Abstract Introduction Iron deficiency (ID) is common among children and adults with cystic fibrosis (CF) and appears to persist even after the use of highly effective modulator therapy (HEMT). There is an association between ID and restless sleep and frequent limb movements during sleep in children. However, little data exists on whether these same associations are present in children with CF. Methods Single-center retrospective review of medical records and polysomnographic data in children with CF between 2012-2025 to identify the prevalence of ID and its association with sleep complaints and disordered sleep. Results Polysomnographic data was available for 54 children with CF. Thirty-six were on HEMT for an average of 2.2±1.6 years prior to polysomnography. Children on HEMT were older (10.1 vs 6.1 years, respectively; p=0.001) and had better lung function (98.4 vs 88.2%, respectively; p=0.02) as compared to those not on HEMT. Nutritional status was normal, on average, and similar between the groups (p=0.3). Iron deficiency (ferritin 30 ng/mL) was present in 73% of children with 20% also having anemia (low hemoglobin level). Low iron stores (ferritin 50 ng/mL) were noted in 92% of children. Prevalence of ID did not differ by sex, nutritional status, lung function, or HEMT status. Sleep complaints were common (snoring: 72%, restless sleep: 68%, insomnia: 49%, hypersomnolence 34%); 57% had obstructive sleep apnea (OSA) and 9% had frequent limb movements during sleep (PLMS). Children on HEMT had 4.0 times greater odds of OSA (95%CI:1.3-12.2; p=0.02) and 3.0 times greater odds of Insomnia (95%CI:0.9-9.8; p=0.06) as compared to those not on HEMT. Four of the five children with PLMS were on HEMT. ID was associated with restless sleep (OR=5.5; 95%CI: 1.1-28.2; p=0.04). ID was also present in 10/11 children (91%) with hypersomnolence (p=0.1) and 16/19 children (84%) with insomnia (p=0.09). All 3 children with PLMS who had iron studies were noted to have ID. Conclusion ID is common among children with CF, even in the post-HEMT era and appears to be associated with poor sleep. Prospective screening for ID is needed in all children with CF. Larger studies are needed to understand the etiology behind this deficiency. Support (if any)
Aarti Shakkottai (Fri,) studied this question.