Nutritional deficiencies in gastric bypass patients; incidence, time of occurrence and implications for post-operative surveillance.

BACKGROUND: Post-operative nutritional deficiencies are a common complication following bariatric surgery. The incidence and time of occurrence are not clear, and the efficacy of supplementation remains questionable. Clear guidelines for nutritional follow-up and counselling are needed.
METHODS: Preoperative and post-operative deficiencies were determined in a group of 427 gastric bypass patients. The predictive value of preoperative laboratory findings for the development of post-operative deficiencies, the time of occurrence and the effect of supplementation of common deficiencies was studied.
RESULTS: Most common preoperative deficiencies were of folic acid (21.3%), vitamin D3 (17.5%) and iron (21.8%). Post-operative, a significant increase in the number of patients with anaemia and deficiencies of ferritin and vitamin B12 was found. Most deficiencies occur between 12 and 15 months post-operatively, but vitamin D3 deficiency occurs significantly earlier at 9.7 months. A preoperative iron, folic acid or ferritin deficiency results in a significant higher risk for developing a post-operative deficiency despite supplementation, and ferritin deficiency occurs significantly earlier in these patients. Oral treatment of post-operative vitamin B12 and vitamin D3 deficiencies was successful in more than 80% of the patients in contrast to oral treatment of anaemia which was only successful in 62.5% of the patients.
CONCLUSION: Our study emphasizes the importance of preoperative assessment and treatment of nutritional deficiencies in morbidly obese patients undergoing gastric bypass surgery. Despite limited efficacy, post-operative oral supplementation should be encouraged as it decreases the incidence of deficiencies.