Comparison of four leukocyte differential methods with the National Committee for Clinical Laboratory Standards (NCCLS) reference method.

The authors compared four leukocyte differential counting methods with the National Committee for Clinical Laboratory Standards Reference Leukocyte Differential Method H20-T to determine the clinical sensitivity of the methods. The three-part differential performed by the Coulter Counter Model S-Plus IV and the Toa E-5000, when combined with instrument flags and defined laboratory checking limits for red blood cell and platelet values, are safe and efficacious screening methods for the presence of morphologic abnormalities. The Geometric Data Hematrak 590 proved comparable in clinical sensitivity to a random 100-cell eye-count differential.

Evaluation of a heparin assay method using a fluorogenic synthetic peptide substrate for thrombin.

A heparin assay method based on thrombin cleavage of a fluorogenic synthetic peptide has been evaluated in normal subjects, in patients with chronic renal disease on hemodialysis, and in patients with other disorders. The method has satisfactory accuracy, sensitivity, and reproducibility. In contrast to methods commonly used to monitor heparin therapy, it measures heparin directly and is uninfluenced by patient variables such as low antithrombin III.