Prevalence of vitamin D deficiency in exclusively breastfed infants at the Aga Khan University Hospital, Nairobi
Date of Award
Master of Medicine (MMed)
Dr. Rose Kamenwa
Dr William M Macharia
Dr. Mary. S.Limbe
Paediatrics and Child Health (East Africa)
Introduction: Vitamin D deficiency in infants is a recognized cause of rickets. In the last few years, evidence has emerged of its association with lower respiratory tract infections, food allergy, type 1 diabetes, schizophrenia and various other extra skeletal health effects. Exclusively breastfed infants are especially vulnerable to vitamin D deficiency due to their dependence on previous trans-placental transfer of vitamin D from the mother, dietary vitamin D from breast milk and cutaneous synthesis of vitamin D on exposure to sunlight. The worldwide epidemic of Vitamin D deficiency in pregnancy and the low content of vitamin D in breast milk underlie the high risk of deficiency in exclusively breastfed infants.
Data regarding the magnitude of vitamin D deficiency among exclusively breastfed infants in Kenya is needed to inform policies on supplementation of at risk groups.
Objectives: The aim of this study was to determine the prevalence of vitamin D deficiency in exclusively breastfed infants using 25(OH)D and to evaluate the relationship between PTH and 25(OH)D in a population of exclusively breast fed infants.
Study Design: This was a cross sectional survey carried out in three to six month old exclusively breastfed infants at the Aga Khan University Hospital, Nairobi.
Methods: Ninety-eight infants were enrolled in the study and all had data on their demographics and anthropometric measures recorded. Self-reported data on maternal vitamin D supplementation and sunlight exposure was also collected. A brief physical examination to assess for skeletal signs of rickets was then performed. A blood sample was collected for measurement of serum 25(OH)D, calcium, phosphate and PTH . Prevalence of vitamin D deficiency was analyzed using proportions with 25(OH)D levels below 20ng/ml. PTH, calcium and phosphate levels in the vitamin D deficient and non-deficient groups were compared using analysis of variance(ANOVA). The level of 25(OH)D beyond which there was no PTH elevation was identified by drawing a scatter plot of PTH against vitamin D levels. Tests of association using odds ratio were used to determine the correlation between infant serum vitamin D levels and maternal vitamin D supplementation and sunlight exposure. Skeletal manifestations of vitamin D deficiency in this population were described using bar charts.
Results: Prevalence of vitamin D deficiency among exclusively breastfed infants at Aga Khan University Hospital was 23.5% (95% CI 14.9%-32.0%). A further 31.6% were found to have insufficient levels of vitamin D leaving only 44.9% of the population classified as having sufficient levels. At a vitamin D level of 30ng/ml, only one study participant had an elevated PTH while at vitamin D level of 40ng/ml no study participant demonstrated elevated PTH levels. Using 30ng/ml as the established vitamin D “normal” cut-off for this population, the prevalence of vitamin D deficiency was 55.1%. There was no significant association between infant vitamin D levels and infant sun exposure or maternal sun exposure. Only four mothers had received vitamin D supplements during breastfeeding and their infants were all vitamin D replete. Less than 5% of the study population manifested skeletal signs of rickets.
Conclusion: This study found an unacceptably high level of Vitamin D deficiency among breast fed infants at AKUHN. Whereas more research is needed to identify interventions that would be most effective in reducing Vitamin D deficiency in this population at a time when exclusive breast feeding is emphasized as best practice, findings also support recommendation of many international professional associations for universal supplementation.
Said, N. A. (2015). Prevalence of vitamin D deficiency in exclusively breastfed infants at the Aga Khan University Hospital, Nairobi (Unpublished master's dissertation). Aga Khan University, East Africa.