All 3 patients were female. These examples illustrate the utility of RCM and PV determinations in establishing the presence of true erythrocytosis or plasma volume contraction in clinical situations in which this information could not be obtained in any other way. The ET patient was a JAK2 V617F heterozygote with stainable marrow iron, a normal serum ferritin and red cell MCV, and no splenomegaly. The PV patient was having recurrent intra-abdominal venous thrombosis despite therapeutic anticoagulation.

BSA indicates body surface area; and TBV, total blood volume.

*The expected values were derived from the tables in Pearson et al.⁴⁴