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Growth Hormone Suppression Testing

Item Value
Approval req'd? No
Available Stat? No
Test code OGT (OGTD, GOTF), NP120, GHB, GH120
Test group GH
Performed by Fasting glucose (GOTF, NP120) Mission Bay, Mount Zion or Parnassus Chemistry
Growth hormone – China Basin Chemistry
In House Availability Glucose (GOTF, NP120): 24 hours per day 7 days per week
Growth Hormone: Sunday or Monday (day shift)
Method Fasting glucose (GOTF) Oxygen consumption (O2 electrode with glucose oxidase)
Growth hormone: Chemiluminescent Immunoassay (Siemens Immulite 2000)
Patient Preparation The patient should be instructed by the care-giver to eat a normal diet containing at least 150 g of carbohydrate and carry out normal physical activity for at least 3 days prior to the morning of the test. An 8-10 hour fast is required before initial baseline sample collection.
Collection Instructions Outpatient testing at ACC available 0730-1400 weekdays, Mission Bay from 0700-1400 and at 2330 Post St. 0800-1400 weekdays.

The patient should be seated for the test and should not smoke.


For patients < 18 years of age, obtain the patient's weight and give the patient 1.75 g of glucose per kg of body weight. If the weight is in pounds, divide by 2.2 to get kg. Do not provide more than 75 g dose regardless of body weight.

If the fasting glucose is 125 mg/dL or higher, glucola will not be given and test will be aborted.
Container type Gray top for fasting glucose (GOTF) and 120 min post glucose (NP120)
Gold top for growth hormone (GHB and GH120)
Amount to Collect 2 mL blood
Sample type Plasma and Serum
Preferred volume 0.5 mL serum and plasma
Min. Volume 0.2 mL serum and plasma
Processing notes Growth hormone (GHB, GH120) Freeze serum at -20C.
Units mg/dL (glucose)
µg/L (growth hormone)
Normal range Growth hormone, baseline

Adult males < 3.1 µg/L
Adult females < 8.1 µg/L


Growth hormone 120 minute post glucose load: <0.4 µg/L

Note: some investigators consider growth hormone suppression test results that are < 0.4 micrograms/L (ng/mL) as normal whereas others consider results < 1.0 micrograms/L (ng/mL) as normal

GH reference range based on measurements in adults.

Growth hormone, baseline reference range was adopted from Siemens Immulite 2000 vendor performed studies and verified in-house by running adult donor samples (excluding autologous donors) on 20 male and 20 female samples.

Glucose reference ranges see lab manual entry for 2 Hour, 75 gram Glucose Tolerance Test, Non-pregnancy
Synonyms GH; HGH; Human growth hormone; Somatotropin
Stability Room temperature 8 hours, refrigerated 2 days (for glucose)
Turn around times Glucose testing available 24 hours per day 7 days per week
Growth hormone: 1-8 days
Additional information Glucose suppression testing: In a disorder suggesting excess GH secretion, draw blood before and during a glucose tolerance test to test for the ability of glucose administration to suppress GH levels. A nadir GH concentration of less than 1 microgram/L after oral administration of glucose has been the historical standard of a normal response, however, a lower nadir GH cut point around 0.4 microgram/L has been recommended to increase sensitivity of detecting modest GH hypersecretion when using contemporary GH assays (American Association of Clinical Endocrinologists medical guidelines for clinical practice for the diagnosis and treatment of acromegaly--2011 update. Katznelson L, Atkinson JL, Cook DM, Ezzat SZ, Hamrahian AH, Miller KK; American Association of Clinical Endocrinologists. Endocr Pract. 2011 Jul-Aug;17 Suppl 4:1-44).

This Siemens Immulite 2000 assay is standardized relative to the 2nd IS 98/574 reference preparation.
CPT coding 82947 x2 (for glucose)
83003 x2 (for growth hormone)
Last Updated 10/13/2016 4:58:46 PM
Entry Number 1767
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