IGF-1 Test: What Your Growth Hormone Marker Means

What Is an IGF-1 Test?

An IGF-1 test measures insulin-like growth factor 1, a hormone made mainly by the liver in response to growth hormone (GH) from the pituitary gland. IGF-1 carries out much of growth hormone work in the body: building bone and muscle in childhood, maintaining tissue in adulthood, and influencing metabolism throughout life. Because growth hormone is released in short pulses, mostly during sleep, a random GH blood draw swings wildly. IGF-1 changes slowly and stays steady through the day, so it serves as the practical window into average growth hormone activity.

The test is a standard blood draw with no special timing. It is used to evaluate growth disorders in children, suspected growth hormone deficiency or excess in adults, and follow-up of pituitary conditions. This guide is educational information, not medical advice, and results must be read against an age-adjusted reference range from your own lab.

When to Test IGF-1

Common reasons to check IGF-1 include:

• Slow growth, short stature, or delayed development in children
• Suspected growth hormone deficiency: persistent fatigue, reduced muscle, increased fat, or low bone density in adults
• Signs of growth hormone excess: enlarged hands, feet, or jaw, coarse facial features, or joint pain
• Follow-up of a known pituitary adenoma or acromegaly treatment
• Unexplained low IGF-1 alongside other pituitary hormone abnormalities
• Baseline testing before growth-related therapy managed by a specialist

IGF-1 is a screening and monitoring tool, not a standalone diagnosis. Abnormal results usually lead to confirmatory testing, such as growth hormone stimulation or suppression tests, arranged through a clinician.

Typical Normal Ranges

IGF-1 ranges depend strongly on age and also vary by sex, assay, and laboratory. Typical approximate bands used by many labs are:

Levels peak in puberty and fall steadily thereafter, so an adult value that looks low against a general range may be perfectly normal for the age bracket. Pregnancy raises IGF-1, while malnutrition, liver disease, and uncontrolled thyroid disorders can lower it. Always confirm your result sits inside the age-adjusted interval on your own report.

What High or Low IGF-1 Means

High IGF-1 suggests excess growth hormone activity. In children, that can mean gigantism with accelerated growth; in adults, whose growth plates have closed, it points toward acromegaly, most often caused by a benign pituitary adenoma. Clues include enlarging hands, feet, and jaw, widening gaps between teeth, joint pain, sleep apnea, and rising blood sugar. Confirmation requires a glucose suppression test and usually pituitary imaging through a specialist.

Low IGF-1 can reflect growth hormone deficiency, which in children shows as slow growth and in adults as fatigue, reduced exercise capacity, unfavorable body composition, and low bone density. But low IGF-1 is not specific: poor nutrition, chronic illness, liver disease, hypothyroidism, and diabetes can all depress it. For that reason, low results are interpreted with symptoms, other pituitary hormones, and often stimulation testing before any conclusion.

How to Order an IGF-1 Test

An endocrinologist or primary care clinician can order IGF-1 during a growth or pituitary workup and arrange confirmatory testing if needed. Through direct-access lab testing, you can order it yourself: select IGF-1 alone or bundled with related hormones or a comprehensive wellness panel, pay online, and visit a local collection site for the draw. No physician order or insurance is required.

No special timing is needed since IGF-1 is stable through the day, though some labs request fasting. List all medicines, supplements, and hormonal therapies on your intake, and note your age clearly so the correct reference interval applies. Results typically post within two to four business days. Share abnormal results with your clinician, since next steps almost always involve specialist evaluation.

How Much Does an IGF-1 Test Cost?

Direct-access IGF-1 testing commonly costs between about $70 and $150 for the single test. Panels that combine IGF-1 with growth hormone, thyroid markers, or broad wellness screening typically range from about $180 to $400.

Clinician-ordered testing billed through insurance depends on your plan and the diagnosis code used. When comparing direct-access options, confirm the collection fee is included, check turnaround time, and verify the lab reports an age-adjusted reference range, which is essential for reading this particular result.