PCV measurement in the management of polycythaemic patients

Abstract

The PCV of samples from normal individuals and polycythaemic patients being treated by venesection were measured using the microhaematocrit corrected for trapped plasma, radio-isotope dilution, the Coulter 'S' and Coulter 'S Plus'. There was no significant difference between the two manual methods for either the normal individuals or the polycythaemic patients. The Coulter S and S Plus gave lower values for PCV compared with the corrected microhaematocrit, particularly for the polycythaemic patients. The underestimation of the PCV by the Coulter instruments for the polycythaemic group was significantly related to the MCH and MCV. The under-estimation was approximately 6.4% and 7.4% at an MCH of 20 pg by the Coulter S and S Plus respectively. These findings have relevance to the management of polycythaemia by venesection if the effectiveness of treatment is monitored by measuring the PCV by a Coulter instrument.