FURTHER EVIDENCE LINKING UROLITHIASIS AND BLOOD-COAGULATION - URINARYPROTHROMBIN FRAGMENT-1 IS PRESENT IN STONE MATRIX

The fact that organic material is always present and distributed throu ghout each renal calculus suggests that it may play a role in stone fo rmation. The organic matrix of calcium oxalate (CaOx) crystals freshly generated in urine in vitro contains urinary prothrombin fragment 1 ( UPTF1) as the principal protein. In this initial study, matrix was ext racted from 12 renal calculi and evaluated for the presence of UPTF1 u sing Western blotting. UPTF1 was present in all eight stones whose pri ncipal component was CaOx, and in one of two stones which consisted ma inly of calcium phosphate (CaP). UPFT1 was absent from the two struvit e calculi examined. The relationship between CaP and UPTF1 was explore d further. Matrix harvested from CaP crystals freshly generated in uri ne in vitro was also shown to contain UPTF1 as its principal component . Our inability to detect UPTF1 in one mixed CaOx/CaP stone may be rel ated to our methods of matrix retrieval, while its absence from two st ruvite stones argues against it being present in the other stones mere ly as a consequence of passive inclusion. This absence may be related to the alkaline environment typical of struvite stone growth. The find ing that UPTF1 is present in some renal stones provides the first dire ct evidence that links blood coagulation proteins with urolithiasis.