title: Vitamin D deficiency and biochemical variations among urban Saudi adolescent girls according to season.
abstract: OBJECTIVE
  To determine seasonal variations in the vitamin D status of Saudi adolescent girls in Riyadh, Kingdom of Saudi Arabia (KSA) and its effect in biochemical and clinical characteristics.
  
  
  METHODS
  In this prospective study, a total of 2000 Saudi females aged 12-18 years from different schools in Riyadh, KSA participated and submitted a generalized questionnaire with clinical information. Fasting blood samples were obtained in 1618 subjects for the winter season (December to February) and only 499 subjects returned to submit fasting blood samples for the summer season (June-August). Circulating serum 25(OH)D, parathyroid hormone (PTH), and other biomarkers of bone remodeling were measured during both seasons.
  
  
  RESULTS
  Vitamin D deficiency (serum 25(OH)D  less than 25 nmol/L) was significantly higher during summer than winter (63.5% versus 40.8%; p less than 0.001). Mean serum PTH was also significantly higher during summer than winter (p less than 0.01). In all subjects, serum PTH showed a significant inverse association with 25(OH)D at levels below 40 nmol/L (r=-0.21; p less than 0.001). The prevalence of subjects having clinical and metabolic manifestations suggestive of osteomalacia was 2.13% (N=33 out of 1548).
  
  
  CONCLUSIONS
  Seasonal variations in the vitamin D status of Saudi adolescent females significantly modifies biochemical parameters as response to vitamin D status change. In the meantime, heightened public health awareness should be given to populations at higher risk for vitamin D deficiency.
authors: Department of Medicine, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia. E-mail. sulimanirs@gmail.com.
authors: Riad A
authors: RA
authors: Sulimani
authors: Ashry G
authors: AG
authors: Mohammed
authors: Assim A
authors: AA
authors: Alfadda
authors: Suliman N
authors: SN
authors: Alshehri
authors: Abdulaziz M
authors: AM
authors: Al-Othman
authors: Nasser M
authors: NM
authors: Al-Daghri
authors: David A
authors: DA
authors: Hanley
authors: Aliya A
authors: AA
authors: Khan
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D010281:Parathyroid Hormone / Q000097:blood; D011446:Prospective Studies; D012529:Saudi Arabia; D012621:Seasons; D014505:Urban Population; D014807:Vitamin D / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D