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Italian youth vitamin D deficiency increased likelihood: 27X if winter, 5X if obese, etc. – Aug 2013

Vitamin D status and predictors of hypovitaminosis D in Italian children and adolescents: a cross-sectional study.

Eur J Pediatr. 2013 Aug 20.
Vierucci F, Del Pistoia M, Fanos M, Gori M, Carlone G, Erba P, Massimetti G, Federico G, Saggese G.
Pediatric Unit, Department of Pediatrics, Santa Chiara University Hospital, Via Roma 67, 56126, Pisa, Italy, vieruf at hotmail.it.

Hypovitaminosis D affects children and adolescents all around the world. Italian data on vitamin D status and risk factors for hypovitaminosis D during pediatric age are lacking. Six hundred fifty-two children and adolescents (range 2.0-21.0 years) living in the northwestern area of Tuscany were recruited at the Department of Pediatrics, University Hospital Pisa. None of them had received vitamin D supplementation in the previous 12 months. 25-hydroxyvitamin D (25-OH-D) and parathyroid hormone (PTH) levels were analyzed in all subjects. Severe vitamin D deficiency was defined as serum levels of 25-OH-D < 25.0 nmol/L (10.0 ng/mL) and vitamin D deficiency as < 50.0 nmol/L (20.0 ng/mL). Serum 25-OH-D levels of 50.0-74.9 nmol/L (20.0-29.9 ng/mL) indicated vitamin D insufficiency, whereas 25-OH-D levels ≥ 75.0 nmol/L (30.0 ng/mL) were considered sufficient. Hypovitaminosis D was defined as 25-OH-D levels < 75.0 nmol/L (30.0 ng/mL). The median serum 25-OH-D level was 51.8 nmol/L, range 6.7-174.7 (20.7 ng/mL, range 2.7-70.0), with a prevalence of vitamin D deficiency, insufficiency, and sufficiency of 45.9, 33.6, and 20.5 %, respectively. The prevalence of severe vitamin D deficiency was 9.5 %. Adolescents had lower median 25-OH-D levels (49.8 nmol/L, range 8.1-174.7; 20.0 ng/mL, range 3.2-70.0) than children (55.6 nmol/L, range 6.8-154.6; 22.3 ng/mL, range 2.7-61.9, p = 0.006). Non-white individuals (n = 37) had median serum 25-OH-D levels in the range of deficiency (28.2 nmol/L, range 8.1-86.2; 11.3 ng/mL, range 3.2-34.5), with 36/37 having hypovitaminosis D. Logistic regression showed significant increased risk of hypovitaminosis D in the following: blood samples taken in winter (odds ratio (OR) 27.20), spring (OR 26.44), and fall (OR 8.27) compared to summer; overweight (OR 5.02) and obese (OR 5.36) subjects compared to individuals with normal BMI; low sun exposure (OR 8.64) compared to good exposure, and regular use of sunscreens (OR 7.06) compared to non-regular use.
Gender and place of residence were not associated with vitamin D status.
The 25-OH-D levels were inversely related to the PTH levels (r = -0.395, p < 0.0001).
Sixty-three out of the 652 (9.7 %) subjects showed secondary hyperparathyroidism.

Conclusion Italian children and adolescents who were not receiving vitamin D supplementation had high prevalence of hypovitaminosis D.
Careful identification of factors affecting vitamin D status is advisable to promptly start vitamin D supplementation in children and adolescents.

PMID: 23959324

Summary by VitaminDWiki: Odds ratio for < 30 ng/ml of vitamin D

Winter 27X
Spring 26X
Overweight 5X
Low sun exposure9X
Use of sunscreens7X

Seems similar to other studies. Interesting that they did not study skin color, which might have been a 10X to 100X factor

See also VitaminDWiki