A Quantitative Two-Stage Assay for Factor IX (Christmas Factor) Using Plasma from Dogs with Christmas Disease

Summary

A modified 2-stage assay for factor IX which utilizes factor IX deficient plasma plasma from a colony of dogs with Christmas factor deficiency, has been described. The assay is technically less difficult and less time consuming than the established 2-stage assay for factor IX. The assay is more sensitive than other methods currently in use and uses only 4 μl of deficient plasma for a test. Results are comparable to those reported for 1-stage assays, both in vitro and in vivo, with an apparent increase in activity during the conversion of plasma to serum, and with apparently low in vivo recovery of factor IX when infused into a deficient patient.

• References

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