A 68-year-old client with a history of total gastrectomy presents with paresthesias in the bilateral lower extremities, an unsteady gait, and a sore, smooth, beefy red tongue. The laboratory reports an MCV of 114 fL. The nurse identifies that this client requires which definitive lifelong treatment?

Gastrectomy eliminates the gastric parietal cells responsible for secreting Intrinsic Factor, leading to an absolute inability to absorb oral Vitamin B12 and resulting in Pernicious Anemia (a macrocytic megaloblastic anemia). The hallmark distinguishing B12 deficiency from folic acid deficiency is neurological impairment (peripheral neuropathy, paresthesias, ataxia, subacute combined degeneration of the spinal cord). Because enteral absorption is permanently compromised, the client requires lifelong parenteral (intramuscular or deep subcutaneous) Vitamin B12 replacement. Administering folic acid alone may improve hematologic counts but masks and allows irreversible neurological damage to progress.