Meir H Kryger1, Kazuo Otake, John Foerster. 1. Sleep Disorders Centre, St. Boniface General Hospital, R2034, 351 Tache Avenue, Winnipeg, Manitoba, R2H 2A6, Canada. kryger@sleep.umanitoba.ca
Abstract
BACKGROUND: It has been shown that restless legs syndrome (RLS) in adults may be linked to abnormalities in iron stores. Whether reduced iron stores play a role in children is not clear. METHODS: We evaluated the status of iron stores and sleep in three teenagers who presented with severe sleep onset insomnia, subjective sleep latency exceeding 60 min and excessive daytime sleepiness. RESULTS: The three teenagers were found to have RLS and laboratory evaluation confirmed reduced body stores of iron with a low percent iron saturation (mean value 9.7%) and a low serum ferritin level (mean value 17 microg/l). None had marked anemia. The three patients were treated with oral iron for 4-5 months. As a group they had an increase in percent iron saturation (from a mean of 9.7 to 22.7%) and serum ferritin (from a mean of 17 to 27 microg/l) and a marked reduction of the symptoms of RLS, with mean subjective sleep latency decreasing from 143 to 23 min, sleep efficiency increasing from 75.7 to 84.0% and the number of periodic movements per hour of sleep decreasing from 20.5 to 10.5. INTERPRETATION: These findings support the hypothesis that abnormal iron stores or metabolism may result in RLS causing insomnia in teenagers. We recommend evaluation of iron status including serum iron, total iron binding capacity and ferritin levels in teenagers with chronic insomnia of unexplained origin even when anemia is mild or absent.
BACKGROUND: It has been shown that restless legs syndrome (RLS) in adults may be linked to abnormalities in iron stores. Whether reduced iron stores play a role in children is not clear. METHODS: We evaluated the status of iron stores and sleep in three teenagers who presented with severe sleep onset insomnia, subjective sleep latency exceeding 60 min and excessive daytime sleepiness. RESULTS: The three teenagers were found to have RLS and laboratory evaluation confirmed reduced body stores of iron with a low percent iron saturation (mean value 9.7%) and a low serum ferritin level (mean value 17 microg/l). None had marked anemia. The three patients were treated with oral iron for 4-5 months. As a group they had an increase in percent iron saturation (from a mean of 9.7 to 22.7%) and serum ferritin (from a mean of 17 to 27 microg/l) and a marked reduction of the symptoms of RLS, with mean subjective sleep latency decreasing from 143 to 23 min, sleep efficiency increasing from 75.7 to 84.0% and the number of periodic movements per hour of sleep decreasing from 20.5 to 10.5. INTERPRETATION: These findings support the hypothesis that abnormal iron stores or metabolism may result in RLS causing insomnia in teenagers. We recommend evaluation of iron status including serum iron, total iron binding capacity and ferritin levels in teenagers with chronic insomnia of unexplained origin even when anemia is mild or absent.
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