From Barbara Caufield, Good Samaritan Hospital: We adjust the Na citrate volumes in coagulation tubes when the hematocrit (HCT) is > 55%. Do you recommend correcting for low HCTs? Can you tell me what formula you would use for a low HCT? At what HCT percentage do you recommend adjusting the sodium citrate? Thank you!
Hello, Barbara, thank you for this question, and no, there is no requirement for adjusting the sodium citrate volume in anemia even when the HCT is markedly low. This was addressed in the development of CLSI H21-A5, with the decision based on Siegel JE, Swami VK, Glenn P, et al. Effect (or lack of it) of severe anemia on PT and APTT results. Am J Clin Pathol 1998;110:106–10. By the way, I’m curious about how you prepare your tubes for patients with HCTs >55%. I know of one institution that uses a tuberculin syringe to draw out the correct volume, leaving the vacuum intact. I never thought this was possible. Geo.
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