Bariatric Surgery Biochemical Monitoring and Micronutrient Replacement Clinical Practice Guidelines (BOMSS, 2020)

British Obesity and Metabolic Surgery Society

This is a quick summary of the guidelines without analysis or commentary. For more information, go directly to the guidelines by clicking the link in the reference.

November 17, 2020

In November 2020, the British Obesity and Metabolic Surgery Society published guidelines for biochemical monitoring and micronutrient replacement in patients who undergo bariatric surgery.[1]

Preoperative Nutritional Assessment

A comprehensive nutritional assessment is recommended for all patients who are planning to undergo bariatric surgery. Anemia and decreased levels of ferritin, folate, vitamin B12, and vitamin D are the most common deficiencies in adults and adolescents with severe and complex obesity.

Include the following tests in the preoperative assessment:

  • A complete blood cell (CBC) count including hemoglobin

  • Measurement of ferritin, folate, and vitamin B12 levels

  • Measurement of serum 25-hydroxyvitamin D and calcium levels and serum/plasma parathyroid hormone levels

  • Measurement of hemoglobin A1c (HbA1c) level

  • Lipid profile

  • Liver and kidney function tests

Consider assessing serum vitamin A, zinc, copper, and selenium levels in patients who are scheduled for malabsorptive procedures, such as biliopancreatic diversion with duodenal switch (BPD/DS), or who have a suspected deficiency. Routine screening for thiamine or magnesium deficiency is not recommended.

Treat any nutritional deficiencies before bariatric surgery is performed.

Postoperative Care and Monitoring

Lifelong follow-up after bariatric surgery is necessary to ensure that nutritional requirements are met and to detect deficiencies and other complications. The following tests are recommended at 3, 6, and 12 months after the procedure and at least once a year thereafter:

  • Kidney and liver function tests

  • A CBC count and measurement of serum ferritin levels

  • Measurement of serum folate, vitamin B12, vitamin D, and calcium levels

Parathyroid hormone levels should be checked if it was not done before surgery.

Measure serum vitamin A, vitamin E, and vitamin K1 and PIVKA-II (protein induced by vitamin K absence or antagonism) levels at regular intervals after malabsorptive procedures, such as BPD/DS, or if symptoms of deficiency occur.

Monitor serum zinc, copper, and selenium levels after sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), or BPD/DS. Routine monitoring of magnesium levels is not necessary.

Keep in mind the potential risk of severe thiamine deficiency in patients who have undergone bariatric surgery. If a deficiency is suspected, initiate oral or intravenous treatment without delay.

Monitor HbA1c and lipid levels in patients with preoperative diabetes and dyslipidemia, respectively.

Vitamin and Mineral Supplementation

A complete daily multivitamin and mineral supplement, which includes thiamine, iron, folic acid, selenium, zinc, and copper, is recommended for all patients who have had bariatric surgery.

In addition to a multivitamin and mineral supplement, prescribe elemental iron and intramuscular vitamin B12 injections for patients who have undergone SG, RYGB and malabsorptive procedures, such as BPD/DS. Such patients may also require supplementation with vitamins A and E, as well as zinc, copper, and selenium.

The optimal calcium intake for patients who have undergone bariatric surgery is not known. Encourage consumption of dietary calcium, which is more bioavailable than supplemental calcium.

For more information, please go to Bariatric Surgery and Obesity.

For more Clinical Practice Guidelines, please go to Guidelines.


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