Iron deficiency and sleep-related breathing disorders in children with epilepsy

Abstract

<h3>Introduction</h3> Iron plays an important role in the developing brain (including myelination, synaptogenesis and neurotransmission) and deficiency has been linked to difficulties in behaviour, cognitive ability and paediatric sleep disturbances. Iron also has a key role in immunity and deficiency is linked to adenotonsillar hypertrophy and obstructive sleep apnoea (OSA, measurable as Δ 12 index on pulse oximetry), which may in turn affect seizure control in epileptic children, although there are few studies investigating the possibility of a link. <h3>Methods</h3> An audit was undertaken of laboratory results of 38 tertiary centre children with epilepsy, 30 of whom had overnight pulse oximetry because of symptoms of sleep-related breathing disorder. Full blood counts were retrieved from the hospital electronic system, and the red cell indices were correlated with the average and minimum haemoglobin oxygen saturation (SpO₂), the total number of desaturations and, where available, the Δ 12 Index. <h3>Results</h3> Twenty-two (58%) of the 38 children had low haemoglobin for age, 28 (74%) had low haematocrit, 6 (16%) had low mean cell haemoglobin (MCH) and 5 (13%) had low mean cell volume. In the 30 children with pulse oximetry (12 boys, median age 7.3 (range 3.0–16.6) years), there were correlations between number of desaturations and MCH (r=−0.391; p=0.04), haematocrit (r=−0.393, p=0.04) and haemoglobin (r=−0.428, p=0.02), but there was no relationship between average or minimum overnight SpO₂ and the red cell indices. In the 16 children for whom Δ 12 index and red cell indices were available, there were correlations with haematocrit (r=−0.556, p=0.03) and haemoglobin (r=−0.571, p=0.02). <h3>Discussion</h3> Epilepsy, iron deficiency and sleep-related breathing disorders are all common paediatric problems. Indices suggesting iron deficiency appear to be common in children with epilepsy and to be associated with the number of desaturations overnight and with an index of OSA. Further research is needed to see if these children are actually iron deficient and if restoring iron stores improves the sleep disturbance. As treatment of OSA has been shown to improve seizure control in adults, the possibility that restoration of iron stores reduces seizure frequency in this subgroup of patients should be explored.