Abnormalities of coagulation in hypertensive patients with reduced creatinine clearance

The prothrombotic state that occurs in uremic patients may increase their cardiovascular risk. We studied hypertensive patients with mild-to-moderate impairment of renal function to determine if they had evidence of abnormalities in the coagulation system.

Renal function was assessed in 382 patients with essential hypertension, in whom 24-hour creatinine clearance, urinary protein excretion, and microalbuminuria were measured. We evaluated the function of the coagulation system by measurement of platelet counts, prothrombin time, partial thromboplastin time, and plasma antithrombin III, fibrinogen, D-dimer, and prothrombin fragment 1 + 2 levels.

Impaired renal function, defined as a creatinine clearance of 30 to 89 mL per minute per 1.73 m(2) of body surface area, was found in 168 (44%) of the patients. Age, blood pressure, duration of hypertension, and plasma levels of fibrinogen, D-dimer, prothrombin fragment 1 + 2, and lipoprotein(a) were significantly greater in these patients than in those with normal renal function; these differences persisted after adjustment for potential confounders. Creatinine clearance was significantly and inversely correlated with levels of plasma fibrinogen (Spearman's rho = -0.26, P <0.001), D-dimer (rho = -0.33, P <0.001), and prothrombin fragment 1 + 2 (rho = -0.20, P <0.001). Levels of plasma fibrinogen (P = 0.009) and D-dimer (P = 0.003) were correlated with renal function independent of age, blood pressure, duration of hypertension, triglyceride level, urinary protein excretion, and erythrocyte sedimentation rate. Lipoprotein(a) levels were correlated with fibrinogen (rho = 0.16, P = 0.003) and D-dimer (rho = 0.26, P <0.001) levels.

Increased plasma levels of fibrinogen, D-dimer, and prothrombin fragment 1 + 2 are present in hypertensive patients with mildly decreased creatinine clearance, suggesting that the coagulation system is activated in these patients.