Renal Function Considerations in the Evaluation of Markedly Elevated Vitamin B12

Laboratory Assessment

• Include renal function tests (serum creatinine and estimated glomerular filtration rate) as part of the comprehensive metabolic panel when investigating persistent hypercobalaminemia, to identify possible renal impairment that may influence B12 levels. 1

Interpretation of Elevated B12 in the Context of Renal Insufficiency

• Recognize that chronic renal insufficiency can cause falsely high serum vitamin B12 and its metabolites, which may confound the diagnostic work‑up for underlying malignancy or liver disease; therefore, abnormal renal function should be taken into account when interpreting markedly elevated B12 results. 1