This test looks for the existence of IgG antibodies made against kidneys glomerular basement membrane (GBM). Blood leaking into the urine is caused by these antibodies attacking the GBMs capillaries. Anti-GBM glomerulonephritis which occurs when GBM are present together with lung membrane injury is a disorder that is usually associated with kidney damage and is also referred to as Goodpasture syndrome. Insulin-like growth factor (IGF) binding protein-3 (IGFBP-3), one of the six members of the IGFBP family, is a key protein in the IGF pathway. It is the most abundant of a group of IGFBPs that transport, control bioavailability and half-life of the insulin-like growth factors (IGF), in particular IGF-1, the major mediator of the anabolic- and growth-promoting effects of growth hormone (GH). Diagnosing growth disorders It is useful in diagnosing adult growth hormone deficiency, monitoring of recombinant human growth hormone treatment