Iron Stores, Periodic Leg Movements, and Sleepiness in Obstructive Sleep Apnea
| Autor: | Barbara T. Felt, Wattanachai Chotinaiwattarakul, Jocelynn T. Owusu, Ronald D. Chervin, Ludi Fan, Julie Koo, Louise M. O'Brien |
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| Rok vydání: | 2009 |
| Předmět: |
Male
Pulmonary and Respiratory Medicine medicine.medical_specialty Iron Movement Polysomnography Rapid eye movement sleep Excessive daytime sleepiness Comorbidity Disorders of Excessive Somnolence Severity of Illness Index Predictive Value of Tests Surveys and Questionnaires Internal medicine medicine Humans Prospective Studies Restless legs syndrome Leg Sleep Apnea Obstructive medicine.diagnostic_test business.industry Sleep apnea Iron Deficiencies New Research Middle Aged medicine.disease United States Nocturnal Myoclonus Syndrome Causality Obstructive sleep apnea Sleep deprivation Endocrinology Neurology Ferritins Cardiology Female Neurology (clinical) medicine.symptom Deficiency Diseases business Narcolepsy |
| Zdroj: | Journal of Clinical Sleep Medicine. :525-531 |
| ISSN: | 1550-9397 1550-9389 |
| DOI: | 10.5664/jcsm.27652 |
| Popis: | Obstructive sleep apnea (OSA) causes excessive daytime sleepiness in at least 3% of adults, affects many others without causing overt sleepiness, and accounts for the majority of patients seen at sleep disorders centers. Between one quarter and one half of patients evaluated by polysomnography for suspected OSA also prove to have periodic leg movements (PLMs) during sleep.1,2 The PLMs are prominent in most patients with restless legs syndrome (RLS)3 but are also common in other conditions besides OSA that share disturbances of both sleep and dopaminergic transmission. Such conditions include narcolepsy,4 rapid eye movement sleep (REM) behavior disorder,5 Parkinson disease,6 and attention-deficit/hyperactivity disorder.7 The pathophysiology of RLS, and perhaps PLMs as well, may involve iron,8 a rate-limiting cofactor in the synthesis of dopamine, strongly suspected to play key roles in RLS,9 PLMs,10 and normal maintenance of alertness.11 Severity of RLS symptoms is associated with low body iron stores, as reflected by serum ferritin levels.12,13 Whether PLMs are similarly associated with low ferritin levels is less clear. In a study of 39 children with PLMs, no significant association could be demonstrated between ferritin levels and the number of PLMs per hour of sleep (periodic leg movement index, or PLMI).14 A study of 27 adults with RLS similarly found no significant association between ferritin levels and PLMI, though the PLM-arousal index did show a significant relationship.13 In contrast, Earley et al. demonstrated that intravenous administration of iron dextran to patients with RLS substantially decreased PLMs in 5 of 6 subjects whose restless legs also showed prominent improvement.15 In another study, 10 dialysis patients who received oral iron, intravenous iron in some cases, and erythropoietin also showed reduced PLMs.16 Despite these observations, no one knows why PLMs are so common in patients with OSA, or what the clinical significance is (if any) of PLMs found to be comorbid with OSA. Also poorly understood is the common question of why some patients with OSA are severely sleepy, whereas others seem immune to this effect. One possibility not previously examined is that iron deficiency could play a role in sleep disorders other than RLS, and in OSA in particular. Sleep deprivation or other physiologic consequences of OSA could conceivably influence iron absorption, loss, or stores through effects on nutrition consumption,17 gastrointestinal function,18 key metabolic pathways,19 or endocrine function.19 We therefore explored, in an initial manner, several innovative hypotheses, summarized in Figure 1: that OSA could promote iron deficiency, that iron deficiency through a putative effect on dopaminergic transmission could explain PLMS in OSA, and that deficient iron again through effects on dopaminergic systems could help to explain the complaint of sleepiness in many patients with OSA. Figure 1 Novel hypotheses tested in this study were that obstructive sleep apnea promotes deficient body iron stores (Hypothesis 1, H1) and that deficient iron (via an unmeasured influence on dopamine synthesis) promotes both periodic limb movements during sleep ... |
| Databáze: | OpenAIRE |
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