Usefulness of synthetic phospholipid in measurement of activated partial thromboplastin time: a new preparation procedure to reduce batch difference.

Commercial activated partial thromboplastin time (APTT) reagents prepared with phospholipid extracted from animal or plant sources often differ in their response to heparin and coagulation factors and in their reference values. It is also known that there are variations in phospholipid composition and preparation procedure. The present study attempted to demonstrate that an APTT reagent based on synthetic phospholipids (phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine), which are substances of high purity and homogeneity, reduces batch-to-batch difference when compared with two traditional APTT reagents derived from rabbit brain and soybean. Three types of APTT reagent (SYN-APTT, RBT-APTT, SOY-APTT), prepared respectively from synthetic phospholipid, rabbit brain, and soybean, were tested. The total batch-to-batch difference was coefficient of variation (CV) 0.7-2.4% in the five reagents prepared from synthetic phospholipid (SYN-APTT), but CV 1.5-10.3% in the two traditional reagents (RBT-APTT and SOY-APTT). Additionally, high-performance liquid chromatography (HPLC) analysis showed clear variation in the phospholipid composition of the RBT-APTT and SOY-APTT reagents. In conclusion, the SYN-APTT reagent derived from synthetic phospholipid was shown to reduce batch-to-batch difference, and we therefore suggest that synthetic phospholipid is a substance useful in the preparation of APTT reagent and could contribute to stability of supply and uniform diagnosis.