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Usefulness of P50,std for the Diagnostic Work-up of Patients with Erythrocytosis
J Lab Med Qual Assur 2018;40:46-49
Published online March 31, 2018
© 2018 Korean Association of External Quality Assessment Service.

Sang-Yong Shin

Department of Laboratory Medicine, Seoul Metropolitan Dongbu Hospital, Seoul, Korea
Correspondence to: Sang-Yong Shin
Department of Laboratory Medicine, Seoul Metropolitan Dongbu Hospital, 124 Muhak-ro Dongdaemun-gu, Seoul 02584, Korea
Tel: +82-2-920-9236
Fax: +82-2-920-9368
E-mail: hypocra@naver.com
Received December 18, 2017; Revised January 18, 2018; Accepted January 22, 2018.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
High oxygen-affinity hemoglobin (Hb) variants and a 2,3-diphosphoglycerate (2,3-DPG) deficiency could cause congenital (familial) erythrocytosis. High oxygen-affinity Hb variants and a 2,3-DPG deficiency might result in low tissue oxygen tension left-shifted oxygen dissociation curves and reduction in the standard P50 value (P50,std, oxygen tension at which haemoglobin is 50% saturated). Hence, the P50,std value is considered while formulating diagnostic strategies for erythrocytosis. In this study, we established a reference range for P50,std using an International Federation of Clinical Chemistry and Laboratory Medicine-approved equation (Hill’s equation) for individual single venous/arterial blood samples. Blood gas analysis results of 243 samples with oxygen saturation ranging from 40%–90% (Hb<16 mg/dL) were selected. The reference range of P50,std was in the 2.5th–97.5th percentile, and was 25.9–27.3 mm Hg. Hill’s equation is a simple approved method for evaluating the P50,std values. Only a single sample of venous or arterial blood and a blood gas analyser are required to obtain the P50,std. Our study provides a useful tool for the diagnostic work-up of patients with erythrocytosis.
Keywords : Hill’s equation, P50, Polycythemia
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