A human brain thromboplastin standard for distribution in South Africa

As part of an international co-operative study of the International Committee for Standardisation in Haematology, human brain thromboplastins prepared by the acetone-extracted and phenol-saline extraction techniques have been compared as to the yield, the proportion of reagent discarded and wasted, and the sensitivity related to an international standard, the British Comparative Thromboplastin standard (BCT). The phenol-saline extract showed greatly improved sensitivity with greatly reduced batch-to-batch variation as compared with the acetone-dried preparation. In addition, the sensitivity of this reagent conformed to that of the BCT. The implications of the use of such a standardised reagent to the therapeutic management of oral anticoagulant therapy are: (i) standardised, reproducible results; (ii) results comparable with those carried out by other laboratories using a similarly standardised reagent; and (iii) stable therapeutic range.