An enzyme immunoassay for the quantitative measurement of Insulin-like Growth Factor 1 (IGF-1) in serum.
Insulin-like growth factor I (IGF-1) is a polypeptide of 70 amino acids (7650 daltons), and is one of a number of related insulin-like growth factors present in the circulation. The
molecule shows approximately 50% sequence homology with proinsulin and has a number of biological activities similar to insulin. The peptide is growth hormone (GH) dependent to a high degree, but there is growing evidence of GH-independent secretion. IGF-1 has numerous growth-promoting effects, including mitogenic effects and the promotion of cartilage sulphation. It may also be implicated in the rate of bone turnover. Almost all (>95%) of serum IGF-1 circulates bound to specific IGF binding proteins, of which six classes (IGF-BPs 1 - 6) are now recognized. BP3 is thought to be the major binding protein of IGF-1, forming a ternary complex of 140,000 daltons with IGF-1 and an acid-labile subunit.
The measurement of serum IGF-1 is of recognized value in children with growth disorders and in the diagnosis and monitoring of acromegaly. IGF-1 concentrations change with age, nutritional status, body composition and growth hormone secretion. A single basal IGF-1 determination is useful in the assessment of short stature in children and in nutritional support studies of acutely ill patients. For the diagnosis of acromegaly, a single IGF-1 determination is considered more reliable than a random GH determination.
The DRG IGF-1 600 ELISA Kit is a solid phase enzyme-linked immunosorbent assay (ELISA), based on the principle of competitive binding. Patient samples, standards and controls are acidified and neutralized prior to the assay procedure. The microtiter wells are coated with a monoclonal antibody directed towards an antigenic site on the IGF-1 molecule. The pre-treated sample is incubated at room temperature with Conjugate (biotinylated IGF 1). The wells are washed and then incubated with Enzyme Complex (Streptavidin-HRP-Complex). After addition of the substrate solution, the intensity of color developed is reverse proportional to the concentration of IGF-1 in the patient sample.