What annual labs should be drawn for a patient with a history of bariatric surgery?

Annual Laboratory Monitoring After Bariatric Surgery

Patients with a history of bariatric surgery should undergo annual laboratory monitoring that includes complete blood count, ferritin, folate, vitamin B12, vitamin D, calcium, renal function tests, liver function tests, and additional micronutrients based on the specific bariatric procedure performed. 1, 2

Core Annual Laboratory Tests for All Bariatric Surgery Patients

• Complete blood count (CBC) to monitor for anemia, which occurs in up to 50% of post-gastric bypass patients 1, 2
• Ferritin levels to assess iron stores, with a target of at least 50 μg/L (higher in patients with chronic inflammation) 1, 3
• Folate levels to detect deficiency due to malabsorption and poor dietary intake 1, 2
• Vitamin B12 levels to monitor for deficiency, which affects up to 61.8% of patients and can cause irreversible neurological damage 1, 2
• Vitamin D (25-hydroxyvitamin D) levels, which should be maintained above 75 nmol/L for optimal bone health 1, 2
• Calcium levels to prevent bone demineralization 1, 2
• Renal function tests (urea, creatinine, electrolytes) to assess kidney function and hydration status 1
• Liver function tests to document changes in non-alcoholic fatty liver disease (NAFLD) and monitor for hypoalbuminemia 1
• Zinc levels to detect deficiency, which affects up to 40.5% of patients and can cause poor wound healing, hair loss, and taste changes 2
• Copper levels, especially when supplementing zinc, as they compete for absorption 2

Additional Tests Based on Procedure Type

For Malabsorptive Procedures (BPD/DS, Long-Limbed Bypass)

• Fat-soluble vitamins (A, E, K) should be monitored annually 2
• Selenium levels if symptoms of unexplained anemia, cardiomyopathy, or chronic diarrhea are present 2
• Protein levels to assess for protein-calorie malnutrition 4

For Patients with Pre-existing Conditions

• HbA1c for patients with preoperative diabetes to monitor improvement 1, 2
• Lipid profile for patients with preoperative dyslipidemia 1, 2

Monitoring Schedule

The British Obesity and Metabolic Surgery Society (BOMSS) recommends the following monitoring schedule:

• First year post-surgery: Check labs at 3,6, and 12 months 1
• After first year: Annual monitoring for life 1, 5

Special Considerations

• For pregnant women who have had bariatric surgery: More frequent monitoring (every trimester) of ferritin, folate, vitamin B12, calcium, vitamin D, and vitamin A 1, 2
• For adolescents: Regular nutritional monitoring due to ongoing growth and development 1, 2
• For patients with unexplained anemia: Consider checking protein, zinc, copper, and selenium levels 1, 2

Common Pitfalls to Avoid

• Failing to check vitamin B12 when prescribing high-dose folic acid, as folate can mask B12 deficiency 2
• Not monitoring zinc and copper simultaneously, as supplementation of one affects levels of the other 2
• Overlooking the possibility that megaloblastic anemia from B12 deficiency can be masked by concurrent iron deficiency 6
• Assuming standard multivitamins alone are sufficient to prevent nutritional deficiencies 6, 5
• Discontinuing monitoring after the initial 2-year follow-up period, when lifelong monitoring is recommended 5

Long-term Follow-up Recommendations

Lifelong nutritional monitoring is essential for all patients who have undergone bariatric surgery to prevent, detect, and manage nutritional deficiencies that can lead to serious health complications 1, 5. Shared care models between bariatric centers and primary care providers are recommended to ensure appropriate long-term monitoring 5.