Deficiency of cobalamin (vitamin B12) is determined in laboratory with various strategies that measure different biomarkers such as vitamin B12, holotranscobolamin or both simultaneously. However, patient history and clinical signs should also be considered when posing the diagnosis. We aim at exploring which laboratory strategy is cost-efficient in the clinical setting. We will analyse retrospectively laboratory data.

We also aim at investigating the awareness of cobalamin deficiency in the population at risk (such as older adults, vegetarians, vegans). We will determine patient preferences for substitution treatment that guarantees best medication adherence. We wil conduct focus group discussions.