Erythrocytosis as a cause of false increase in prothrombin time and activated partial thromboplastin time.

Editor: Prothrombin time (PT) as an index of liver dysfunction is well-established. Abnormal PT in a patient with acute hepatitis alerts us to the possibility of impending liver failure and mandates much closer monitoring. We present a case where PT was falsely elevated. A 23-year-old gentleman, with ventricular septal defect, severe pulmonary hypertension, and reversal of shunt, was referred for opinion on deranged liver function. He had no jaundice, prodrome, ascites, or signs of liver decompensation. On examination, his vital parameters were normal. There was clubbing and cyanosis with normal neck veins. Abdominal examination showed no organomegaly or free fluid. He was on digoxin and diuretics and was not anticoagulated. He had erythrocytosis [hemoglobin of 23.3 g/dL (mean corpuscular volume, 92.6 fL; packed cell volume, 74 %)] with normal total white blood cell and platelet counts. He had mild indirect hyperbilirubinemia (serum total bilirubin, 1.6 mg/dL; direct fraction, 0.3 mg/dL), mildly elevated liver enzymes (serum alanine aminotransferase, 75 U/L; serum aspartate aminotransferase, 57 U/L), and normal serum albumin (5 g/dL). His PT was prolonged, 26.3 s, i.e. 14 s above the normal upper limit with an international normalized ratio (INR) of 2.37. Activated partial thromboplastin time (aPTT) was also prolonged, 58.9 s, i.e. 19 s above the normal upper limit. The PT and aPTT values were repeated on two different occasions with similar results. Etiological evaluation of liver disease, in the form of HBsAg, HCV antibody, serum ceruloplasmin, and serum ferritin, was unyielding. His liver on ultrasound appeared normal. The presence of coagulopathy was the only factor alarming in what looked like a nonspecific liver function abnormality. The tests were repeated on the same day after adding excess blood (7 mL) to the same amount of citrate thus maintaining the normal bloodto-anticoagulant ratio (Table 1). The corrected PT and aPTT were 11.6 s (INR, 1.08) and 29.4 s, respectively. The patient was reassured at that point and asked to review later. The patient was unable to come for reassessment, but on telephonic follow up at 6 months from the initial visit, he remained well and anicteric.