Question
A patient presents with large sweaty hands, macroglossia, and frontal bossing. What is the best test for confirmation of the diagnosis?
| A. |
GHRH levels
|
| B. |
IGF-1
|
| C. |
IGF-2
|
| D. |
GH levels after glucose suppression
|
Show Answer
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Correct Answer » D
Explanation
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|
The patient has classical features of acromegaly, including:
- Enlarged sweaty hands
- Macroglossia
- Frontal bossing
Acromegaly results from excess Growth Hormone (GH) secretion, usually due to a pituitary somatotroph adenoma.
Diagnosis
- Serum IGF-1 is the best screening test because its levels remain stable throughout the day and reflect integrated GH secretion.
- The gold standard confirmatory test is the Oral Glucose Tolerance Test (OGTT) with measurement of GH levels.
Normally, oral glucose suppresses GH secretion to very low levels. In patients with acromegaly, GH fails to suppress, confirming autonomous GH secretion.
Why the Other Options Are Incorrect
A. Growth Hormone-Releasing Hormone (GHRH) level
- Rarely measured.
- Used only when ectopic GHRH secretion is suspected.
- Not a routine diagnostic or confirmatory test.
B. Serum Insulin-like Growth Factor-1 (IGF-1) level
- Best screening test for acromegaly.
- Elevated IGF-1 strongly suggests the diagnosis but does not confirm it.
- Confirmation requires demonstration of failure of GH suppression after oral glucose.
C. Serum Insulin-like Growth Factor-2 (IGF-2) level
- Not used in the diagnosis of acromegaly.
- Associated with non-islet cell tumor hypoglycemia.
