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Question 490
Endocrinology → General
Classification
Question
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An adult is investigated for suspected growth hormone excess. Which physiological relationship forms the basis of the diagnostic test used to demonstrate inappropriate growth hormone secretion?
Question Stem
Select the single best answer.
Options
A
Growth hormone should rise after an oral glucose load
B
Growth hormone should be unaffected by circulating glucose
C
Growth hormone should be suppressed after an oral glucose load
D
Growth hormone should fall during hypoglycaemia
E
Growth hormone should be completely suppressed during sleep
Explanation
Glucose suppresses growth hormone secretion. Acromegaly can therefore be diagnosed by failure of growth hormone suppression following an oral glucose tolerance test. Conversely, falling blood glucose stimulates growth hormone secretion, a relationship also used in assessment of pituitary function.
Option Validity
A) Glucose normally suppresses rather than stimulates growth hormone secretion.
B) Growth hormone secretion is influenced by blood glucose concentration.
D) Falling blood glucose stimulates growth hormone secretion rather than suppressing it.
E) Growth hormone secretion characteristically surges during sleep.
Further Reading
Saxena, MRCOG-1 Basic Sciences, Endocrinology: Growth Hormone, pp. 304–305.