Monitoring the Post-op Bariatric Surgery Patient

David A. Johnson, MD


February 13, 2012


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The Obesity Dilemma

Hello. I'm Dr. David Johnson, Professor of Medicine and Chief of Gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia. On this edition of GI Common Concerns -- Computer Consult, I would like to talk about a very problematic issue: the postoperative care of patients who have had bariatric surgery.

Obesity is a tremendous problem. By 2020, it is expected that two thirds of the US population will be either overweight or obese. Obesity accounts for, at present, more than 225,000 bariatric surgeries every year. It is estimated that it costs the United States more than $100 billion per year for the direct and indirect costs of obesity-related complications.

The Post-op Bariatric Patient

Whether you are a gastroenterologist, an internist, an obstetrician/gynecologist, or a primary care provider, these patients are coming through your pathways because obesity is such a prevalent disease and bariatric surgery is a common operation. I want to alert you to several key issues, because these patients are cured for the most part of some of their obesity-related problems (hopefully with a good outcome), but the metabolic and nutritional consequences in these patients are easy to neglect without a very comprehensive plan for postoperative surgical management. This doesn't mean just seeing them at 3 and 6 months postoperatively; it means lifelong intervention and monitoring.

You may be the only responsible healthcare provider if patients have been disengaged from their surgeons because their wounds are healed and their surgery is complete. However, these patients can present with profound complications -- neurologic complications, life-threatening complications, and cardiomyopathy -- a number of things that, if recognized, can be treated or, if proactively monitored, can be prevented with appropriate intervention. What are we looking for during follow-up with these patients?

Routine Monitoring

The most definitive operation for obesity is a Roux-en-Y bypass, but you may be seeing a number of permutations of this procedure in your community. The Roux-en-Y bypass basically diverts the duodenum and proximal jejunum, essentially creating a malabsorptive syndrome.

Every patient who has had bariatric surgery whom I follow automatically is prescribed a chewable multivitamin twice daily. The chewables are best because these patients have a very short gastric pouch (generally, 30 mL), and you want to give every opportunity for the pill to dissolve and potentially be absorbed in the short, foreshortened intestine. In addition to the chewable vitamin twice daily, these patients should take elemental calcium 1.2 g/day. These 2 supplements are "nonnegotiable" -- every one of those patients goes on these formulations if they are not already taking them.

In following these patients, it is very important to do routine monitoring. We follow these people at 3 and 6 months after their surgery and routinely measure a comprehensive metabolic profile and serum lipids. We measure glycosylated hemoglobin and fasting blood glucose and monitor these laboratory tests over the course of sequential yearly evaluations.

At 6-month intervals for the first 3 years, we measure and look for micro- and macronutrient deficiencies, particularly deficiencies of vitamins B12, A, and D. These are very common in the post-bariatric surgery patient.

The most common things that we see in these patients during the first year are:

  • Iron deficiency (10%);

  • Vitamin B12 deficiency (10%);

  • Folate deficiency (10%); and

  • Vitamin D deficiency (>50%).

These are the 4 nutritional deficiencies for which we monitor these patients.

When patients return for follow-up care at 6 months, we look for the consequences of malabsorption and check not only their vitamin levels but also their zinc and copper levels. We also check the metabolic profile and obtain a 24-hour urinary calcium as a measure of bone degradation and hyperparathyroidism resulting from vitamin D malabsorption and hypocalcemia.

Thiamine Deficiency

An important deficiency that must be remembered, even if you forget everything else, is thiamine. Thiamine deficiency is associated with a number of neurologic consequences, including the classic Wernicke encephalopathy. Thiamine deficiency is not uncommon in patients who have had bariatric surgery. It can occur from malabsorption, but it also can occur from a secondary bacterial overgrowth. Many cases of thiamine deficiency have been reported in patients whose thiamine levels do not respond to thiamine supplementation. The standard thiamine supplementation is 100 mg twice daily. If the patient has a recognizably low thiamine level and is not responding to treatment, start thinking about small-bowel overgrowth. Several patients have been described, primarily from the group at the Washington Hospital Center,[1] in whom bacterial overgrowth has been treated and then their thiamine levels normalized.

Don't neglect to obtain thiamine levels in these patients. Note that whole-blood thiamine must be tested in postoperative bariatric surgery patients. Don't just check the box for a thiamine level without ensuring that the test is for whole-blood thiamine, which is more representative. Results can be misleading if you order a regular serum thiamine level.

The clinical scenario for thiamine deficiency is the postoperative bariatric surgery patient who presents to the emergency department with nausea and vomiting. Patients with those hallmark symptoms should be given thiamine before they are given any glucose, because you can precipitate Wernicke' encephalopathy and these patients are very susceptible to that. Be aware of that, and don't forget thiamine deficiency in patients with postoperative nausea and vomiting.

Dermatologic Manifestations

With respect to other vitamin deficiencies, especially those of vitamins A and E, copper, and zinc, we should be thinking about dermatologic manifestations. Dermatologic presentations after bariatric surgery should be considered not just a minor problem, but potentially an indicator of malabsorption. Always think about copper and zinc deficiency, and obtain zinc levels routinely every 6 months for the first 3 years and then yearly after that. Acrodermatitis enteropathica is a classic rash for zinc deficiency.

These patients can also have a malabsorption of essential fatty acids. Xerosis with dry scaly skin in a bariatric patient may be more than a bit of dry scaly skin; it may be an indicator of a more significant malabsorptive process. Both linoleic and linolenic acid can be affected. Canola oil, flaxseed oil, and soybean oil can be supplemented very easily and potentially bring the patient's levels of these essentially fatty acids back to normal.

Neurologic Symptoms

Neurologic symptoms or postoperative peripheral neuropathy occurs in approximately 44% of post-bariatric surgery patients. Think about deficiencies of vitamin B12, zinc, vitamin E, and thiamine. These are nutritional elements that are important to measure.

Visual Disturbances

If you have a patient who is presenting with some type of visual disturbance, think about what causes peripheral vision changes and night blindness: it's vitamin A deficiency.

Vitamin E deficiency can create visual problems as well, as can thiamine deficiency, when patients experience ophthalmoplegia associated with Wernicke encephalopathy.

You Might Be the Only One Watching

Remember that you may be the only healthcare provider who is thinking about the multisystem disease manifestations of vitamin or micro- and macronutrient deficiencies in patients who have had bariatric surgery. There is a tremendous opportunity to prevent complications and to recognize complications when they present to you, but there is also a tremendous opportunity to miss these complications if you are not monitoring these patients regularly.

Let me recap. At 3 and 6 months, measure:

  • Comprehensive metabolic panel;

  • Glycosylated hemoglobin;

  • Lipid panel; and

  • Fasting blood glucose.

Every 6 months, measure:

  • Vitamin B12;

  • Folate;

  • Vitamin D (1,25-hydroxyvitamin D);

  • 24-hour urinary calcium;

  • Zinc;

  • Copper; and

  • Thiamine.

You can prevent and recognize a number of nutritional complications in these patients. Hopefully, this dialogue on GI Common Concerns -- Computer Consult will give you some insight into that next time you are faced with a post-bariatric surgery patient.

I'm Dr. David Johnson. Thanks again for listening.