IGF-1 - Insulin-like growth factor 1 (Somatomedin C)
Insulin-like growth factor I is a single polypeptide chain with three intra-molecule disulfide bonds. It consists of 70 amino acid residues with a molecular mass of 7649 daltons.1 It is structurally homologous to IGF-II and insulin. IGF-I circulates primarily in a high molecular weight tertiary complex with IGF-binding protein-3 (IGFBP-3) and acid-labile subunit. In vivo, IGF-I synthesis is stimulated by growth hormone (GH) and nutritional intake.
In humans, plasma IGF-I levels are barely detectable at birth, rise gradually during childhood, peak during mid-puberty until approximately 40 years of age, then decline gradually. Maternal plasma levels increase during pregnancy. In the diagnosis of growth disorders, measurements of IGF-I are a useful indicator of growth hormone (GH) secretion. A normal plasma or serum IGF-I concentration is strong evidence against GH deficiency. A low IGF-I value implies GH deficiency and requires additional testing to determine whether GH secretion is subnormal. Measurement of IGF-I is also useful in assessing change of nutritional status.
Measurement of IGF-I in serum is complicated by the presence of acid-labile components and binding proteins. Acid treatment is necessary to release IGF-I to ensure accurate quantitation.
Lab units Conversion Calculator. Convert IGF-1 - Insulin-like growth factor 1 (Somatomedin C) level to nmol/L, µg/L, µg/dL, µg/100mL, µg%, ng/mL. Clinical laboratory units online conversion from conventional or traditional units to Si units. Table of conversion factors for IGF-1 - Insulin-like growth factor 1 (Somatomedin C).