Sickle Cell Anemia: Iron Availability and Nocturnal Oximetry
1London School of Hygiene – Tropical Medicine, London, UK; 2Muhimbili University of Health and Allied Sciences, Dar-es-Salaam, Tanzania; 3Division of Clinical Neurosciences, School of Medicine, University of Southampton, UK; 4Nuffield Dept of Clinical Medicine, University of Oxford, UK; 5University College London - Institute of Child Health, UK
To test the hypothesis that low iron availability, measured as transferrin saturation, is associated with low nocturnal hemoglobin oxygen saturation (SpO2) in children with homozygous sickle cell anemia (SCA; hemoglobin SS).
This was a cross-sectional study of Tanzanian children with SCA who were not receiving regular blood transfusions. Thirty-two children (16 boys) with SCA (mean age 8.0, range 3.6-15.3 years) underwent motion-resistant nocturnal oximetry (Masimo Radical) and had steady state serum transferrin saturation and hematological indices assessed.
Higher transferrin saturation, adjusted for age and α-thalassemia deletion, was associated with lower nocturnal mean SpO2 (p = 0.013, r2 = 0.41), number of SpO2 dips/h > 3% from baseline (p = 0.008, r2 = 0.19) and with min/h with SpO2 < 90% (p = 0.026 r2 = 0.16). Transferrin saturation < 16% (indicative of iron deficiency) was associated with a 2.2% higher nocturnal mean SpO2.
Contrary to our hypothesis, higher iron availability, assessed by transferrin saturation, is associated with nocturnal chronic and intermittent hemoglobin oxygen desaturation in SCA. Whether these associations are causal and are driven by hypoxia-inducible factor and hepcidin-mediated upregulation of demand for iron warrants further investigation.
Cox SE; L'Esperance V; Makani J; Soka D; Prentice AM; Hill CM; Kirkham FJ. Sickle cell anemia: iron availability and nocturnal oximetry. J Clin Sleep Med 2012;8(5):541-545.
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