Frequency of laboratory testing among gastric bypass patients

Long-term laboratory monitoring is recommended after gastric bypass surgery to prevent the development of micronutrient deficiencies. The objective of this study was to characterize patterns of laboratory monitoring after surgery.

We used a large insurance claims database to assess the frequency of laboratory testing after gastric bypass surgery. We assessed the tests recommended by an expert panel on bariatric surgery, including tests recommended routinely as well as second-line tests for specific clinical scenarios (e.g., tests for anemia when iron deficiency is not present).

With the exception of testing for diabetes, most gastric bypass patients did not undergo routine laboratory testing in the first year after their surgery, ranging from 54% (electrolytes) to 95% (zinc). However, for first-line tests, significantly more gastric bypass patients underwent testing in the first year,compared with gastric banding patients. Differences in testing frequency between gastric bypass and gastric banding patients were larger for tests of micronutrient deficiency than for common metabolic panels and complete blood counts. For second-line tests, much smaller percentages of both groups of patients underwent testing, either in the first year or after year 1.

Patients undergoing gastric bypass do not routinely undergo recommended laboratory tests, although they are undergoing more monitoring than gastric banding patients. Efforts must be made by patients, surgeons, and primary care providers to ensure that routine testing is done to lower the risk of adverse health outcomes.