Subacute Combined Degeneration Caused by Chronic Atrophic Gastritis with Spurious Elevation of Vitamin B12 Level

We report a patient who was diagnosed as subacute combined degeneration (SCD) with elevated homocysteine and methylmalonic acid levels in the situation of a spurious elevation of the vitamin B12 concentration. A false-positive elevation of the vitamin B12 level could lead to a delayed diagnosis and cause irreversible changes in the nervous systems. We therefore suggest that the homocysteine and methylmalonic acid levels should be checked in patients with a normal or elevated vitamin B12 level for whom there is a high clinical suspicion for vitamin B12 deficiency, as a further evaluation for SCD.