There was no splenomegaly, his erythropoietin level was normal, and JAK2 V617F gene was unmutated.
Additional tests were performed but failed to confirm the diagnosis of polycythemia vera (PV). The patient never smoked and had normal oxygen saturation and no evidence of lung disease or sleep apnea. The reticulocyte count was 1.72% (reference range, 0.70%-2.40%), absolute count 80 × 10 9 per liter (reference range, 25-115 × 10 9 per liter). He had a normal white blood cell count of 4.5 × 10 9 per liter (reference range, 3.7-11.1 × 10 9 per liter), normal differential and platelet count of 124 × 10 9 per liter (reference range, 140-400 × 10 9 per liter). MCH was 36.3 pg Hb per cell (reference range, 27-31 pg per cell) and MCHC was 33 g Hb per deciliter (reference range, 31-37 g Hb per deciliter). At the time of evaluation, the patient’s RBC distribution width was 12.8% (reference range, 12.0%-16.5%) and mean corpuscular volume (MCV) was elevated at 110 fL (reference range, 80-100 fL). His Hb and Hct levels have fluctuated over a 2-year period from 17.4 to 18.1 g/dL (reference range, 13.0-17.0 g/dL) and from 52.7% to 54.4% (reference range, 39%-51%), correspondingly. 3Ī 79-year-old man with a history of congestive heart failure, atrial fibrillation, bladder cancer, lumbar spondylosis, gout, and depression was referred for evaluation of elevated Hb and Hct ( Table 1). This case report follows the CARE Guidelines. 1 While MCV represents perhaps the most valued index in hematological practice, 2 its exact effects on Hct and Hb levels, especially in polycythemia cases, have long been underappreciated and completely disregarded in clinical practice. Likewise, the RBC indices (RBCI) such as mean corpuscular Hb (MCH, picograms per cell), MCH concentration (MCHC, grams Hb per deciliter), and, especially, mean corpuscular volume (MCV) that defines the size (volume) of RBCs have been equally important in anemia assessment. The hemoglobin (Hb), hematocrit (Hct), and red blood cells (RBCs) have been historically essential in morphologic classification and diagnosis of anemias. In contrast, the importance of MCV assessment in patients with elevated hemoglobin and hematocrit is not nearly as appreciated.Ĭase Presentation: This case describes a patient who exhibited long-standing macrocytosis (elevated MCV) that contributed to elevated hemoglobin and hematocrit levels thus mimicking a diagnosis of polycythemia vera.Ĭonclusion: The case demonstrates that discounting the MCV effect on hemoglobin/hematocrit levels can lead to potential errors in interpretation of blood tests and misdiagnosis. Introduction: The landmark value of mean corpuscular volume (MCV) in the diagnosis and classification of anemias has been established more than a century ago.