The anti-Xa assay is becoming more readily available in community hospital labs. Its potential value in dosing low molecular weight heparins in special situations such as pregnancy, morbid obesity and renal disease is well known. Less well known is a potential role in monitoring unfractionated heparin. How does it compare with PTT monitoring and what are the practical aspects? These questions are answered in a recent review in Lab Medicine, available as free full text here.
The concluding paragraph of the paper summarizes the current controversy:
Anti-Xa assays represent an attractive alternative to the PTT for UH monitoring; however, minimal outcomes data and greater expense are limiting factors. While the cost of Anti-Xa assays might decrease with higher test volumes, prospective clinical outcomes data are not likely to be forthcoming because of the waning utilization of UH. Nonetheless, laboratories may elect to switch to anti-Xa heparin monitoring based on the outcomes data currently available.
