Insulin-Like Growth Factor-I ( IGF-I)

IGF‑1 (insulin‑like growth factor 1) is a hormone produced mainly by the liver in response to growth hormone. It stimulates cell growth, bone and muscle development, and tissue repair, and affects glucose metabolism and insulin sensitivity. IGF‑1 levels vary by age; low levels can cause growth failure, while high levels occur in conditions like acromegaly and may be linked to increased cancer risk.

High IGF‑1 usually indicates excess growth hormone (often from a GH‑secreting pituitary tumor) or use of growth‑hormone therapy. It can cause acromegaly signs (enlarged hands/feet, facial change), insulin resistance, joint pain, and raise cardiovascular and certain cancer risks. Elevated IGF‑1 merits endocrine follow‑up—repeat tests, GH suppression testing and pituitary imaging—to identify and treat the underlying cause.

Insulin‑like growth factor (IGF), especially IGF‑1, mediates growth hormone effects by promoting cell proliferation, differentiation and survival. It stimulates bone and muscle growth, tissue repair and protein synthesis, and has anti‑apoptotic actions. IGF also influences glucose and lipid metabolism and plays key roles in fetal development, childhood growth and adult tissue maintenance. Most IGF is produced in the liver in response to growth hormone.

IGF‑1 promotes growth and development by stimulating cell proliferation and differentiation. It supports muscle growth and repair, increases bone density and skeletal health, aids tissue healing, and offers neuroprotective/cognitive support. IGF‑1 also helps regulate metabolism by enhancing glucose uptake and anabolic processes, contributing to recovery after injury and maintaining organ and tissue function.

Normal IGF‑1 levels vary with age and sex. Adults typically fall roughly between 100 and 300 ng/mL (equivalent to µg/L), with much higher values in childhood/adolescence and gradual decline in older age. Laboratories provide age‑specific reference ranges; interpretation should use the lab’s range and consider symptoms and other hormone tests—discuss results with your clinician.

Foods that tend to raise IGF‑1 include animal proteins and dairy—milk, cheese, yogurt and whey—plus red meat, poultry, fish and eggs. High‑protein diets and calorie surplus also increase IGF‑1. Some high‑glycemic or highly processed foods that spike insulin may indirectly raise IGF‑1. Plant proteins (legumes, soy) generally have a smaller effect.