From the Guidelines
Annual laboratory tests for bariatric surgery patients should include a comprehensive metabolic panel, complete blood count, lipid panel, hemoglobin A1C, vitamin B12, folate, iron studies (including ferritin, iron, TIBC), vitamin D, parathyroid hormone, and fat-soluble vitamins (A, E, K). These tests are essential because bariatric procedures alter the digestive anatomy, potentially leading to nutrient malabsorption and metabolic changes 1. The comprehensive metabolic panel monitors liver and kidney function, while the complete blood count screens for anemia, which is common after gastric bypass or sleeve gastrectomy. Vitamin and mineral deficiencies are particularly concerning, with B12, iron, vitamin D, and calcium being most frequently affected.
According to the British Obesity and Metabolic Surgery Society guidelines, patients undergoing bariatric surgery should have a comprehensive nutritional assessment prior to surgery, including checks for haematinics, vitamin D, calcium, and parathyroid hormone levels 1. The guidelines also recommend checking full blood count, including haemoglobin, ferritin, folate, and vitamin B12 levels, as well as serum 25-hydroxyvitamin D levels and serum/plasma parathyroid hormone levels.
Patients who have undergone malabsorptive procedures like biliopancreatic diversion or duodenal switch require more vigilant monitoring and may need additional tests for zinc, copper, and selenium 1. Laboratory testing should be conducted more frequently (every 3-6 months) during the first two years post-surgery, then annually thereafter if results remain stable, as recommended by the clinical practice guidelines for adult bariatric surgery patients 1. Prompt identification and correction of deficiencies can prevent serious complications like neuropathy, osteoporosis, and anemia.
Key laboratory tests to check annually include:
- Comprehensive metabolic panel
- Complete blood count
- Lipid panel
- Hemoglobin A1C
- Vitamin B12
- Folate
- Iron studies (including ferritin, iron, TIBC)
- Vitamin D
- Parathyroid hormone
- Fat-soluble vitamins (A, E, K) Additional tests may be necessary for patients who have undergone malabsorptive procedures, such as zinc, copper, and selenium levels 1.
From the Research
Bariatric Annual Labs
To check for various health conditions after bariatric surgery, the following annual labs are recommended:
- Complete Blood Count (CBC) to assess cardiovascular and metabolic diseases, including:
- White blood cell (WBC) count
- Neutrophil-to-lymphocyte ratio (NLR)
- Hemoglobin (Hb) level
- Mean corpuscular volume (MCV)
- Red cell distribution width (RDW)
- Platelet count
- Mean platelet volume (MPV)
- Platelet-to-lymphocyte ratio (PLR) 2
- Other tests may be recommended based on individual patient needs and medical history
Limitations of Current Evidence
There is limited direct evidence on the specific annual labs required for bariatric patients. However, studies suggest that CBC components can be useful markers to predict cardiovascular disease and metabolic diseases 2. Other studies are not directly relevant to this question, focusing on topics such as enzyme isolation and cancer therapy 3, 4