A Simple Method of estimating Prothrombin in Capillary Blood

Abstract

A standard white-blood-cell-counting pipette is used to measure the various ingredients. A soln. of crystalline Na oxalate (13.4 g. per 1.) is drawn into the pipette and one division blown into a clean watch glass. The skin is punctured and blood is drawn up to the 9th division and placed in the watch glass, stirring the oxalate-blood mixture with a glass rod. A freshly prepared snake venom soln. (0.1 mg. dry venom in 1 cc.) up to the 10th div. of the pipette is added to the watch glass mixture. Finally a soln. of anhydrous CaCl2 (2.775 g. per 1.), 10 pipette divs., is added. Within 25-30 sec. timed by a stop watch, visible fibrin formation occurs, seen best against a white background. The test is repeated on a normal subject at the same time. Prothrombin= [image] Repeated estimations on the same patient show a deviation of only 1-2 sec. The white-blood-cell-counting pipette is more readily available than the special micro-hemopipette devised by Kato and the use snake venom obviates preparing a brain extract.