Determination of Red Cell Indices Cut-off for Identifying Iron Deficiency Anaemia among Pre-school Children with Sickle Cell Anaemia

Os Akodu,Ta Ogunlesi,Fa Adekanmbi

doi:10.46912/jbrcp.145

Abstract

Nigerian pre-school children have a high risk of developing iron deficiency and there is no consistent evidence that patients with sickle cell anaemia are protected from iron deficiency anaemia. The objective is to explore red cell indices cut-off values useful as surrogate for detecting iron deficiency in children with sickle cell anaemia. Ninety-seven children with sickle cell anaemia were recruited from Children Outpatient. Reference intervals were developed using the 2.5th – 97.5th, 3.0rd – 97.0th, 5 – 95th, and 10th – 90th percentile intervals for MCV and MCH. The discriminatory performance of the proposed red cell indices criterion was assessed by use of sensitivity, specificity, accuracy, likelihood ratio and predictive values. The 2.5th, 3rd, 5th, 10th, 90th, 95th, 97th, and 97.5th percentile values were: MCV (62.7, 63.6, 66.5, 69.6, 86.3, 87.7, 89.5, and 90.1fl), and MCH (19.0, 19.5, 20.8, 21.4, 28.2, 29.1, 29.5 and 29.7pg). The various calculated cut-off points for the MCV and MCH had lower sensitivity but a higher specificity for detecting iron deficiency than the standard reference values for the general population. The calculated cut-off point for the study subjects below the 10th percentiles had the best discriminatory performance. The cut-off for iron deficiency was 69.6fl for MCV and 21.4pg for MCH either use singly or in combination. In conclusion, standard reference cut-offs of MCV and MCH based on results from western individuals without sickle cell anaemia of the same age are not in agreement with the estimated values for children with sickle cell anaemia in Nigeria.

Highlights

Sickle cell disease is one of the commonest single gene disorders in man.[1]
The diagnosis of iron deficiency is based primarily on laboratory measurements.conventional tests used, mean corpuscular volume (MCV), transferrin saturation and serum ferritin are limited because of varying ranges of sensitivities and specificities, as they may be modified by conditions other than iron deficiency such as SCD.5,11,12The identification of Iron deficiency anaemia (IDA) in children with SCD is important, as IDA contributes to worsening ofanaemia[5] and may have negative long-term consequences on neurocognitive development13,14. and growth.[15]
The study show marked variation between the standard reference range and the reference range for children with sickle cell anaemia determined among the study subjects with the upper and lower limits of the reference range determined in the present study being generally lower than the standard reference values

Summary

Introduction

Sickle cell disease is one of the commonest single gene disorders in man.[1]. The burden of the disease is highest in sub-Saharan Africa, especially in Nigeria, where approximately 6 million people are projected to be afflicted.[2]. The authors reported that a combination of low haemoglobin concentration below 11.0g/dLand low MCV below 70fl was a poor screening tool for iron deficiency anaemia in children with sickle cell anaemia. This may be due to the fact that sickle cell anaemia sometimes may be associated with relative microcytosis in the absence of iron deficiency, which is assumed to be the consequence of reduced haemoglobin production.[25] ; this cut off value would include a small number of children with sickle cell anaemia without iron deficiency anaemia. The aim of the present study was to explore red cell indices cut-off values useful as a surrogate for detecting iron deficiency in children with sickle cell anaemia where serum ferritin estimation is not available

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Discussion

Conclusion