title: Vitamin D levels and obstructive sleep apnoea in children.
abstract: OBJECTIVE
  Obstructive sleep apnoea (OSA) is a common health problem in children. African American (AA) and obese children have higher prevalence of OSA, and are also at a higher risk of reduced vitamin D levels. We hypothesised that OSA would be associated with lower levels of plasma 25-hydroxyvitamin D (25(OH)D) and increase in the risk of metabolic dysfunction and systemic inflammation.
  
  
  METHODS
  In this observational cross-sectional study, 176 prospectively recruited children (mean age: 6.8±0.8 years) underwent overnight polysomnographic evaluation and a fasting blood draw the morning after the sleep study. In addition to lipid profile, homeostatic model of insulin resistance (HOMA-IR) and high-sensitivity C-reactive protein (hsCRP) assays and plasma 25(OH)D levels were assessed using ELISA kits.
  
  
  RESULTS
  AA children, obese children and children with OSA had significantly lower 25(OH)D levels. Linear associations emerged between 25(OH)D plasma levels and body mass index (BMI) z-score, hsCRP and HOMA-IR, as well as with apnoea-hypopnoea index (AHI) and oxygen saturation (SpO2) nadir, the latter two associations remaining statistically significant even when controlling for all other potential confounders, and independently accounting for 17.7% of the variance in 25(OH)D (p<0.01).
  
  
  CONCLUSIONS
  25(OH)D levels are reduced in paediatric OSA, in AA children and in obese children, particularly when all are present, and may play a role in modulating the degree of insulin resistance and systemic inflammation. The short-term and long-term significance of reduced 25(OH)D in paediatric OSA remains undefined.
authors.affiliation: Section of Sleep Medicine, Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA. Electronic address: lgozal@peds.bsd.uchicago.edu.
authors.forename: Leila
authors.initials: L
authors.lastname: Kheirandish-Gozal
authors.affiliation: Section of Sleep Medicine, Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA.
authors.forename: Eduard
authors.initials: E
authors.lastname: Peris
authors.affiliation: Section of Sleep Medicine, Department of Pediatrics, Pritzker School of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA. Electronic address: dgozal@uchicago.edu.
authors.forename: David
authors.initials: D
authors.lastname: Gozal
mesh_terms: D001741:Black or African American / Q000706:statistics & numerical data; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D002641:Chicago; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008055:Lipids / Q000097:blood; D008297:Male; D009765:Obesity / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology / Q000208:ethnology; D017286:Polysomnography; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology* / Q000208:ethnology; D013223:Statistics as Topic; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology* / Q000208:ethnology; D044465:White People / Q000706:statistics & numerical data
chemical_list: D008055:Lipids; D014807:Vitamin D; D002097:C-Reactive Protein; C104450:25-hydroxyvitamin D
keywords: Children; Insulin resistance; Metabolism; Sleep apnoea; Systemic inflammation; Vitamin D