Insulin-Like Growth Factor 1 (IGF-1)

What is Insulin-Like Growth Factor 1?

IGF-1 is a hormone produced primarily by the liver in response to growth hormone (GH) stimulation. It mediates many of growth hormone’s effects, promoting cell growth, repair, and regeneration throughout the body. IGF-1 levels are more stable than GH, making it a reliable indicator of growth hormone activity.

Why is it Tested?

Doctors order IGF-1 to evaluate growth hormone disorders, investigate growth abnormalities in children, and assess pituitary function. It’s also used to monitor treatment response in growth hormone deficiency or excess conditions like acromegaly.

Normal Ranges

Reference ranges vary by lab and age. General adult guidelines:

Ages 18–30: 115–358 ng/mL
Ages 31–50: 94–284 ng/mL
Ages 51+: 69–227 ng/mL

IGF-1 naturally declines with age as growth hormone production decreases.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

Low IGF-1

Low levels may indicate:

Growth hormone deficiency
Malnutrition or liver disease
Hypothyroidism
Genetic IGF-1 deficiency

High IGF-1

Elevated IGF-1 levels may suggest:

Acromegaly or gigantism
Pituitary adenoma
Pregnancy (temporary elevation)
Certain medications

How to Track Over Time

IGF-1 provides insight into long-term growth hormone activity and overall anabolic status. Age-related decline is normal, but tracking helps distinguish between healthy aging and pathological deficiency. Monitoring IGF-1 during treatment helps optimize growth hormone therapy dosing.