(P01-005-23) Comparison of Serum Retinol and the Modified Relative Dose Response Test for Vitamin A Deficiency in Women of Reproductive Age in Nigeria

Objectives: Our objective was to assess the accuracy of serum retinol to determine vitamin A deficiency compared with the modified relative dose response test (MRDR) in women of reproductive age from the Nigerian National Food Consumption and Micronutrient Survey.

Methods: This survey used a cross-sectional, two-stage sampling design. Estimates were calculated using the sampling design weight; confidence intervals were symmetric and calculated using standard error. A 20% subsample of non-pregnant women 15-49 years old were selected for MRDR determination. For the MRDR assay, an 8.8 µmol dose of vitamin A2 was orally administered, and venous blood was collected 4-6 hours later. Serum retinol and vitamin A2 were quantified using high-performance liquid chromatography, and MRDR values were calculated as the molar ratio of serum vitamin A2:retinol. Cutoffs for deficiency were MRDR values ≥ 0.060 and retinol < 0.70 µmol/L.

Results: A total of 1,140 women had complete data and were included in this analysis. Mean (95% CI) age was 30.2 (29.6, 30.9) years, BMI was 23.9 (23.5, 24.3) kg/m2, retinol was 1.09 (1.05, 1.14) µmol/L, and MRDR was 0.01 (0.01, 0.01). Serum retinol and MRDR were not correlated. Serum retinol was < 0.70 µmol/L in 28.9 (25.8, 32.2)%, while none had MRDR ≥ 0.060. For serum retinol to determine vitamin A deficiency compared to the MRDR, sensitivity was undefined due to no positive MRDR values, and specificity was 71.1 (67.8, 74.2)%.

Conclusions: The discordance in estimates of vitamin A deficiency merits further investigation to more accurately determine vitamin A status and guide interventions. Future directions include examining inflammation and malaria as covariates, determining complementary vitamin A biomarkers, and combining these results with dietary intakes.

Funding Sources: The Nigerian National Food Consumption and Micronutrient Survey received funding from the Bill and Melinda Gates Foundation, World Bank, US Aid for International Development, Nutrition International, UNICEF, and International Institute of Tropical Agriculture.