--- title: "What does a low IGF-1 mean?" type: biomarker-interpretation url: "https://www.test-well.com/biomarkers/igf-1/low" biomarker: IGF-1 direction: low reference_range: - "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" reviewed_at: 2026-09-08 review_status: reviewed date_published: 2026-09-05 --- # What does a low IGF-1 mean? > 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. ## 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. ## What are the common causes of low IGF-1? 1. Aging (expected decline; bands are age-specific) 2. Malnutrition, fasting, eating disorders, recent significant weight loss 3. Poorly controlled diabetes, liver disease, kidney disease, hypothyroidism 4. Oral estrogen (raises GH but lowers IGF-1), chronic inflammation 5. Adult GH deficiency: pituitary tumor, surgery, radiation, traumatic brain injury (less common) 6. 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 at TestWell: [TSH (Thyroid Stimulating Hormone)](https://www.test-well.com/tests/tsh) ($26.99), [TSH + Free T4](https://www.test-well.com/tests/tsh-with-free-t4) ($27.99), [Cortisol (AM)](https://www.test-well.com/tests/cortisol-am) ($26.99), [Estradiol (E2)](https://www.test-well.com/tests/estradiol) ($35.99), [Prolactin](https://www.test-well.com/tests/prolactin) ($39.99), [Free T4 (Thyroxine)](https://www.test-well.com/tests/free-t4-test) ($23.99). ## How do you recheck IGF-1? | Test or panel | Type | Price | Fasting | Results | | --- | --- | --- | --- | --- | | [Men's Hormone Panel](https://www.test-well.com/tests/mens-hormone-panel) | Panel (7 tests) | $199.99 | No | 3–5 business days | | [Men's Cancer Screening Panel](https://www.test-well.com/tests/mens-cancer-screening-panel) | Panel (12 tests) | $299.99 | Yes | 3–5 business days | | [Women's Cancer Screening Panel](https://www.test-well.com/tests/womens-cancer-screening-panel) | Panel (12 tests) | $299.99 | Yes | 3–5 business days | | [IGF-1 (Insulin-like Growth Factor)](https://www.test-well.com/tests/igf-1-test) | Test | $37.99 | No | 3–5 business days | Plus one $6 lab processing fee per order; physician authorization included. ## 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. ## Related - [What does a high IGF-1 mean?](https://www.test-well.com/biomarkers/igf-1/high) - [IGF-1 reference ranges](https://www.test-well.com/biomarkers/igf-1) - [Total Testosterone reference range](https://www.test-well.com/biomarkers/total-testosterone) - [Free Testosterone reference range](https://www.test-well.com/biomarkers/free-testosterone) - [SHBG reference range](https://www.test-well.com/biomarkers/shbg) ## Sources - [Mayo Clinic Labs](https://www.mayocliniclabs.com/test-catalog/overview/8836) - [MedlinePlus (NIH) — IGF-1 (Insulin-like Growth Factor 1) Test](https://medlineplus.gov/lab-tests/igf-1-insulin-like-growth-factor-1-test/) --- Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-08. Review policy: https://www.test-well.com/editorial-policy Canonical page: https://www.test-well.com/biomarkers/igf-1/low Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.