Elevated Methylmalonic Acid and Total Homocysteine Levels Show High Prevalence of Vitamin B₁₂ Deficiency after Gastric Surgery

1 March 1996 | Volume 124 Issue 5 | Pages 469-476

Objective: To determine the prevalence of vitamin B₁₂ deficiency in patients who have had gastric surgery.

Design: Cross-sectional study.

Setting: Philadelphia Veterans Affairs Medical Center.

Participants: 61 patients who had had gastric surgery and 107 controls.

Measurements: Serum levels of vitamin B₁₂, folate, methylmalonic acid, and total homocysteine measured before and after treatment in participants with vitamin B₁₂ deficiency. Vitamin B₁₂ deficiency was defined as one of the following: 1) a serum vitamin B₁₂ level less than 221 pmol/L and an elevated methylmalonic acid level; 2) a serum vitamin B₁₂ level less than 221 pmol/L and an elevated total homocysteine level that decreased with vitamin B₁₂ treatment; or 3) in patients unavailable for treatment, a serum vitamin B₁₂ level less than 221 pmol/L, a folate level greater than 9 nmol/L, and an elevated total homocysteine level.

Results: Study patients and controls were similar in age, sex, and racial distribution. Nineteen patients (31%) and 2 controls (2%) had vitamin B₁₂ deficiency (P < 0.001). Twelve (63%) of the 19 vitamin B₁₂-deficient patients had elevated total homocysteine levels. In all participants with vitamin B₁₂ deficiency who received treatment (15 of 21), methylmalonic acid and total homocysteine levels decreased substantially, confirming the deficiency before treatment.

Conclusion: Patients who have had gastric surgery have a high prevalence of vitamin B₁₂ deficiency. Prompt recognition and treatment of the deficiency with resultant normalization of elevated total homocysteine and methylmalonic acid levels may prevent the development of cardiovascular, hematologic, and neurologic abnormalities. Our data support both frequent screening and vitamin B₁₂ replacement therapy in patients who have had gastric surgery and have serum vitamin B₁₂ levels less than 221 pmol/L.

Author and Article Information

From Philadelphia Veterans Affairs Medical Center, Medical College of Pennsylvania and Hahnemann University, Philadelphia College of Pharmacy and Science, and Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; and University of Colorado Health Sciences Center, Denver, Colorado.
Grant Support: By Department of Health and Human Services research grants DK-21365(RHA), AG0983(SPS), and AG00532 (AES) from the National Institutes of Diabetes and Digestive and Kidney Diseases and the National Institute on Aging and by The Howard Heinz Endowment to the Medical College of Pennsylvania. The University of Colorado and two of the authors, Robert H. Allen and Sally P. Stabler, have applied for patents covering various aspects of the assays for methylmalonic acid and homocysteine.
Requests for Reprints: Anne E. Sumner, MD, Medical College of Pennsylvania, 3300 Henry Avenue, Philadelphia, PA 19129.