Growth hormone suppression

Specimen:

2 mL blood in a lithium heparin or plain tube.

Method:

Glucose - spectrophotometry. Growth hormone - immunoassay.

Protocol:

Blood is taken prior to a 75 g glucose load and then every 30 minutes for 3 hours.

Reference Interval:

Most sources define adequate suppression as a Growth hormone of <1 mU/L.

Application:

Definitive test for the diagnosis of acromegaly or pituitary gigantism.

IGF-1 is used for initial assessment.

Interpretation:

Failure of growth hormone to suppress indicates autonomous growth hormone release by the anterior pituitary.

Reference:

Simard MF. Neurosurg Clin N Am. 2003; 14(1): 41-54.