Nutritional Deficiencies in Patients with Severe Obesity before Bariatric Surgery: What Should Be the Focus During the Preoperative Assessment?

BACKGROUND: Nutritional deficiencies are a well-recognized long-term complication following bariatric surgery. The presence of preoperative deficiencies has been shown to be predictive of postoperative deficiencies. OBJECTIVE: The aim of the study was to investigate the prevalence of micronutrient deficiency in a large sample of patients with severe obesity preoperatively, and to determine whether such deficiencies may be related to patient's sex, body mass index, or ethnic subgroup. DESIGN: A cross-sectional study of data collected at the time of the preoperative evaluation. PARTICIPANTS/SETTING: Data were collected during the preoperative evaluation of 872 bariatric surgery candidates in a university hospital in Israel between 2011 and 2018. The patients were 72.9% women, with a mean age of 37.9±12.1 years and mean body mass index of 42.4±4.7 MAIN OUTCOME MEASURES: Nutritional deficiencies according to blood assays. Data on anthropometrics, comorbidities, and demographic characteristics was also collected. STATISTICAL ANALYSES: Baseline differences between patient subgroups were analyzed using independent-samples t test, analysis of variance, or χ2 test. RESULTS: Deficiencies of vitamin D, iron, folate, vitamin B-12, elevated parathyroid hormone and low transferrin saturation were present in 75.2%, 42.6%, 28.5%, 8.5%, 35.5%, and 70% of patients, respectively. Nutritional deficiencies were significantly more common among women compared with men for iron (45.9% vs 33.5%; P=0.002), low transferrin saturation (77.7% vs 44.6%; P<0.001), vitamin D (77.5% vs 69.2%; P=0.019) and elevated parathyroid hormone level (39.5% vs 22.9%; P=0.002). Iron, transferrin saturation, and vitamin D deficiencies were more prevalent in Arab patients compared with Jewish patients: 59.6% vs 36%; P<0.001, 80.2% vs 62.8%; P=0.003, and 85.1% vs 71.6%; P<0.001, respectively. Vitamin D and iron deficiency were more common among higher body mass index subgroups (P=0.004 and P=0.040, respectively). CONCLUSIONS: The results indicate a high prevalence of nutritional deficiencies, mainly of iron and vitamin D in bariatric surgery candidates. Patients at higher risk for nutritional deficiencies include those with higher body mass index, women, and Arabs.

Nutritional Management for Chronic Kidney Disease Patients who Undergo Bariatric Surgery: A Narrative Review.

Bariatric surgery (BS) may be effective for chronic kidney disease (CKD) patients by reducing microalbuminuria and proteinuria, and by facilitating their meeting inclusion criteria for kidney transplantation. However, nutritional management for this population is complex and specific guidelines are scarce. A literature search was performed to create dietetic practice for these patients based on the most recent evidence. For the purposes of nutritional recommendations, we divided the patients into 2 subgroups: 1) patients with CKD and dialysis, and 2) patients after kidney transplantation. Before surgery, nutritional care includes nutritional status evaluation and adjusting doses of supplements to treat deficiencies and daily nutrient intake according to the dietary restrictions derived from kidney disease, including quantities of fluids, protein, phosphorus, potassium, and vitamins. After BS, these patients are at major risk for lean body mass loss, malnutrition and dehydration because of fluid restriction and diuretics. Postoperative nutritional recommendations should be carefully tailored according to CKD nutritional limitations and include specific considerations regarding protein, fluids, and supplementation, in particular calcium, vitamin A, and vitamin D. Nutritional management of CKD and kidney transplant patients undergoing BS is challenging and future studies are required to establish uniform high-level evidence-based guidelines.