The DetectX^® RBP High Sensitivity ELISA Kit (formerly named Urinary RBP EIA Kit) is designed to measure RBP levels in urine and dried blood spots. This kit uses a native human RBP molecule as a standard. Standards or diluted samples are added to a coated microtiter plate along with a RBP-peroxidase conjugate and the binding reaction initiated by addition of a RBP-specific rabbit antibody. After a 60-minute incubation, the plate is washed and TMB substrate solution added. After 30 minutes the intensity of the generated signal is read at 450nm.

Retinol binding protein (RBP) is from a family of structurally related proteins that bind small hydrophobic molecules such as bile pigments, steroids, odorants, etc. RBP is a 21 kDa highly conserved, single-chain glycoprotein, consisting of 182 amino acids with 3 disulfide bonds, that has a hydrophobic pocket which binds retinol. RBP has been shown to be a useful marker for renal function as it is totally filtered by the glomeruli and reabsorbed by proximal tubules. This has made RBP a tool to study renal function in heart or kidney transplant recipients, type 1 and 2 diabetics, and in people exposed to uranium from mining operations. Measurement of RBP levels has also been useful in detection and characterization of diseases including hypertension and certain cancers, among other conditions.