From Dr. Jeanine Walenga, Loyola University Medical Center: George, what could be the reason(s) for a 30 yo female patient having multiple mild factor deficiencies of FIX (64%) and FXII (51%)? The activated partial thromboplastin time (APTT, PTT) was slightly prolonged but corrected with a mixing study. FVIII and FXI were normal. Patient does not have LA or anti-phospholipid antibodies. The best I came up with was that the deficiencies might be due to enhanced excretion from a nephrotic syndrome. Would the double factor deficiencies account for the slightly prolonged APTT? Does the patient have a bleeding risk if going for surgery? Thanks.
Hi, Jeanine, and thank you. I speculate the PTT was prolonged by the XII, and not the IX deficiency, as most PTT reagents are calibrated to prolong at IX levels of 30–40%. Could the apparent IX deficiency actually reflect a mild XII deficiency in your reagent factor IX-deficient (depleted) plasma? It may be the reagent plasma was not validated for XII activity. I’d be inclined to suggest in the absence of bleeding symptoms a factor IX activity level of 64% does not imply a bleeding risk. However, I’m reaching out for help on this one, would like to be sure.
Got this note from Chris Ferrell (same day): Sorry George, I don’t have anything to add. Those values would not be considered deficient with my ranges.