absorption
Renal resorption
Renal 1 alpha hydroxylase activation

More phosphate excretion (phosphate trashing hormone)

Question 4

1 alpha hydroxylase

Answer 4

Rate limiting enzyme

Increases 1,25(OH)2 vitamin D

Question 5

Vitamin D action

Answer 5

Increases calcium absorption in gut

Question 6

Why does sarcoidosis cause hypercalcaemia?

Answer 6

Sarcoid tissue can express 1-alpha-hydroxylase

Question 7

Which form of vitamin d is prescribed to patients who can’t produce endogenous PTH?

Answer 7

Calcitriol (1,25 hydroxyD3)

Question 8

Why can hypomagnesaemia cause hypocalcaemia?

Answer 8

Magnesium is important in the production of PTH

Question 9

Looser’s zones

Answer 9

Pseudofractures seen in osteomalacia due to increased bone turnover to increase serum Ca levels

Question 10

Rickets Presentation

Answer 10

Bowed Legs
Costochondral Swelling
Widened epiphyses at wrists
Myopathy

Question 11

Which food can cause rickets?

Answer 11

Chappatis due to presence of phytic acid, which chelates vit d in the gut

Question 12

Which receptor does ADH act upon in the kidney

Answer 12

V2 in collecting duct = aquaporin 2 = water resorption

Question 13

Which vascular receptor does ADh act upon

Answer 13

V1 -> peripheral vasoconstriction

Question 14

Signs of hypovolaemia

Answer 14

*low urine sodium (<20) 
dry membranes
postural hypotension 
skin turgor 
reduced urine output

Question 15

How does hypovolaemia lead to hyponatraemia

Answer 15

Low CO = low baroreceptor stimulation = more adh = more water = lower sodium concentration

Question 16

Aldosterone hyponatraemia

Answer 16

reduced na/water absorption