Normal Reference Ranges
Adult
Varies by age (typically 100 - 300) ng/mL
Pediatric
Varies by age and Tanner stage ng/mL
Clinical Significance
Primary mediator of growth hormone (GH) action. Stable surrogate marker for GH secretion, as GH levels fluctuate widely throughout the day.
Causes of High
- Acromegaly (adults)
- Gigantism (children)
- Pregnancy
Causes of Low
- Growth hormone deficiency
- Malnutrition / anorexia nervosa
- Hypothyroidism
- Severe liver disease