IGF-1 · low result
What does a low IGF-1 mean?
Short answer
Low IGF-1 most often reflects things other than growth-hormone deficiency: poor nutrition or recent weight loss, uncontrolled diabetes, liver disease, hypothyroidism, chronic illness, high-dose estrogen and simply older age (the reference bands fall by decade). True adult GH deficiency — usually after pituitary surgery, radiation or a tumor — is confirmed with a stimulation test, not IGF-1 alone.
Medically reviewed by Youmna DiStefano, MD · Last reviewed September 2026
What is the normal range for IGF-1?
- age 18–30: 116 – 358 ng/mL
- age 31–50: 94.0 – 252 ng/mL
- age 51–70: 81.0 – 225 ng/mL
- age 71+: 53.0 – 175 ng/mL
Can reflect growth hormone deficiency, malnutrition, or chronic illness.
Full reference table, citations and testing options: IGF-1 biomarker page.
What are the common causes of low IGF-1?
- Aging (expected decline; bands are age-specific)
- Malnutrition, fasting, eating disorders, recent significant weight loss
- Poorly controlled diabetes, liver disease, kidney disease, hypothyroidism
- Oral estrogen (raises GH but lowers IGF-1), chronic inflammation
- Adult GH deficiency: pituitary tumor, surgery, radiation, traumatic brain injury (less common)
- Laron syndrome and other GH insensitivity (rare, childhood)
What symptoms go with low IGF-1?
- Often none
- Low energy, reduced muscle mass and exercise capacity, increased central fat, low mood — nonspecific and shared with many conditions
What do clinicians usually check next?
- Repeat with the same lab; check TSH, A1c, liver panel, nutrition and medications
- If pituitary disease is possible: other pituitary hormones (cortisol, TSH/free T4, testosterone or estradiol, prolactin)
- GH stimulation test (glucagon or macimorelin) through an endocrinologist — the diagnostic step
- Do not start GH or peptides on an IGF-1 value alone
Follow-up tests available at TestWell: TSH (Thyroid Stimulating Hormone) ($26.99), TSH + Free T4 ($27.99), Cortisol (AM) ($26.99), Estradiol (E2) ($35.99), Prolactin ($39.99), Free T4 (Thyroxine) ($23.99).
How do you recheck IGF-1?
Prices are cash-pay; every order adds one $6 lab processing fee. Physician authorization is included; no insurance or referral needed.
| Test or panel | Type | Price | Fasting | Results |
|---|---|---|---|---|
| Men's Hormone Panel | Panel · 7 tests | $199.99 | No | 3–5 business days |
| Men's Cancer Screening Panel | Panel · 12 tests | $299.99 | Yes | 3–5 business days |
| Women's Cancer Screening Panel | Panel · 12 tests | $299.99 | Yes | 3–5 business days |
| IGF-1 (Insulin-like Growth Factor) | Test | $37.99 | No | 3–5 business days |
Common questions
Does low IGF-1 mean I need growth hormone?
No. Low IGF-1 has many non-pituitary causes and normal IGF-1 doesn't exclude deficiency either. GH therapy for adults requires a failed stimulation test plus a structural pituitary cause; it is not prescribed from IGF-1 alone.
Why do IGF-1 ranges drop with age?
GH secretion declines steadily after the 20s, so a 65-year-old's normal is well below a 25-year-old's. Always read the result against the age band, not the overall range.
Educational content, not a diagnosis. Lab results are one input; a clinician interprets them with your history and exam.