Abstract
Bariatric surgery is an effective treatment for patients with morbid obesity. However, as safe and common as bariatric procedures have become, multiple complications can still result. These complications vary depending on the type of procedure performed (malabsorptive or restrictive) and are often nutritional derangements from the altered malabsorptive surface of the gastrointestinal tract and decreased capacity of the stomach. Deficiencies in vitamin D after malabsorptive procedures such as the Roux-en-Y gastric bypass can result in subsequent hypocalcemia and bone demineralization, and anemias can also present after surgery from inadequate vitamin B12 and iron absorption. Because of the prevalence of these deficiencies, baseline micronutrient testing and postoperative screening are recommended in many cases. Additionally, supplemental treatment often requires higher doses than those recommended for healthy adults. The purpose of this narrative review is to outline the various nutrient deficiencies that can result from bariatric procedures and report previously-published recommendations for screening and medical treatment of patients with these deficiencies. This review is directed toward primary care practitioners because of their unique position in delivering continuity of care and the frequency with which they will encounter patients who have undergone bariatric surgery and are seeking counseling regarding weight loss modalities.
Highlights
Bariatric surgery is an effective treatment for patients with morbid obesity
Deficiencies in vitamin D after malabsorptive procedures such as the Roux-en-Y gastric bypass can result in subsequent hypocalcemia and bone demineralization, and anemias can present after surgery from inadequate vitamin B12 and iron absorption
Nutritional derangements are common, longterm complications of bariatric procedures resulting from obesity-related malnourishment, noncompliance with postoperative supplementation, and the malabsorptive nature of the procedures.[7,8,9]
Summary
We performed an electronic search through PubMed/ MEDLINE and the Free Medical Journals online database in November 2017 using the keywords “bariatric surgery complications” and “adverse effects.” Our search yielded 604 results. Multiple guidelines recommend baseline and postoperative evaluation for vitamin B12 deficiency in all bariatric surgery patients and annually for LSG or RYGB patients.[6,9] To maintain normal B12 levels, oral supplementation with crystalline vitamin B12 1000 μg/day (at least 350-400 μg/day)[6] is indicated within 6 months of surgery to prevent the development of deficiencies.[13] Other courses of B12 replacement include 500 to 1000 μg weekly intranasally or 1000 to 3000 μg every 6 to 12 months of parenteral B12 if oral or intranasal routes are insufficient.[6,13] Folate deficiencies are another cause of anemia in postoperative bariatric surgery patients, typically seen less often because of the high amounts of folic acid fortified foods and vitamin supplementation available.[4,9] If present, the deficiency is most likely secondary to decreased intake of folate-rich foods rather than malabsorption.[5] Diagnosis of a megaloblastic anemia caused by vitamin B12 or folate would include an increased homocysteine level.[9] Megaloblastic anemia caused by either vitamin B12 or folate deficiencies can be differentiated by measurement of a plasma methylmalonic acid level, which is elevated in a patient with vitamin B12 deficiency and normal when folate is deficient.[9] Nutritional supplementation of folate should be at least 400 μg/day.[13,15]. Mild: Protein supplementa- Albumin/pre-albumin tion - g/day measured preopera-
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