title: Prevalence of hypovitaminosis D and predictors of vitamin D status in Italian healthy adolescents.
abstract: BACKGROUND
  Vitamin D plays an important role in health promotion during adolescence. Vitamin D deficiency and insufficiency are common in adolescents worldwide. Few data on vitamin D status and risk factors for hypovitaminosis D in Italian adolescents are currently available.
  
  
  METHODS
  25-hydroxyvitamin D (25-OH-D) and parathyroid hormone (PTH) levels were evaluated in 427 Italian healthy adolescents (10.0-21.0 years). We used the following cut-off of 25-OH-D to define vitamin D status: deficiency < 50 nmol/L; insufficiency 50-75 nmol/L; sufficiency ≥ 75 nmol/L. Hypovitaminosis D was defined as 25-OH-D levels < 75.0 nmol/L and severe vitamin D deficiency as 25-OH-D levels < 25.0 nmol/L. We evaluated gender, residence, season of blood withdrawal, ethnicity, weight status, sun exposure, use of sunscreens, outdoor physical activity, and history of fractures as predictors of vitamin D status.
  
  
  RESULTS
  Enrolled adolescents had a median serum 25-OH-D level of 50.0 nmol/L, range 8.1-174.7, with 82.2% having hypovitaminosis D. Vitamin D deficiency and insufficiency were detected in 49.9% and 32.3% of adolescents, respectively. Among those with deficiency, 38 subjects were severely deficient (38/427, 8.9% of the entire sample). Non-white adolescents had a higher prevalence of severe vitamin D deficiency than white subjects (6/17-35.3% vs 32/410-7.8% respectively, p = 0.002). Logistic regression showed increased risk of hypovitaminosis D as follows: blood withdrawal taken in winter-spring (Odds ratio (OR) 5.64) compared to summer-fall period; overweight-obese adolescents (OR 3.89) compared to subjects with normal body mass index (BMI); low sun exposure (OR 5.94) compared to moderate-good exposure and regular use of sunscreens (OR 5.89) compared to non regular use. Adolescents who performed < 3 hours/week of outdoor exercise had higher prevalence of hypovitaminosis D. Gender, residence, and history of fractures were not associated with vitamin D status. Serum 25-OH-D levels were inversely related to PTH (r = -0.387, p < 0.0001) and BMI-SDS (r = -0.141, p = 0.007). 44/427 (10.3%) adolescents showed secondary hyperparathyroidism.
  
  
  CONCLUSIONS
  Italian adolescents have high prevalence of vitamin D deficiency and insufficiency. Pediatricians should tackle predictors of vitamin D status, favoring a healthier lifestyle and promoting supplementation in the groups at higher risk of hypovitaminosis D.
authors.affiliation: Pediatric Unit, Campo di Marte Hospital, Via Ospedale 1, 55100 Lucca, Italy. vieruf@hotmail.it.
authors.forename: Francesco
authors.initials: F
authors.lastname: Vierucci
authors.forename: Marta
authors.initials: M
authors.lastname: Del Pistoia
authors.forename: Margherita
authors.initials: M
authors.lastname: Fanos
authors.forename: Paola
authors.initials: P
authors.lastname: Erba
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Saggese
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D016017:Odds Ratio; D010281:Parathyroid Hormone / Q000097:blood*; D015995:Prevalence; D012016:Reference Values; D012189:Retrospective Studies; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D