Objective:
Observational studies suggest that low vitamin D levels may promote hypertension. Aim was to assess vitamin D status in children and adolescents with arterial hypertension and to find relation between vitamin D and clinical, biochemical and ABPM parameters.
Design and method:
Study group included 49 pediatric patients aged 14.29 ± 3.17 years with arterial hypertension; 24 children received antihypertensive medications. In all patients we evaluated vitamin D status, serum calcium, phosphorus, parathormone, alkaline phosphatase, urinary calcium and phosphorus loss, office blood pressure, ABPM, height, weight and BMI, GFR, uric acid, lipids and albuminuria. Children were not supplemented with vitamin D. According to Central European Guidelines vitamin D status was defined as: deficiency (<20 ng/mL), suboptimal status (20–30 ng/ml), adequate status (>30 to 50 ng/mL), high supply (> 50 to 100 ng/mL).
Results:
Vitamin D level was from 6.1 to 55.3, mean 19.74 ± 9.68 ng/mL. Vitamin D deficiency was found in 29 (59.2%), suboptimal status in 17 (34.7%), adequate status in 1 (2.0%), high supply in 2 (4.1%) children. Vitamin D level was higher in Spring-Summer months compared to Autumn-Winter months (21.79 ± 10.19 vs. 15.53 ± 7.08 ng/mL, p = 0.031), did not differ between boys and girls (20.14 ± 11.13 vs. 18.83 ± 5.25 ng/mL, p = 0.974) and between treated and untreated children (20.72 ± 12.71 vs. 18.80 ± 5.53 ng/mL, p = 0.031). Other parameters of calcium-phosphorus metabolism were within normal limits in all children. Vitamin D level correlated with height Z-score (R = 0.39, p = 0.003), BMI Z-score (r = −0.34, p = 0.016), uric acid (r = −0.31, p = 0.044) and triglycerides (r = −0.37, p = 0.014). Vitamin D level correlated negatively with mean 24-hour heart rate (r = −0.38, p = 0.007); whereas no relation was found between vitamin D and age. In the subgroup of 24 children treated with antihypertensive medications (mean duration of hypertension 23.54 ± 21.64 months) vitamin D correlated with ambulatory arterial stiffness index (r = 0.50, p = 0.036).
Conclusions:
- Inadequate supply (deficiency or suboptimal status) is ubiquitous in children with arterial hypertension.
- Vitamin D deficiency should be suspected especially in Autumn-Winter period and among obese and short children.
- The relation between vitamin D status and ambulatory arterial stiffness index suggests negative influence of vitamin D on arterial wall but requires further examinations.
