IRON STORES, PERIODIC LEG MOVEMENTS, AND SLEEPINESS IN OBSTRUCTIVE SLEEP APNEA

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Periodic leg movements during sleep (PLMS) are brief, repeated leg jerks that may be associated with arousals from sleep and excessive daytime sleepiness. PLMS and restless legs syndrome, which is a disorder characterized by bothersome leg sensations and restlessness that happen during wake, are associated with low levels of iron. Previous studies have shown a relationship between PLMS, restless legs syndrome, and low body iron stores (iron was measured indirectly by the amount of ferritin in the blood). Ferritin is a protein that stores iron in the body and the ferritin level in blood is proportional to the amount of iron stored in the body. It is thought that if there is not enough iron in the brain, restless legs syndrome and PLMS may occur. This is because iron is required for the synthesis of dopamine, an important chemical messenger for brain cells. Problems with dopamine transmission is believed to be a cause of restless legs syndrome and PLMS and both conditions improve with dopamine therapy. Dopamine is also believed to have a critical function in sleepiness and alertness. PLMS is common in many other sleep-disrupting conditions, such as obstructive sleep apnea (OSA), a condition characterized by repeated events of full or partial airway obstruction with associated arousals and oxygen desaturation. Excessive sleepiness is a common complaint in patients with OSA. The high frequency of PLMS in disorders of excessive sleepiness raises the possibility that low levels of iron may play a role in OSA. The main aim of this study, therefore, is to determine the relationship between ferritin levels (obtained from a blood sample), PLMS, and daytime sleepiness in patients with OSA. The specific aims are 1) to determine ferritin levels in 80 patients that have suspected OSA; 2) to determine the association between ferritin levels and PLMS; and 3) to determine the association between ferritin levels and daytime sleepiness in patients with OSA. This The results of this study could provide important imformation that will help to understand the role of iron deficiency in other sleep disorders besides RLS and PLMS.'