IGF-1 (Growth Hormone Marker)
Measures insulin-like growth factor 1 to evaluate growth hormone activity and diagnose growth disorders, pituitary conditions, and metabolic imbalances.
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What this test measures
IGF-1 (insulin-like growth factor 1) is a hormone that manages the effects of growth hormone (GH) in the body. Together, IGF-1 and GH promote normal growth of bones and tissues. IGF-1 serves as the major effector of GH-stimulated somatic growth, as well as GH-independent anabolic responses in numerous tissues.
Unlike growth hormone, which changes throughout the day depending on diet and activity levels, IGF-1 levels are more stable, making it a reliable way to track GH activity in the body. IGF-1 provides an indirect but reliable indicator of growth hormone activity, as IGF-1 levels remain relatively stable throughout the day compared to the pulsatile nature of GH. The test is particularly valuable because it reflects average growth hormone function over time rather than just a single moment.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals with unexplained growth concerns in children or adolescents who may be growing too slowly or too rapidly for their age
- Adults experiencing unexplained fatigue, decreased muscle mass, or reduced bone density that could indicate growth hormone deficiency
- Those with suspected pituitary disorders, including potential tumors that could affect growth hormone production
- Individuals being monitored for acromegaly or other growth hormone excess conditions
- Patients undergoing growth hormone replacement therapy who need treatment monitoring
- People with nutritional disorders or chronic illnesses that may affect growth hormone function
What to expect
Preparation
No special preparations are needed for an IGF-1 test. Individuals should inform their healthcare provider about any medications or supplements they're taking, particularly biotin supplements which should be discontinued 72 hours before testing if taking high doses.
Sample Type
A standard blood draw from a vein in the arm using a small needle
Collection
A healthcare professional will take a blood sample from a vein in the arm using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial.
Turnaround
Results are typically available within 2-4 business days after the sample reaches the laboratory
Understanding your results
IGF-1 normal ranges are listed as 2.5th and 97.5th percentile values based on age and sex, with median values also provided. IGF-1 reference values are highly age dependent, and results must always be interpreted within the context of the patient's age. Many laboratories report results with a Z-score, which indicates how many standard deviations a result is above or below the age- and sex-adjusted population mean.
| Population | Reference Range | Notes |
|---|---|---|
| Adults (varies by age) | Approximately 34-548 ng/mL | Ranges vary by lab, assay method, and are often expressed as a Z-score that adjusts for age and sex |
| Z-score interpretation | -2.0 to +2.0 | Results that are within the IGF-1 reference interval will have a Z score between -2.0 and +2.0 |
Reference ranges shown are general guidelines. Your lab report will include the specific reference range used by the laboratory that processed your sample, which is the authoritative range for interpreting your results.
What does a “Low” result mean?
Lower than normal levels of IGF-1 probably indicate growth hormone deficiency or insensitivity to GH. In children, this may be caused by a genetic disorder or brain disease. Low IGF-1 levels: especially when below the age-specific reference range: can point to growth hormone deficiency, GH resistance, malnutrition, or chronic illness. Persons with anorexia or malnutrition have low values of IGF-1, and malnutrition results in low serum IGF-1 concentrations, which recover with restoration of adequate nutrition.
What does a “High” result mean?
Higher than normal levels of IGF-1 may indicate gigantism in children or acromegaly in adults. These conditions are most often caused by a tumor in the pituitary gland. Elevated IGF-1 is often associated with conditions like acromegaly, usually due to excess GH secretion, often caused by a pituitary tumor. High levels may also be associated with other conditions affecting growth hormone production or certain medications that influence IGF-1 levels.
Privacy & confidentiality
All test orders are authorized and results reviewed by an independent, board-certified physician who is not the patient's personal doctor. Your IGF-1 test results are completely confidential and handled with the utmost discretion. Results are <u>not reported to your personal doctor</u> unless you specifically request it, and they are <u>not part of your medical records</u> maintained by your healthcare provider. The test results <u>will not appear on insurance statements or explanation of benefits</u>, ensuring complete privacy regarding your hormone testing. Your employer, insurance company, or any third parties will not have access to your results. This confidential testing allows individuals to understand their growth hormone status privately, with no doctor visit required to order the test. All results are delivered securely and can be shared with healthcare providers at your discretion.
Frequently asked questions
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This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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