Platelet activation and prostacyclin supporting capacity in the loin pain hematuria syndrome.

The loin pain hematuria syndrome has been characterized as a constellation of severe recurrent flank pain and hematuria, occurring predominantly in young women. We studied a 17-year-old woman who had recurrent right flank pain, gross hematuria, and fever, without evidence of urinary tract infection. Her physical exam was remarkable for right costovertebral angle tenderness and a normal BP. Her urinalysis showed blood and protein but her creatinine clearance and 24-hour urinary calcium excretion were normal. A kidney biopsy was remarkable for arteriolar subintimal fibrous thickening and fibrin deposition, but no glomerulonephritis. Her peripheral hemostasis evaluation was normal except for circulating platelet aggregates and elevated fibrinopeptide A levels. On two occasions, her serum was unable to normally support prostacyclin (PGI2) production by cultured human umbilical endothelial cells, as measured by radioimmunoassay (RIA) of its stable metabolite 6-keto-PGF alpha. Blood samples from the right renal vein and inferior vena cava revealed a selective elevation of fibrinopeptide A in the right renal venous effluent. The presence of circulating platelet aggregates and elevated levels of fibrinopeptide A (a cleavage product of fibrin) suggests that platelet activation and fibrin deposition may play a role in the pathogenesis of this disorder. The inability of her serum to normally support the production of the potent antiplatelet and antithrombotic substance, PGI2, could represent a primary renovascular endothelial cell defect.