What is nephrocalcin, and what role does it play in the formation of renal stones?
Nephrocalcin is an anionic protein produced by the proximal renal tubule and Henle’s loop. It usually inhibits the nucleation, crystal growth, and aggregation phases of stone formation. However, nephrocalcin isolated from some stone formers has defective structure and function and is found in the matrix of many calcium stones. Thus, nephrocalcin may have a dual role in stone formation. When normal, it acts as an inhibitor of stone formation. When abnormal, it may serve as a promoter by binding calcium and form a nidus for crystallization.