title: Mathematical expressions of measuring curves for concentration of clotting factors.
abstract: Conversion of coagulation time (t) to relative arbitrary substance concentration of coagulation factors (II + VII + X) abbreviated c(ra)) was originally made from a measuring curve corresponding to the equation log t = a(o) +a₁ log c(ra). Three more suitable equations are presented and tested for fit: t = A(o) + A₁ c(ra); t = B(o) + B₁ c(ra) + B₂ c²ra; log t = b(o) + b₁ log c(ra) + b₂ log c(ra)². Their suitability for the Simplastin®-A and Thrombotest® methods is also investigated. The last equation yields the best fit and replaces the error-prone reading of log-log curves by a calculation suitable for routine use.
authors.affiliation: Dept. of Clinical Chemistry, Geriatric Unit, De Gamles By, Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Uldall
authors.forename: R
authors.initials: R
authors.lastname: Dybkær
authors.forename: M
authors.initials: M
authors.lastname: Lauritzen
authors.forename: K
authors.initials: K
authors.lastname: Rolighed
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods; D001779:Blood Coagulation Factors / Q000378:metabolism*; D008954:Models, Biological; D010314:Partial Thromboplastin Time; D011517:Prothrombin Time
chemical_list: D001779:Blood Coagulation Factors