Prevalence of thiamine deficiency is significant in patients undergoing primary bariatric surgery

Background: Patients undergoing metabolic and bariatric surgery are prone to developing micronutrient deficiencies, necessitating life-long nutritional supplementation and monitoring. Historically, these deficiencies were thought to be driven by postsurgical changes in absorption. Recent data, though, have demonstrated that obesity alone is also associated with micronutrient deficiencies. Thiamine deficiency, in particular, can lead to permanent neurologic deficits.

Objective: Identify thiamine deficiency prevalence within the preoperative metabolic and bariatric surgery patient population.

Setting: Single institution academic medical center.

Methods: A retrospective review of deidentified data was examined that included whole blood thiamine measured from consecutive patients from April 2018 to June 2019 (n = 346). Cohort characteristics were assessed including age, operation, preoperative weight, and race/ethnicity. The majority of the cohort were women (83%) with an average age of 44.9 years. Racial representation included White/Caucasian (73%) and Black (21%), while operations included Roux-en-Y gastric bypass (58%), sleeve gastrectomy (31%), and revisions (10%).

Results: Thiamine concentration was normally distributed with a mean of 144 nM. Overall, 3.5% of patients had thiamine concentrations below the lower limit of normal of <70 nM, while 35 additional patients (14%) were at risk for thiamine deficiency with concentrations <100 nM. On the average, these patients were of similar age and were all undergoing primary procedures (50% gastric bypass, 50% sleeve gastrectomy). Regression methods demonstrated that patients with thiamine deficiency tended to be females with higher body mass index, even after controlling for sex, height, and preoperative weight. After covariate adjustment, male sex and increasing height were both associated with higher thiamine concentration.

Conclusion: Previously quoted rates of thiamine deficiency in the preoperative patient are variable, but we describe a significant number of patients with, or at risk of, thiamine deficiency. Male sex and increasing height are likely associated with increased skeletal muscle mass, which is enriched with thiamine. Routine thiamine measurement, either preoperatively or at the time of surgery, is warranted given its limited stores within the body and potential catastrophic complications associated with acute or chronic deficiency.