Modified APTTを用いた妊婦および習慣流産患者におけるループス抗凝血素の測定

抄録

A modification of the activated partial thromboplastin time (mAPTT) test was used to detect lupus anticoagulant (LA). In this mAPTT test, phospholipid reagent was used at 20 times lower concentration than that in the usual APTT test.
The normal range of values for the mAPTT was determined in 191 women in early pregnancy, who had no medical complications and had a history of normal pregnancy. As the mean mAPTT of these women was 59.4 + 10.9 sec., plasma values of above 81.1 sec. (mean + 2SD) was considered abnormally high. Plasma samples with abnormally high mAPTT values were mixed with a equal volume of normal plasma and re-examined. When the value on reexamination was also abnormally higher, the plasma was regarded as LA positive.
The plasma mAPTT values of 704 women in early pregnancy were measured and only one woman (0.14%) was found to be LA positive. In this case intra-uterine fetal death occurred at 21 weeks of pregnancy. She had been considered at high risk of LA because she had SLE.
Nonpregnant women with a history of abortions were also tested. Three (11.6%) of 26 women with a history of repeated abortions and one (3.4%) of 29 women with a history of only 2 abortions were LA positive. One LA-positive patient with a history of repeated abortions was treated with predonine (40mg), aspiris (50mg) and dipyridamole (150mg). Her increased mAPTT value gradually decreased to the normal range. In week 8 of pregnancy, hypertension developed and so the dosage of predonine was decreased. But then the mAPTT value increased again and the fetus died in week 11 of pregnancy.
The modified APTT test is useful for screening for LA and evaluating its level. The LA screening test should be made on high risk patients with a history of repeated abortions, autoimmune diseases eth., but it is not necessary for all pregnant women because the incidence of LA is normally low. An adequate dosage of predonine is necessary for treatment of LA positive pregnant women.