Description

The Insulin-like Growth Factor 1 (IGF-1) test measures the amount of IGF-1 in your blood. IGF-1 is a hormone produced primarily by the liver in response to growth hormone (GH). It plays a critical role in growth, cell repair, metabolism, and overall tissue health. Because IGF-1 levels remain relatively stable throughout the day, measuring it provides a reliable reflection of growth hormone activity.

Why the Test Is Ordered

  • Evaluate growth disorders in children: Helps identify growth hormone deficiency (short stature, delayed growth) or growth hormone excess (accelerated growth, gigantism).
  • Diagnose or monitor acromegaly: In adults, IGF-1 levels are useful for identifying excess growth hormone, often caused by a pituitary tumor.
  • Monitor growth hormone therapy: Ensures treatment effectiveness and adjusts dosing for children or adults receiving therapy.
  • Assess pituitary gland function: Abnormal IGF-1 levels may indicate pituitary dysfunction, liver disease, malnutrition, or chronic illness.

Symptoms or Conditions That May Prompt Testing

  • Children: slowed growth, delayed puberty, unusually tall stature, or rapid growth.
  • Adults: enlarged hands, feet, or facial features; joint pain; fatigue; reduced muscle mass; abnormal fat distribution.
  • Suspected pituitary disorders or tumors.
  • Monitoring hormone therapy effectiveness.

How the Test Works

  • A blood sample is drawn and analyzed for IGF-1 concentration.
  • Unlike growth hormone, IGF-1 levels are stable throughout the day, so timing is less critical than with a growth hormone test.
  • The test may be ordered alongside other hormone or pituitary function tests to get a full picture of endocrine health.

Interpretation of Results

  • Low IGF-1 levels may indicate:
  • Growth hormone deficiency
  • Chronic illness or malnutrition
  • Liver disease
  • Hypopituitarism
  • High IGF-1 levels may indicate:
  • Growth hormone excess or acromegaly
  • Pituitary adenoma
  • Rare conditions causing elevated growth hormone

Fasting Requirements

  • Fasting is not required, making the test convenient and easy to schedule.

This test provides a key insight into growth hormone activity and overall endocrine health, supporting the diagnosis and monitoring of growth and pituitary disorders in both children and adults.