HGH levels fluctuate throughout the day, so a single measurement isn't always reliable. However, approximate reference ranges are:

Elevated HGH may indicate:
Acromegaly (in adults) / Gigantism (in children):

HGH-Secreting Tumors:

Exercise or Stress:

Hypoglycemia (low blood sugar):

Since HGH helps raise glucose levels, a low blood sugar state triggers its release.

HGH Abuse / Doping:

Low HGH may indicate:
Growth Hormone Deficiency (GHD):

Pituitary or Hypothalamic Disorders:

Aging:

Obesity: