Gastrectomy causes vitamin B-12 deficiency since vitamin B-12 requires gastric acid and intrinsic factor for its absorption. Vitamin B-12 deficiency is considered to develop years after gastrectomy because of large hepatic storage. However, most gastric cancer develops after long-standing atrophic gastritis with vitamin B-12 malabsorption.
We have investigated vita-min B-12 status in 22 patients before gastrectomy and 53 patients after gastrectomy due to gastric cancer, also with consideration on post-gastrectomy anemia.
Blood vitamin B-12, folic acid, homocysteine concentrations, parameters of anemia, and dietary intake were evaluated. Percentage of patients with severe vitamin B-12 deficiency (serum vitamin B-12 < 150 pmol/L), vitamin B-12 deficiency (150 pmol/L to < 258 pmol/L) was 19.0 %, and 52.4 % respectively in patients gastrectomized within three years. Before gastrectomy, three and seven patients exhibited severe deficiency and deficiency, respectively. In gastrectomized patients, plasma homocysteine concentration was inversely associated with serum vitamin B-12 concentration, and vitamin B-12 deficiency- and iron deficiency- anemia coexisted with their mean corpuscular volume within the reference range.
Vitamin B-12 deficiency is prevalent in patients early after and before gastrectomy. Coexistence of vitamin B-12 and iron deficiency obscures the diagnosis of post-gastrectomy anemia, and necessitates the blood vitamin B-12 measurement.