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Question 305
Physiology → Haematology
Classification
Question
SSBAQuestion Header
Which paired change in haematocrit is correct?
Question Stem
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Options
A
Falls after burns; rises after aldosterone
B
Rises after burns; falls after aldosterone
C
Rises after both burns and aldosterone
D
Falls after both burns and aldosterone
E
Remains unchanged after burns but rises after aldosterone
Explanation
haematocrit rises following burns and falls after aldosterone. These changes reflect alterations in the relationship between red-cell volume and plasma volume.
Option Validity
A) This reverses both changes. Burns increase haematocrit, whereas aldosterone lowers it.
C) Aldosterone does not increase haematocrit; it is associated with a fall in haematocrit.
D) Burns are associated with an increased rather than decreased haematocrit. The aldosterone component alone is correct.
E) Haematocrit rises following burns. Burns therefore cannot be regarded as producing no change.
Further Reading
Saxena. Textbook for MRCOG-1. Physiology - Haematology - Haematocrit Value, p.68.