|Growth Hormone Suppression Test (Glucose Tolerance Test for Acromegaly)|
|Fluoride Oxalate (Grey Top) and|
|Serum (Gold Top)|
|Clinical suspicion of acromegaly or gigantism|
|Target turnaround time|
|1 working day|
|Special requirements & notes|
|Patient is advised to fast for 10-12 hours prior to the test. Small quantities of water are permissible.|
Prepare a solution of glucose to drink – adults are given a 75g anhydrous solution (1.75g/kg body weight if this is being performed on a child). A pre-prepared solution may be available from pharmacy for this purpose.
|The patient should remain at rest throughout the duration of the test.|
Collect a basal sample for growth hormone (gold top) and glucose (grey top)
Ensure the patient drinks the solution within 5 minutes.
Take paired samples (1 gold top, 1 grey top) at 30 minutes, 60 minutes, 90 minutes and 120 minutes after the glucose drink has been consumed.
Send all samples together to the laboratory with one request form for the series. Please indicate the time of sampling on each bottle e.g. 0/30/60/90/120
|Reported as a series of results in conjunction with glucose results. Normal response is to suppress GH production during the test.|
Fasting GH may be normal in 8% of acromegalic subjections, but GH does not suppress to undetectable values during the test.
|5 samples each (4ml) of gold top and grey top – 10 samples in total.|
|If delayed transport to lab, store:|
|Factors affecting result interpretation|
|Contraindicated in patients with diabetes|
GH may fail to suppress due to chronic renal failure, liver failure, active hepatitis, anorexia nervosa, malnutrition, hyperthyroidism, diabetes and adolescence.
|‘Lab Tests Online’ link|
Posted in Assay.
Last updated: July 24, 2019