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Review
. 2016:2016:4054806.
doi: 10.1155/2016/4054806. Epub 2016 May 12.

Clinical Scenarios for Discordant Anti-Xa

Jesus Vera-Aguilera  1 , Hindi Yousef  1 , Diego Beltran-Melgarejo  1 , Teng Hugh Teng  2 , Ramos Jan  3 , Mary Mok  1 , Carlos Vera-Aguilera  4 , Eduardo Moreno-Aguilera  5
Affiliations
Review

Clinical Scenarios for Discordant Anti-Xa

Jesus Vera-Aguilera et al. Adv Hematol. 2016.

Abstract

Anti-Xa test measures the activity of heparin against the activity of activated coagulation factor X; significant variability of anti-Xa levels in common clinical scenarios has been observed. Objective. To review the most common clinical settings in which anti-Xa results can be bias. Evidence Review. Guidelines and current literature search: we used PubMed, Medline, Embase, and MEDION, from 2000 to October 2013. Results. Anti-Xa test is widely used; however the assay underestimates heparin concentration in the presence of significant AT deficiency, pregnancy, end stage renal disease, and postthrombolysis and in patients with hyperbilirubinemia; limited published data evaluating the safety and effectiveness of anti-Xa assays for managing UH therapy is available. Conclusions and Relevance. To our knowledge this is the first paper that summarizes the most common causes in which this assay can be affected, several "day to day" clinical scenarios can modify the outcomes, and we concur that these rarely recognized scenarios can be affected by negative outcomes in the daily practice.

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Figures

Figure 1
Figure 1
Coagulation cascade.
Figure 2
Figure 2
Chromogenic anti-Xa method. Factor Xa cleaves the synthetic chromogenic substrate to release a chromophore, quantified by spectrophotometry absorbance. Absorbance is proportional to factor Xa activity and inversely proportional to anti-Xa level.
See this image and copyright information in PMC

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