Hematological Disorders following Gastric Bypass Surgery: Emerging Concepts of the Interplay between Nutritional Deficiency and Inflammation

Abstract

Obesity and the associated metabolic syndrome are among the most common and detrimental metabolic diseases of the modern era, affecting over 50% of the adult population in the United States. Surgeries designed to promote weight loss, known as bariatric surgery, typically involve a gastric bypass procedure and have shown high success rates for treating morbid obesity. However, following gastric bypass surgery, many patients develop chronic anemia, most commonly due to iron deficiency. Deficiencies of vitamins B1, B12, folate, A, K, D, and E and copper have also been reported after surgery. Copper deficiency can cause hematological abnormalities with or without neurological complications. Despite oral supplementation and normal serum concentrations of iron, copper, folate, and vitamin B12, some patients present with persistent anemia after surgery. The evaluation of hematologic disorders after gastric bypass surgery must take into account issues unique to the postsurgery setting that influence the development of anemia and other cytopenias. In this paper, the clinical characteristics and differential diagnosis of the hematological disorders associated with gastric bypass surgery are reviewed, and the underlying molecular mechanisms are discussed.

Obesity-related immune responses and their impact on surgical outcomes

“…Deficiencies of vitamins B1, B12, folate, A, K, D, and E and copper potentially causing cytopenia have been reported. 45 These findings underscore the importance of oral supplementation, at least in the early period after the procedure.…”

Copper deficiency, a new triad: anemia, leucopenia, and myeloneuropathy

“…It can take several years before the body copper stores are depleted [10]. Therefore, for patients with hematological abnormalities (anemia, neutropenia, myelodysplasia) and especially neurological deficits resembling vitamin B 12 deficiency after gastric surgery, deficiency of copper should be considered in the differential diagnosis [22]. …”

Evaluation of Macrocytic Anemias

“…Bariatric surgery can result in malabsorptive disorders, including poor absorption of copper, iron, and B12. 48 Deficiency of copper can result in either macrocytic, microcytic, or normocytic anemia. 49 As malabsorption of one or more of these nutrients can result in either a microcytic anemia (iron), macrocytic anemia (B12), or a mixed picture (two or more of these nutrients), the evaluation of anemia in post-bariatric surgery patients should include testing for deficiencies of all of these nutrients.…”

“…Ring sideroblasts have also been observed in these patients. 48,49 If there is concomitant B12 deficiency, megaloblastic changes can also occur in the marrow, further complicating interpretation of the marrow findings.…”