[Study of cobalamin deficiency in gastrectomized and aged subjects]

The objective of this study were: a) to investigate vitamin B12 deficiency among and advanced aged, clinically healthy, asymptomatic population, presumably with a high prevalence of vitamin B12 deficiency. This deficiency was defined as an increase in the MMA/creatinine ratio in urine and/or basal plasma HT levels which normalize after the administration of vitamin B12; b) its relationship with plasma vitamin B12 levels.

A total of 45 subjects were studied, 19 in the Group of Gastrectomized patients, who were selected on the basis of an age over 60 years and partial gastrectomy of more than five years, and 26 in the Geriatric Group selected in two nursing homes. All of them were asymptopatic and "healthy" according to data in the clinical records and clinical examination, analytical studies, and none of them was taking any drug that might alter results. After basal analytical studies, which included B12, folates, metilmalonic acid/creatinine (MMA/creatinine) in urine and total plasma homocysteine (TH), i.m. vitamin B12 was administered for 15 days to the gastrectomized patients and oral B12 for 28 days with 2.5 mg folic acid for the last 14 days to the patients in the Geriatric Group. Basal analytical studies were repeated at the end of the study.

Basal analytical studies were normal with the exception of two subjects with low levels of hemoglobin and 8 with decreased MCV. Only one subject had decreased serum cobalamines. Nine subjects (20%) were identified with increased basal levels of MMA/creatinine which normalized after decreasing between 97% and 12% after the administration of vitamin B12. TH and MCV also decreased significantly. Basal levels of vitamin B12 ranged from 244 pg/ml to 483 pg/ml (n = 220 pg/ml-980 pg/ml).

Vitamin B12 deficiency, defined as an increase in the MMA/creatinine ratio and TH normalized with B12, is highly prevalent among elderly subjects and may occur in absence of clinical and/or analytical manifestations. Given the widespread recommendation of quantitating MMA and TH for the diagnosis of borderline cases of vitamin B12 deficiency, such disturbance may occur in clinically and biochemically normal subjects. Thus, a special caution should be exerted, given the existing comorbidity in advanced ages, before attributing B12 deficiency to a condition which may be the expression of another concomitant condition.