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Sleep Med. 2015 Nov;16(11):1413-1418. doi: 10.1016/j.sleep.2015.05.015. Epub 2015 Jun 18.

Association of low ferritin with PLM in the Wisconsin Sleep Cohort.

Author information

1
Center for Sleep Sciences and Medicine, Stanford University, Palo Alto, CA, USA.
2
Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, USA.
3
Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, USA. Electronic address: mignot@stanford.edu.

Abstract

OBJECTIVE:

The origins of periodic leg movements (PLMs), a strong correlate of restless legs syndrome (RLS), are uncertain. This study was performed to assess the relationship between PLMs and peripheral iron deficiency, as measured with ferritin levels corrected for inflammation.

METHODS:

We included a cross-sectional sample of a cohort study of 801 randomly selected people (n = 1008 assays, mean age 58.6 ± 0.3 years) from Wisconsin state employee agencies. A previously validated automatic detector was used to measure PLMs during sleep. The patients were categorized into RLS symptoms-positive and RLS symptoms-negative based on a mailed survey response and prior analysis. Analyses were performed using a linear model with PLM category above and below 15 PLM/h (periodic leg movement index, PLMI) as the dependent variable, and adjusting for known covariates, including previously associated single-nucleotide polymorphisms (SNPs) within BTBD9, TOX3/BC034767, MEIS1, MAP2K5/SKOR1, and PTPRD. Ferritin and C-reactive protein (CRP) levels were measured in serum, and ferritin levels corrected for inflammation using CRP levels.

RESULTS:

After controlling for cofactors, PLMI ≥ 15 was associated with low (≤50 ng/mL) ferritin levels (OR = 1.55, p = 0.020). The best model was found using quasi-least squares regression of ferritin as a function of PLMI, with an increase of 0.0034 PLM/h predicted by a decrease of 1 ng/mL ferritin (p = 0.00447).

CONCLUSIONS:

An association was found between low ferritin and greater PLMs in a general population of older adults, independent of genetic polymorphisms, suggesting a role of low iron stores in the expression of these phenotypes. Patients with high PLMI may require to be checked for iron deficiency.

KEYWORDS:

Ferritin; Iron; Periodic leg movements; Restless legs syndrome; Wisconsin Sleep Cohort

PMID:
26498245
DOI:
10.1016/j.sleep.2015.05.015
[Indexed for MEDLINE]

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