Table of Contents
ISRN Hematology
Volume 2013 (2013), Article ID 472909, 6 pages
http://dx.doi.org/10.1155/2013/472909
Clinical Study

Hematological and Genetic Predictors of Daytime Hemoglobin Saturation in Tanzanian Children with and without Sickle Cell Anemia

1MRC International Nutrition Group, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
2Muhimbili Wellcome Programme, Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania
3Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7BN, UK
4Department of Psychiatry, University of Oxford, Oxford OX3 7JX, UK
5University College London, Institute of Child Health, London WC1E 6BT, UK

Received 12 February 2013; Accepted 7 March 2013

Academic Editors: D. Lavelle, C. H. Lawrie, and D.-C. Liang

Copyright © 2013 Sharon E. Cox et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Low hemoglobin oxygen saturation (SpO2) is common in Sickle Cell Anemia (SCA) and associated with complications including stroke, although determinants remain unknown. We investigated potential hematological, genetic, and nutritional predictors of daytime SpO2 in Tanzanian children with SCA and compared them with non-SCA controls. Steady-state resting pulse oximetry, full blood count, transferrin saturation, and clinical chemistry were measured. Median daytime SpO2 was 97% (IQ range 94–99%) in SCA (N = 458), lower ( ) than non-SCA (median 99%, IQ range 98–100%; N = 394). Within SCA, associations with SpO2 were observed for hematological variables, transferrin saturation, body-mass-index z-score, hemoglobin F (HbF%), genotypes, and hemolytic markers; mean cell hemoglobin (MCH) explained most variability ( , Adj ). In non-SCA only age correlated with SpO2. -thalassemia 3.7 deletion highly correlated with decreased MCH (Pearson correlation coefficient 0.60, ). In multivariable models, lower SpO2 correlated with higher MCH ( -coefficient 0.32, ) or with decreased copies of -thalassemia 3.7 deletion ( -coefficient 1.1, ), and independently in both models with lower HbF% ( -coefficient 0.15, ) and Glucose-6-Phosphate Dehydrogenase genotype ( -coefficient 1.12, ). This study provides evidence to support the hypothesis that effects on red cell rheology are important in determining SpO2 in children with SCA. Potential mechanisms and implications are discussed.