Anemia After Bariatric Surgery: More Than Just Iron Deficiency

Abstract

Bariatric surgery for morbid obesity is rapidly gaining popularity. Restrictive and/or malabsorptive surgical interventions result in dramatic weight loss with significantly decreased obesity-related morbidity and mortality. Anemia, which may affect as many as two-thirds of these patients, is of concern and generally thought to be caused by iron deficiency. Although iron deficiency in this population may be frequent given pouch hypoacidity, defunctionalized small bowel, and red meat intolerance, it may not account for all anemias seen. First, there is increasing evidence that obesity creates a state of chronic inflammation. Both iron deficiency anemia and anemia of chronic inflammation present with low serum iron levels. Most studies reporting anemia after bariatric surgery lack serum ferritin determinations so that the relative contribution of inflammation to anemia cannot be assessed. Second, a significant number of anemias after bariatric surgery remain unexplained and may be attributable to less frequently seen micronutrient deficiencies such as copper, fatsoluble vitamins A and E, or an imbalance in zinc intake. Third, although deficiencies of folate and vitamin B(12) are infrequent, study observation periods may be too short to detect anemia attributable to vitamin B(12) deficiency because vitamin B(12) storage depletion takes many years. This review is intended to increase awareness of the mechanisms of anemia above and beyond iron deficiency in the bariatric patient and provide healthcare providers with tools for a more thoughtful approach to anemia in this patient population.

Overview of bariatric surgery for the physician

“…5,6,9,10,25 Long-term complications include internal hernias, anastomotic stenoses, marginal ulceration, fistulae, diarrhoea, dumping syndrome, gallstones, emotional disorders and nutritional deficiencies. 5,6,13,15,20,[25][26][27] Patients with LAGB can experience port problems, stomal obstruction, band slippage/erosion, pouch dilation, gastro-oesophageal reflux and oesophageal dilation. 5,13,19,25 Malnutrition is a concern with BPD with or without DS.…”

“…Anaemia 20,27 After bariatric surgery, patients are prone to iron deficiency because of intestinal bypass, pouch hypoacidity and intolerance of red meat. Obesity creates a state of chronic inflammation that to changes in body weight.…”

Anemia attributed to vitamin B6 deficiency in post-pancreaticoduodenectomy patients

“…Vitamin B6 malabsorption can theoretically occur in bariatric patients undergoing the roux-en-Y procedure as well, a patient population in which anemia is also prevalent. A significant proportion of anemias in bariatric patients remain unexplained [12], and we speculate that some are related to vitamin B6 deficiency. In conclusion, post-PD patients should be monitored for micronutrient deficiencies including vitamin B6, and supplementations should be carried out when necessary.…”

Should bariatric surgery be performed in adolescents?

“…The suggestion that surgery should be postponed until adulthood in eligible adolescents is reached does not appear evidence based as rates of significant nutritional abnormalities generally appear comparable between adolescent and adult groups after bariatric surgery ( Table 1). Note that although post-operative hypoferritinemia has been reported to be common in adolescents (22), iron stores actually increase after bariatric surgery in adolescents (27), suggesting the reversal of chronic inflammatory processes may be contributory to falling ferritin levels (115).…”