The present invention relates to human Corpuscles of Stannius polypeptides and DNA (RNA) encoding such polypeptides. Also provided is a procedure for producing such polypeptides by recombinant techniques and antagonists against such polypeptides. Human Corpuscles of Stannius protein inhibits calcium uptake and reduces renal excretion of phosphate. Also provided is a diagnostic assay to detect mutations in the nucleic acid sequence encoding the polypeptide and for altered concentrations of the polypeptide in a sample derived from a host.