IGFBP-3 ELISA

Enzyme immunoassay for measurement of IGFBP-3 in human serum and heparin plasma for diagnostic and scientific purposes. This ELISA uses highly specific antibodies. No cross reactivity to other components of the IGF system are known and small sample requirement is ideal for use in pediatrics. Advantages of our IBL International total IGFBP-3 ELISA: - Detection limit of 0.1 ng/mL - Single standards: 0.4, 2, 6, 15, 30 ng/mL - Assay-range 0.3 –15150 ng/mL - Intra-Assay variance 4.51% - Inter-Assay variance 6.3% - Broad linear range (1:20 to 1:1280) - 2 internal controls - Fast – incubation time of 2.5 h Insulin-like growth factors (IGF)-I and -II are bound to specific binding proteins (IGFBPs) in the circulation. Today the existence of at least six binding proteins and several related proteins has been shown. The predominating IGFBP in blood is IGFBP-3 which largely determines the total IGF-I and IGF-II concentration. Physiological function of IGFBPs is mainly to regulation of bioavailability of IGF-I and –II. IGFBP-3 is the most abundant IGFBP in human serum. It binds IGF-I with high affinity and is able to form a ternary complex with acid-labile subunit (ALS). IGF bound in this complex is biological inactive. Activation occurs by proteases cleaving ALS and IGFBP-3 specifically. Clinical Relevance For clinical practice, the most important regulatory factor of IGFBP-3 is GH. IGFBP-3 measurements correlate significantly with GH secretion. Slow response to GH and constant circadian levels during chronic daily application of GH suggest that IGFBP-3 reflects the GH secretory state over days. Determination of human IGFBP-3 is done for diagnostic of Growth Hormone deficiency. Serum IGFBP-3 measurements are also suited for evaluating the potential of a patient to respond to GH and for GH therapy monitoring.