**2.2 Clinical examination**

Body measurements (weight and height) were taken in specific conditions (underwear, barefoot). An Año-Sayol scale (reading interval 0–120 kg and a precision of 100 g) was used for weight registration and a Holtain wall stadiometer (reading interval 60–210 cm, precision 0.1 cm) for height registration. The program Aplicación Nutricional, from the Spanish Society of Pediatric Gastroenterology, Hepatology and Nutrition (Sociedad Española de Gastroenterología, Hepatología y Nutrición Pediátrica, available at http://www.gastroinf.es/nutritional/), provided the estimates of the Z-score values of BMI. The reference charts used for comparison were the graphics from Ferrández et al. (Centro Andrea Prader, Zaragoza 2002).

The values of Z-score enabled the assignment of individuals in the following groups:

**17**

*Vitamin D Deficiency in Children*

**2.3 Blood testing**

hyperparathyroidism.

**2.4 Statistical analysis**

**3. Results**

tion status).

*DOI: http://dx.doi.org/10.5772/intechopen.89208*

The plasma levels of calcium and phosphorous were determined in a fasting sample of blood using colorimetric methods in a cobas 8000 analyzer (Roche Diagnostic, Mannheim, Germany). The determination of calcidiol levels required a high-specific chemiluminescence immunoassay (LIAISON Assay, Diasorin, Dietzenbach, Germany) and the determination of PTH levels a highly specific solid-phase, two-site chemiluminescent enzyme-labeled immunometric assay in an

The distribution of individuals according to Vitamin D plasma levels followed the criteria of the US Endocrine Society [21, 22]. Calcidiol plasma levels lower than 20 ng/ml (<50 nmol/L) corresponded to Vitamin D deficiency, calcidiol levels between 20 and 29 ng/ml (50–75 nmol/L) to Vitamin D insufficiency, and concentrations equal to or higher than 30 ng/ml (>75 nmol/L) to Vitamin D sufficiency. PTH serum levels higher than 65 pg/ml [14, 17] determined secondary

The figures resulting from the data collection are shown as percentages (%) and means (M) including the respective standard deviations (SD) or confidence intervals (95% CI). The subsequent statistical analysis (descriptive statistics, Student's t-test, analysis of variance, χ2 test, Pearson's correlation, and multiple logistic regression analysis) was performed using the software package *Statistical Packages for the Social Sciences* version 20.0 (Chicago, IL, USA). A probability value (p-value)

Adequate information of the proceedings and potential implications was delivered to the parents and/or legal guardians, and the corresponding consent was required prior to the inclusion in this study in all cases. The study was presented and approved after the evaluation of the Ethics Committee for Human Investigation at our institution (in line with the ethical standards stated in the Declaration of

The average values for calcidiol and PTH plasma levels from the totality of the collections were 27.4 ± 7.7 ng/mL and 33.2 ± 17.3 pg/mL, respectively. Calcidiol levels overtook 30 ng/mL (Vitamin D sufficiency) in 236 individuals (39.6%), oscillated between 20 and 29 ng/mL (Vitamin D insufficiency) in 266 (44.6%), and were lower than 20 ng/mL (Vitamin D deficiency) in 94 (15.8%). The average values for calcium and phosphorus were 9.9 ± 0.5 and 4.6 ± 0.5 mg/dL, respectively. No values for hypo-/hypercalcemia or hypo-/hyperphosphatemia were detected. The frequency of hyperparathyroidism was significantly higher in the deficient vitamin D (11.6%) and insufficient vitamin D (6.6%) groups, whereas the prevalence of hyperparathyroid-

**Table 1** shows the distribution of the presumed risk factors for hypovitaminosis D (sex, age group, place of residence, season of blood sample collection, and nutri-

**Table 2** shows and compares the mean values for the clinical characteristics and biochemical determinations according to the risk factors for hypovitaminosis D. Mean PTH values were significantly higher (p < 0.05) in females. The average phosphorous values were significantly higher in males (p < 0.05). No significant differences were

ism was lowest in the sufficient vitamin D (2.3%) group (p = 0.005).

Immulite analyzer (DPC Biermann, Bad Nauheim, Germany).

<0.05 was established as the level of statistical significance.

Helsinki, 1964, and later amendments).

