Association of ABO blood group with bleeding severity in patients with bleeding of unknown cause

Blood group O has been associated with an increased bleeding tendency due to lower von Willebrand factor (VWF) and factor VIII (FVIII) levels. We explored whether blood group O is independently associated with bleeding severity in patients with mild-to-moderate bleeding of unknown cause (BUC) in the Vienna Bleeding Biobank cohort. Bleeding severity was recorded with the Vicenza bleeding score (BS). Blood group O was overrepresented in 422 patients with BUC compared with its presence in 23 145 healthy blood donors (47.2% vs 37.6%; odds ratio, 1.48; 95% confidence interval [CI], 1.22-1.79). The BS and the number of bleeding symptoms were significantly higher in patients with blood group O than in patients with non-O after adjustment for VWF and FVIII levels and sex (least-square [LS] means of BSs: 6.2; 95% CI, 5.8-6.6 vs 5.3; 4.9-5.7; and of number of symptoms: LS, 3.5; 95% CI, 3.2-3.7 vs 3.0; 2.8-3.2, respectively). Oral mucosal bleeding was more frequent in those with blood group O than in those with other blood types (group non-O; 26.1% vs 14.3%), independent of sex and VWF and FVIII levels, whereas other bleeding symptoms did not differ. Patients with blood group O had increased clot density in comparison with those with blood group non-O, as determined by rotational thromboelastometry and turbidimetric measurement of plasma clot formation. There were no differences in thrombin generation, clot lysis, or platelet function. Our data indicate that blood group O is a risk factor for increased bleeding and bleeding severity in patients with BUC, independent of VWF and FVIII levels.

Turbidimetric measurement of lipase activity--problems and some solutions.

We optimized a commercial turbidimetric method for lipase (EC 3.1.1.3) activity (Boehringer Mannheim Diagnostics) and overcame some of its deficiencies. Increasing the bile salt concentration to 35 mmol/L and the colipase concentration to 6 mg/L and using a continuous recording of the reaction-rate curve greatly improved the reaction kinetics, eliminated false results from increases in absorbance, reduced the lag phase, and increased the analytical sensitivity and accuracy. Differentiation of pancreatitis from nonpancreatitis sera by adding NaCl, 140 mmol/L, to the assay mixture to observe the degree of enzyme activation has important limitations. Sera from patients with pancreatitis and only slight or modest increases in lipase behave like sera from healthy individuals or from patients with nonpancreatic disease. The assay shows no interference by lipoprotein lipase and carboxyl esterase. Results compare well by this optimized method and by an optimized "pH-Stat" titrimetric method.