Prevalence and Predictors of Vitamin D Deficiency Among Children Attending Makongoro Reproductive and Child Health Clinic in Mwanza, Tanzania

Abstract

Background: Vitamin D deficiency (VDD) is a global public health problem which affects all age groups and it is prevalent even in countries with adequate sunlight due to inadequate sunlight exposure and consumption of diet poor in vitamin D. The effects of VDD peak between 3 to 18 months due to increased requirement of vitamin D. This study was done in order to determine the prevalence and predictors of VDD among children attending Makongoro reproductive and child health (RCH) in Mwanza, Tanzania
Methods: This was a cross sectional study involving children aged 1 month and 2 weeks to 24 months attending Makongoro RCH clinic in Mwanza Tanzania. The sample size for prevalence was estimated using Kish Leslie formula while double proportion formula was used for calculations of predictors of low serum vitamin D levels. Convenient sampling was therefore used to recruit 305 children who met the inclusion criteria. Social demographic and clinical data were obtained using data collection tool. Rapid vitamin D (25-hydroxy-vitamin-D [25(OH)D]) test was done followed by serum 25(OH)D and calcium levels in all children with positive rapid 25(OH)D test results. Vitamin D deficiency was defined as serum levels <20ng/ml and Vitamin D insufficiency (VDI) when levels were between 20 and 30ng/ml. Hypocalcaemia was defined as serum ionized calcium <1.17mmol/l. Data was analyzed using STATA version 13.
Results: A total of 305 children were enrolled in this study. While normal serum vitamin D levels were observed in 80% of the studied children, 9% had VDI and 11% had VDD. Low serum vitamin D levels were independently associated with prematurity (OR 6.9, 95% CI; 2.28-20.69,P=.001), delayed milestones (OR 3.3, 95% CI; 1.38-28.57, P =.03), inadequate sun exposure (OR 12, 95% CI; 4.14-35.49, P<.001) and malnutrition (OR= 7.9, 95% CI; 1.91-32.96, P=.004). Hypocalcaemia was observed in 24% of children with low serum vitamin D levels.
Conclusion: Substantial proportion of children attending Makongoro RCH clinic have VDD. Prematurity, inadequate sun exposure, malnutrition and delayed milestones significantly predicted low serum vitamin D levels hence screening should be prioritized in children with these conditions.