Growth Hormone, Stimulation and Suppression Tests


Somatotropic hormone, somatotropin, GH, hGH.

To assess pituitary function and evaluate the amount of secreted growth hormone (GH) to assist in diagnosing diseases such as giantism and dwarfism.

Patient Preparation
The patient should fast and avoid strenuous exercise for 12 hr before specimen collection for stimulation and suppression studies. Some medications may adversely interact with the inducer used for the test, e.g., amphetamine, dextroamphetamine, and methylphenidate interact with clonidine. The requesting HCP should be aware of any potential interacting medications used in the studies and advise restrictions by medical direction. Protocols may vary depending on the type of induction used.

Normal Findings
Method: Immunoassay.

Growth Hormone
AgeConventional UnitsSI Units (Conventional Units × 1)
Cord blood8–40 ng/mL8–40 mcg/L
1 d5–50 ng/mL5–50 mcg/L
1 wk5–25 ng/mL5–25 mcg/L
Child2–10 ng/mL2–10 mcg/L
  Male0–5 ng/mL0–5 mcg/L
  Female0–10 ng/mL0–10 mcg/L
  Male older than 60 yr0–10 ng/mL0–10 mcg/L
  Female older than 60 yr0–14 ng/mL0–14 mcg/L
Stimulation Tests
Rise above baselineGreater than 5 ng/mLGreater than 5 mcg/L
Peak responseGreater than 10 ng/mLGreater than 10 mcg/L
Suppression Tests0–2 ng/mL0–2 mcg/L

Critical Findings and Potential Interventions

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