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Periodic limb movements in sleep and iron status in children
Narong Simakajornboon1, David Gozal, Vukmir Vlasic
1Department of Pediatrics, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA. nsimaka@tulane.edu
Insights
Low serum iron and ferritin levels are common in children with periodic limb movement in sleep (PLMS). Iron therapy significantly improved PLMS severity in most pediatric patients, highlighting its therapeutic potential.
Area of Science:
- Pediatric Sleep Medicine
- Iron Metabolism
- Neurology
Background:
- Periodic Limb Movement in Sleep (PLMS) is a sleep disorder affecting children.
- Iron deficiency is a potential contributing factor to PLMS, but its relationship with severity and treatment response requires further investigation.
Purpose of the Study:
- To investigate the association between serum iron and ferritin levels and PLMS severity in children.
- To evaluate the efficacy of iron supplementation in treating PLMS in pediatric patients.
Main Methods:
- Prospective study of children diagnosed with PLMS.
- Assessment of serum iron and ferritin levels, polysomnography (PLMI), and response to iron sulfate therapy.
- Patients with low ferritin (<50 microg/L) received iron supplementation for 3 months.
Main Results:
- A significant correlation was found between lower serum iron levels and higher PLMS severity (PLMI).
- While low ferritin levels were common, the correlation with PLMS severity was not statistically significant.
- Iron therapy led to a significant decrease in PLMI and an increase in ferritin levels in 76% of treated patients.
Conclusions:
- Pediatric PLMS is frequently linked to low serum iron and a tendency towards low ferritin levels.
- Iron supplementation demonstrates clinical improvement in the majority of pediatric patients with PLMS.
Study Objectives:
To assess potential relationships between serum iron and ferritin levels and the severity of periodic limb movement in sleep (PLMS) in a pediatric population, and to evaluate the response to supplemental iron therapy.
Design:
A prospective study of all consecutively diagnosed children with PLMS (periodic limb movement index [periodic limb movements per hour of total sleep time, [PLMI] > 5) who underwent overnight polysomnographic evaluation. In all patients, complete blood count and serum iron and ferritin levels were obtained. Patients with serum ferritin concentrations less than 50 microg/L were prescribed iron sulfate at 3 mg/kg of elemental iron per day for 3 months. At the end of treatment, serum iron and ferritin levels and sleep studies were repeated.
Setting:
Comprehensive Sleep Medicine Center, Tulane University Health Sciences Center, and Kosair Children's Hospital Sleep Medicine and Apnea Center.
Patients:
Twenty boys and 19 girls with PLMS with a mean age of 7.5 +/- 3.1 years.
Intervention:
Iron therapy.
Results:
Twenty-eight (71.8%) patients had ferritin levels less than 50 microg/L. There was no significant correlation between serum ferritin concentration and PLMS severity as indicated by the PLMI (r = -0.19). The PLMI in patients with serum ferritin levels less than 50 microg/L (29.9 +/- 15.5 PLM/h) was higher than in patients with serum ferritin levels greater than 50 microg/L (21.9 +/- 11.8 PLM/h); however, the difference did not achieve statistical significance (P = 0.09). In contrast, serum iron was significantly correlated with PLMI (r = -0.43, P < 0.01). Indeed, patients with serum iron concentrations less than 50 microg/dL had a higher PLMI compared to patients with serum iron concentrations greater than 50 microg/dL (42.8 +/- 18.3 PLM/h and 23.1 +/- 10.1 PLM/h, respectively; P = 0.02). Twenty-five out of the 28 PLMS patients with serum ferritin levels less than 50 microg/L received treatment with iron sulfate, and 19 (76%) responded favorably. Among the responders to iron therapy, PLMI decreased from 27.6 +/- 14.9 PLM per hour to 12.6 +/- 5.3 PLM per hour after 3 months of iron supplements (P < 0.001) and coincided with increases in serum ferritin levels (pre: 40.8 +/- 27.4 microg/L vs post: 74.1 +/- 13.0 microg/L; P < 0.001).
Conclusions:
In children, the presence of PLMS is frequently associated with low serum iron and a tendency toward low serum ferritin levels. In addition, iron therapy is associated with clinical improvement in most of these patients.
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