Title

Prevalence of vitamin D deficiency in exclusively breastfed infants at the Aga Khan University Hospital, Nairobi

Date of Award

2015

Document Type

Dissertation

Degree Name

Master of Medicine (MMed)

First Supervisor/Advisor

Dr. Rose Kamenwa

Second Supervisor/Advisor

Dr William M Macharia

Third Supervisor/Advisor

Dr. Mary. S.Limbe

Department

Paediatrics and Child Health (East Africa)

Abstract

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.

This document is available in the relevant AKU library

Share

COinS