Background To assess utility of novel biomarkers in diagnosing children with clinical cobalamin deficiency. Current practice uses total vitamin B12 levels to confirm diagnosis, which lacks sensitivity when used in isolation. Methods Between November 2020 and September 2022, a prospective cross-sectional study was carried out in a tertiary teaching hospital. Children between 1 month-18 years with clinical symptoms/at-risk of developing B12 deficiency were included. Relevant clinical and laboratory information (including total B12 and biomarker levels) were documented. Sensitivity and specificity of individual biomarkers was assessed using 4cB12, an indicator of functional B12 status. Version 4.2.1 of R language was used for statistical analysis. Results Analysis was done on sixty-seven children. Anorexia, fatigue and behavioural abnormalities were among the leading clinical characteristics. 49% children had peripheral smear(PS) suggestive of cobalamin deficiency, 43% had low total B12 levels. Among biomarkers, 85% children had low Holotranscobalamin(HoloTC), 73% and 55% had high Methylmalonic acid(MMA) and elevated Homocysteine(Hcy) levels respectively. Sensitivity of total B12 was 51%, HoloTC 87%, MMA 83% and Hcy 64%. Combination of low HoloTC, macrocytosis and abnormal PS had 94% sensitivity while HoloTC with mean corpuscular volume(MCV) alone was 88% sensitive in detecting cobalamin deficiency. Conclusion Low total B12 levels lack sensitivity to diagnose cobalamin deficiency. Although combination of low HoloTC with abnormal smear and macrocytosis was found to have better sensitivity, reporting an abnormal smear is time consuming, requires skilled personnel. Combination of low HoloTC with macrocytosis has good sensitivity, can be considered a better screening tool for detecting B12 deficiency.
Keywords: Analytes; Clinical studies; Haemoglobin; Nutrition.