Analytical goals for coagulation tests based on biological variation

Allowable imprecision and bias reference limits for laboratory data can be calculated based on measurements of biological variation. Although biological variation of clinical chemical data has been reported from many laboratories, there have been few reports of biological variation in coagulation tests. In this study, we calculated the biological variation of 13 coagulation tests in the clinical laboratory of Kyushu University Hospital and determined allowable imprecision and bias limits of variation. The participating subjects were 17 healthy individuals: three males and two females in their 20s, two males and two females in their 30s, one male and four females in their 40s, and two males and one female in their 50s. Monthly measurements were performed before breakfast 12 times from June 2001 to May 2002 and allowable imprecision and bias limits were calculated. Taken together with coefficient of variation of control plasma used in daily laboratory work at the hospital, the allowable imprecision limits of intra-laboratory variation determined in this study appear to be in attainable ranges.