Indication
Investigation of possible acromegaly
Contraindications
Do not carry this out on patients who have diabetes mellitus, during acute illness, after major surgery and if there is short term treatment with drugs known to impair glucose tolerance.
Procedure
The patient should be fasted overnight (clear water allowed) and should not eat, smoke throughout the test.
- Insert an intravenous cannula.
- Wait 30 minutes.
- Take blood for glucose (grey top vial), growth hormone and IGF-1 estimation (red or gold top vials), together with baseline pituitary function tests, LH, FSH, Prolactin, TFTs & cortisol (red top vial).
- Give patient 75g anhydrous glucose in water (113ml Polycal with water to a volume of 250 - 300ml) to drink.
This should be drunk within five minutes.
- Time 0 is when this has been finished.
- Take blood at 30, 60, 90, and 120 minutes after time 0 for glucose and growth hormone estimation.
Normal response - suppression of growth hormone levels to less than 2-4mU/L, often undetectable.
Failure to suppress suggests acromegaly or gigantism but may also be found in severe liver or renal disease, in heroin addicts or patients taking levodopa.
