Prevalence of hypovitaminosis D and predictors of vitamin D status in Italian healthy adolescents

Abstract

BackgroundVitamin 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.Methods25-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.ResultsEnrolled 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.ConclusionsItalian 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.

Is There Any Threshold for Vitamin D That Elevates Parathyroid Hormone

“…In contrast to data from past studies indicated that season of blood withdrawal was a significant predictor of vitamin D status, with identification of lower median 25(OH) D levels during winter and spring [36] [37] [38], seasonal alteration had no influence on 25(OH) D levels as well as corrected calcium levels in our study population, whereas serum PTH levels were higher in summer cases, especially among females. Lack of the effect of seasonal difference on serum vitamin D levels was also reported in a past study in stroke patients which revealed similar levels for vitamin D levels between the cases in summer (Apr-Sep) and winter (Oct-Mar) [39].…”

“…In this regard, our findings may emphasize the insufficient exposure to sunlight even in summer months during which sun exposure is more effective in promoting vitamin D activation as well as its storage for an optimal vitamin D status during the remaining months of the year [36].…”

Hypovitaminosis D and Low Bone Mineral Density in Inflammatory Bowel Disease Patients

“…In particular, a recent study conducted on over 400 healthy adolescents in Tuscany (10-21 years old) showed a prevalence of hypovitaminosis D equal to 82.2%, with 32.3% of insufficiency and 49.9% of deficiency [17]. These results suggest that the high percentage of hypovitaminosis D observed in our series might be primitive and probably gained before the onset of the disease.…”

Vitamin D deficiency among high school female students in Riyadh

“…Among those with deficiency, Nonwhite adolescents had a higher prevalence of severe vitamin D deficiency than white adolescents. Adolescents who performed <3 hours/week of outdoor exercise had higher prevalence of hypovitaminosis D [10].…”