2-Chloro-4-nitrophenyl phosphate

2-Chloro-4-nitrophenyl phosphate is a substrate for an enzyme that hydrolyzes it to produce acid, which in turn reacts with the phenolic group of the substrate to produce an orthophosphate ester. It is used as a marker for bone resorption and has been shown to be increased in women with osteoporosis and in patients with Paget's disease. 2-Chloro-4-nitrophenyl phosphate has also been found useful as a marker of bone turnover in various clinical conditions such as Paget's disease, hyperparathyroidism, or metastatic cancer. This substrate is used with monoclonal antibodies that bind specifically to phosphatase enzymes found on osteoclasts. The enzymatic assay involves incubating the substrate with the antibody and then measuring the amount of phosphate released by the reaction.