MONITORING HEPARIN-THERAPY - APTT RESULTS FROM PARTIAL-DRAW VS FULL-DRAW TUBES

Results of the activated partial thromboplastin time (APTT) test can b e influenced by biologic, preanalytic, and analytic variables. When a patient is being treated with unfractionated heparin, the correct inte rpretation of the APTT test result is essential. Laboratories should e valuate all variables influencing this result, particularly when deter mining the ''therapeutic'' range for heparin treatment. This study com pared the APTT results assayed on specimens drawn into 2 different typ es of evacuated blood collection tubes. A statistically significant di fference ws seen in the results when the APTT was outside the referenc e interval, including results in the therapeutic range for unfractiona ted heparin. When the therapeutic range is determined by the laborator y, the evacuated blood collection tube system must be standardized.