Biological follow-up of bariatric surgery

In France, more than eight million adults are classed as obese, i.e. 17% of the population. Officially recognised as a pathology by the World Health Organisation (WHO) in 1998, obesity is multi-factorial: an unbalanced diet, sedentary lifestyle, psychosocial fragility, environmental factors, trauma, and family susceptibility can all play a part.

Today, obesity can be managed and excellent results achieved through bariatric surgery, both in terms of weight loss and considerable regression of comorbidities. In addition to its direct effect, this surgery also helps the patient to modify their eating behaviour and adopt a new lifestyle that contributes to maintaining weight loss over time.

In 2009, the HAS issued precise recommendations concerning the surgical management of obesity (1). Since then, European guidelines have been published (2) and the French Society (SOFFCO) has recently published good practice recommendations for the nutritional follow-up of patients after bariatric surgery (3).

Managing a patient undergoing bariatric surgery involves the participation of a multidisciplinary team, in collaboration with the attending physician.

WHY OPERATE?

Obesity is a risk factor for mortality, which increases with body mass index (BMI). The complications are metabolic and organic: type 2 diabetes, hypertension, sleep apnea syndrome, cardiovascular disease, dyslipidemia, osteoarticular disease, infertility, increased risk of cancer, reduced life expectancy, etc.

Medical treatments have not proven to be effective over time, and some are even dangerous. The literature shows that in the long term, surgery is more effective than medical treatment in terms of weight loss, regression of co-morbidities and improved life expectancy. In fact, patients are actively requesting it.

Following bariatric surgery, the typical pattern is for a patient to achieve maximum weight loss after one year. This is often followed by a limited weight regain, but at 10-15 years post-surgery, the weight loss is maintained.

At the same time, metabolic complications are reduced (resolution of diabetes in 80 to 90% of cases, depending on the series), as is mortality in the long term; finally, there is a very clear and prominent improvement to quality of life, both pre-operatively in the patient’s decision, and post-operatively, including in the long-term follow-up. More than a weight loss surgery, bariatric surgery is a metabolic surgery, demonstrated by the decrease in the consumption of antihypertensive, antidiabetic and hypolipidemic drugs after five years.

WHICH TECHNIQUE SHOULD BE USED?

 The three most commonly performed bariatric procedures in France are :

• sleeve gastrectomy (longitudinal gastrectomy),
• adjustable perigastric ring,
• and Roux-en-Y gastrojejunal bypass (gastric or intestinal bypass).

Sleeve gastrectomy (SG) and adjustable perigastric bands are restrictive procedures, and having a bypass is a restrictive procedure with malabsorption.

The choice of one procedure over another depends on the cause of the obesity, the patient’s ability to adapt to new dietary measures, the weight loss objectives, the patient’s profile (age, level of education, lifestyle habits, etc.), their medical and surgical history, current treatments, a possible desire for pregnancy, etc. (4). At the end of 2017, sleeve gastrectomy was performed twice as often as bypasses, and the ring procedure was obserably declining in popularity (5). Other techniques have recently been evaluated by the HAS (5) and some of them are likely to spread in France; namely, the SADI-sleeve, the transit bipartition and the endosleeve.

These procedures are not without short and long-term complications. In fact, clinical and biological follow-ups are essential.

WHO TO OPERATE ON?

Indicators that bariatric surgery may be appropriate in adults (HAS 2009 recommendations) are as follows:

• Body mass index (BMI) ≥ 40 kg/m2, or BMI ≥ 35 kg/m2 with a comorbidity likely to be improved by surgery, such as arterial hypertension or other cardiovascular disease, sleep apnoea syndrome and other ventilatory disorders, type 2 diabetes and other metabolic disorders, disabling osteoarticular disease, and non-alcoholic fatty liver disease;
• As a second-line treatment, after failure of a 6-12 months’ medical treatment with good follow-up;
• In the absence of sufficient weight loss or maintenance of weight loss;
• A patient who has been well informed beforehand, has benefited from a multidisciplinary evaluation and management, and has accepted the need for long-term medical and surgical follow-up,
• An acceptable operative risk.

Contraindications to bariatric surgery are severe cognitive or mental disorders, severe or unstabilised eating disorders, inability to undergo prolonged medical follow-up, addictions, lack of prior medical care, short-term or medium-term life-threatening illness, pregnancy, or contraindication to general anaesthesia.

Non-indications are a BMI between 30 and 35 kg/m2, an age > 60 years (to be discussed on a case-by-case basis) and genetic or lesion-based obesity.

The decision should be coordinated by a referral doctor and taken during a multidisciplinary consultation meeting. It will be validated by the doctor of the Caisse Primaire d’Assurance Maladie, within the framework of a pre-surgery agreement.

Surgery is not a cure for obesity in itself; it involves replacing a chronic metabolic disease, with its specific morbidity and mortality, with a lasting modification to the digestive system. Lifelong follow ups are necessary.

PRE-OPERATIVE COURSE OF THE PATIENT

EXPECTED BENEFITS AND COMPLICATIONS

Expected benefits
There are many reasons for choosing bariatric surgery: effective and permanent weight loss, improvement in quality of life with better vital energy and increased self-confidence, reduction in comorbidities and increased fertility.

The literature is rich to show that, whatever the technique, a loss of excess weight is always expected postoperatively.

As far as comorbidities are concerned, weight loss and surgery are effective at reducing these.

Regardless of the initial BMI, fasting blood sugar levels drop quite early and type 2 diabetes regresses or even disappears.

Cardiovascular risk is also reduced, especially hypertension and dyslipidaemia.

Steatohepatitis (NASH) also improves.

Rather than obesity surgery, we can therefore speak of metabolic surgery.

Overall, the long-term mortality risk to the patient decreasing.

Complications
Digestive complications
Some digestive complications can be avoided or minimised by explaining the dietary rules to the patient. Others are inherent to the surgical set-up: vomiting, transit disorders, dysphagia, oesophagitis, and dumping syndrome (malaise after eating, see below), particularly after gastric bypass.

Psychological and social complications
These are rare, given the general improvement in the quality of life offered by bariatric surgery. However, some patients may decompensate for an old addiction, or develop eating disorders or dysmorphophobia. Weight loss can also sometimes exacerbate an already tense family or professional situation. The surgical procedure does not guarantee happiness in all areas.

Surgical complications
There are several key specificities associated with the various techniques:

• Ring: Turning of the case preventing adjustments, maladjustment of the catheter, slipping of the ring or stipping;
• Sleeve and bypass: Fistula, stenosis, haemorrhages, embolisms, occlusion, anastomotic ulcer;
• Bypass: Peterson’s internal hernia, bile reflux in the case of omega assembly in particular.

Qualified centres with biology, radiology, surgery, interventional endoscopy and surgical resuscitation facilities are responsible for managing these complications.

Functional medical complications
There are two main types: dumping syndrome (after malabsorptive surgery, such as gastric bypass) and hypoglycaemia.

The symptoms of dumping syndrome are post-prandial and appear early. The intake of rich, sweet and/or fatty hyperosmotic foods leads to extracellular dehydration, and typically the patient will ask to lie down because they experience vasomotor symptoms (headache, palpitations, flush, pallor, syncope) and abdominal symptoms (nausea, abdominal cramps, diarrhoea, borborygma).

Late hypoglycaemia (1-3 hours after the meal) occurs in 10-15% of patients operated on (very severe hypoglycaemia in 1-2% of cases). Patients present with hunger, confusion, difficulty concentrating, and sweating.

If the patient follows the dietary recommendations properly, these complications are extremely rare. It should be explained to the patient that if these symptoms occur, they should lie down (and park if driving). In general, before mentioning a surgical complication, it should be kept in mind that the basic hypoglycaemic treatments must be readjusted very regularly; splitting meals and eating foods with a low glycaemic index is recommended (see 6.1.3).

Nutritional complications
Micronutrient absorption is impaired after bypass surgery, mainly due to short-circuiting of the duodenum, the main site of micronutrient absorption, achlorhydria and decreased intrinsic factor.

Although sleeve surgery does not alter intestinal continuity, it also results in micronutrient deficiencies, due to the decrease in intrinsic factor and hydrochloric acid, secondary to the removal of a large portion of the stomach. The very rapid passage of the food bolus through the duodenum prevents proper absorption of micronutrients.

Screening and treatment of pre-operative deficiencies is important to minimise post-operative deficiencies (6).

During the weight loss phase, oral intake is often insufficient and the patient needs to be supplemented (7).

CLINICOBIOLOGICAL MONITORING OF PATIENTS BEFORE AND AFTER BARIATRIC SURGERY

Basic principles
The follow-up will always be multidisciplinary, involving the attending physician, surgeon, nutritionist, psychologist and APA educator.
The doctor must detect surgical and digestive complications and check:

• Patient’s dietary and digestive comfort;
• Timing of food intake;
• Biometry and impedance measurement;
• Screening for deficiencies; and, in particular
• Improvement of co-morbidities.

They should also re-evaluate the dosage of treatments for co-morbidities, or even stop them, and check the settings of the sleep apnoea machine (CPAP).

Over time, it is necessary to monitor a possible weight regain, the appearance of functional complications, and the resurgence of bad eating habits.

In the context of malabsorptive surgery, it is essential to check compliance with vitamin therapy and to pay attention to signs of deficiency, in order to complete the supplementation if necessary:

• Severe vomiting, digestive disorders: vitamin B1 ++,
• Infections: proteins, vitamin D,
• Dry skin, dermatitis, ecchymosis, petechiae, alopecia: zinc, iron, proteins, vitamin C,
• Paresthesias, neurological and psychiatric disorders: group B vitamins, zinc, copper,
• Vision anomalies: vitamin A,
• Bleeding: vitamin K.

The follow-up will also be psycho-motivational and seek to detect the appearance of eating disorders, addiction (new or resurgent) and dysmorphophobia, as well as evaluating the quality of life, personal/intimate fulfilment, and socio-professional fulfilment, etc.

The APA educator will help the patient to increase their level of physical activity with realistic and achievable objectives.

Finally, away from the surgery and once weight loss has stabilised, skin prognosis and the possibility of reconstructive surgery will be discussed.

Basic rules of daily nutrition

• Small meals: 3 meals + 2 snacks for life.
• Eat proteins (meat or vegetable) at every meal.
• Start the meal with proteins.
• Encourage protein intake with each snack.
• Never drink while eating and respect the time interval before and after eating.
• Never drink fizzy drinks.
• Take time to eat, chew well, put the cutlery down between each mouthful.
• Before each bite, ask yourself if you are still hungry.
• Avoid eating too much fat, salt or sugar.
• Allow yourself occasional pleasurable meals, without feeling guilty.

Dietary instructions for the first month of surgery

• D1 to D15: “baby jar” consistency without pieces
• Days 15 to 30: “baby food” consistency with pieces
• Exercise at least 3 times a week (walking, gym, cycling, dancing…), move around for at least 30 minutes per day.

Beware of dumping syndrome, which occurs as a result of rapid ingestion of sugary and fatty products. The most common symptoms are hot flushes, sweating, palpitations, paleness, tachycardia, abdominal pain, diarrhoea, and nausea. If these symptoms appear, lie down and hydrate.

If you vomit, you may have:

• Eaten too quickly
• Eaten too much
• Eaten large pieces
• Drunk while eating

PRE- AND POST-OPERATIVE BIOLOGICAL MONITORING

Screening for pre-operative and post-operative deficiencies

Before the operation, the diet of the obese patient is generally richer in fats and sugary products, and therefore with a high energy density and low nutritional density. This type of diet is associated with a low content of vitamins, proteins, minerals and fibres. Increased energy intake increases the need for micronutrients, which increases the risk of deficiency. Obese patients are therefore likely to have specific deficits or deficiencies. The most common deficiencies are in vitamins B1, B12, B9, A, C, D and E. However, vitamin or micronutrient status based on serum markers alone is questionable in the obese patient, due to the storage of some vitamins in adipose tissue and a different volume of distribution.

In practice, screening for major deficiencies is recommended pre-operatively and during follow-up. The correction of deficiencies before the operation is very important to limit postoperative nutritional complications. It is particularly important to correct protein malnutrition before the operation, to promote healing.

A prescription for multivitamins post-operatively is systematic during the weight loss phase, but is often insufficient (3).

Proteins

Protein deficiencies are frequent in the pre-operative period (obese people are sarcopenic) and the first six months post-operatively, particularly if weight loss is very rapid and/or in the event of vomiting or intercurrent illness. Several mechanisms can be incriminated: lack of intake due to food restriction and a certain distaste for meat, reduction in secretions (pancreatic, pepsinogen, etc.), reduction in intestinal absorption surface (exclusion of the duodenum).

These deficiencies manifest as muscle loss, asthenia and skin disorders. Monitoring is based on albumin, prealbumin and CRP measurements (interpretation of albumin levels according to the inflammatory state).

The recommended nutritional intake includes at least 60g of protein per day, which is often impossible in the postoperative period, hence the use of high-protein supplements, if necessary, in liquid or powder form (3). This is in conjunction with 30 minutes of walking per day, to limit the loss of muscle mass.

Iron

Deficiencies are frequent in the pre-operative period, affecting 0 to 47% of patients, depending on the series (8). Post-operatively, patients must be systematically supplemented (3).

Post-sleeve iron deficiency can be explained by the lack of gastric acid secretion, secondary to resection and long-term use of proton pump inhibitors (9).

The main signs of deficiency are asthenia, pallor and anaemia. Screening is based primarily on serum ferritin measurement.

Oral supplementation (100 mg/d) or IV supplementation is recommended if ferritin is < 30 mg/L or haemoglobin < 10 g/dL (300 mg IV at D1 and D3). Iron absorption can be improved by the co-administration of vitamin C.

However, long-term oral iron intake is not without its drawbacks, as it can lead to digestive problems, as well as problems with the absorption of manganese, chromium and selenium (3).

Folate (folic acid, vitamin B9)

Preoperative deficiencies are common (0-63%) (8).

Folic acid is absorbed throughout the gastrointestinal tract but requires pancreatic juices – there are absorption problems after bypass surgery. However, routine supplementation is not necessary; multivitamins are usually sufficient.

The signs of deficiency are macrocytosis, hyperhomocysteinemia, asthenia and anaemia. In pregnant women, there is a risk of neural tube defect in the foetus, hence the recommendation to supplement women of childbearing age at least 12 weeks before conception, to be continued 12 weeks afterwards, at a minimum dose of 5 mg/d (3, 10).

Vitamin B12 (cyanocobalamin)

Preoperative deficiencies are relatively common (0-23%) (8).

Vitamin B12 (cyanocobalamin) is a cofactor in the synthesis of succinyl coA and methionine, which are involved in nerve cell function. There is a hepatic reserve for vitamin B12 and the stock of vitamin B12 is usually sufficient for 6-12 months.

Post-operatively, vitamin B12 deficiency occurs due to the resection of the fundus and the lack of intrinsic factor normally produced by the parietal cells. Vitamin B12, like folic acid, requires gastric acid to be extracted from food (9).

Vitamin B12 deficiency is manifested by macrocytic anaemia, dysgeusia, glossitis and neurological disorders, which can be severe (neuropathy, early cognitive decline) (3, 10).

After a bypass, it is recommended to administer a daily oral dose, but the simplest is a 1000g/month IM ampoule for life (3). In the event of microbial proliferation, administration should be by IV.

After a sleeve, there is no general consensus regarding supplementation. This will be done according to the results of the dosages (3). There is no toxicity associated with overdose.

In view of the reservations, there is little point in an early dosage of vitamin B12.

Vitamin D and calcium

Obese people are more often deficient in vitamin D (up to 90%) than the general population, due to the sequestration of vitamin D in fat and their reduced exposure to sunlight, sedentary lifestyle, and propensity to wear well-covered clothing.

Post-operative deficiencies can be explained by several mechanisms: lactose is poorly tolerated, calcium needs gastric acid to be absorbed, absorption is mainly in the proximal small intestine, post-bypass steatorrhoea leads to a loss of fat-soluble vitamins including vitamin D, and the decrease in leptin affects bone metabolism.

These combined deficits result in an increase in parathyroid hormone (PTH), the first detectable abnormality, whereas corrected calcaemia very often remains normal (10). Thus, hyperparathyroidism is found postoperatively in 40% of patients, with an increased risk of osteoporosis and even osteomalacia (11).

The recommendation is to supplement as soon as the PTH increases, with one 100,000 IU ampoule of vitamin D per month, alongside with 1g of calcium, taken twice a day – calcium citrate is preferred due to its better bioavailability. It is also important to monitor surgically induced osteoporosis by regular post-bypass bone densitometry (3, 10).

Vitamin B1 (thiamine)

Vitamin B1 is a water-soluble vitamin involved in nerve transmission and is a cofactor in many glucose metabolism enzymes. Its stock in the body is low and can collapse in 3-6 weeks. A major risk factor is the consumption of alcohol, the absorption of which competes with that of the proximal jejunum, therefore its consumption must be totally banned at least for the first six months following bariatric surgery. Post-operative deficiencies are very frequent, i.e. up to 49% in the literature (12). Complications related to deficiencies occur early, after any type of surgery:

• Gayet-Wernicke encephalopathy (acute): confusion, oculomotor disorders (nystagmus or oculomotor paralysis), cerebellar syndrome;
• Korsakoff’s encephalopathy (chronic): anterograde amnesia, anosognosia, false recognitions and fabrications;
• Peripheral neuropathy: neurological “beri beri” (sensitive, motor, painful, distal, symmetrical polyneuropathy).

Decreased serum vitamin B1/thiamine concentration is not constant; sometimes the deficiency can be demonstrated by a decrease in erythrocyte thiamine and/or erythrocyte transketola activity.

Substitution of 100 mg/d orally is usually sufficient (3). In cases of suspected Gayet Wernicke encephalopathy, a dose of 500 mg by IV, three times a day for three days, is recommended, combined with magnesium (enzyme cofactor), then 250 mg a day for five days.

In cases of vomiting, it is recommended to supplement with vitamin B1 by 100 mg/d administered by IV immediately (never combine with glucosed serum), whatever the result of any assays. There is no toxicity in hypervitaminosis B1.

Zinc

Zinc deficiency occurs in almost one in two patients one year after bypass and in one in four patients after sleeve. It may manifest itself as anorexia, hyposmia/agueusia, hair loss or eczema, or in more severe forms, by mental disorders or severe skin lesions. Oral substitution with 15 to 30 mg/d of zinc is indicated if there is a deficiency, but care should be taken to avoid interference with absorption when iron is taken at the same time. It is not advisable to take zinc at a similar time to other supplements; however, 1 mg of copper should always be combined with 10 mg of zinc (see below).

AEK Vitamine

Deficiencies of these fat-soluble vitamins are quite rare.

• Vitamin A deficiency leads to visual disturbances, reduced male fertility and foetal abnormalities (measure beta HCG before giving vitamin A). Recommendations are 50,000 IU/week (3).
• Vitamin E deficiency can cause peripheral neuropathy, muscle weakness, and ataxia. Supplement with 400 IU/d (3).
• Vitamin K deficiency can cause coagulation disorders. Supplement with 2 mg/week.

However, these deficiencies are rare; vitamin K tests may only be performed once a year after malabsorptive surgery.

Copper

Multivitamin supplements generally contain enough copper to prevent deficiency, which is rare after bariatric surgery, but it should be considered in the presence of anaemia that does not respond to iron supplementation, particularly in patients on zinc replacement (the absorption of which interferes with that of copper). This deficiency can also appear as visual or neurological disorders. If symptoms are present, oral supplementation with 3 to 5 mg/d of copper is indicated (3).

Biological monitoring rhythm

Suggestions for systematic pre- and post-operative check-ups

•  Pre-operatively: albumin, haemoglobin (CBC), ferritin and transferrin saturation coefficient (TC), blood calcium, 25OH-vitamin D, vitamins B1, B9, B12 (HAS recommendations).

This assessment can be completed by fasting glycaemia, HbA1c, C-peptide, exploration of a lipid anomaly (EAL), blood ionogram, vitamin A, erythrocyte vitamin B9, magnesium, phosphates, TSH, albumin and pre-albumin, hepatic assessment, CRPus.

• Post-operatively (according to 3, 13), the following monitoring scheme can be proposed:

If unexplained anaemia, look for copper deficiency.
If hair loss: measure ferritin, proteins, zinc, B vitamins.
Assessment to be completed, depending on comorbidities, clinical situations, etc.: HBA1c, complete martial assessment, selenium, vitamin C, etc

CONCLUSION

All patients who have undergone bariatric surgery must be followed up in the long term. The multidisciplinary management process places the patient at the centre, as the main actor in their care, as well as the attending physician, who is a strong link in the chain of care, together with the surgeon, nutritionist, dietician, psychologist and APA educator.

It is important to detect and treat any vitamin or trace element deficiency before and after the operation. This monitoring is essential to prevent complications and adapt management. The treatment of co-morbidities will also have to be readjusted. In all cases, physical activity must be encouraged, or even systematised.

BIBLIOGRAPHIE

1. Busetto L, Dicker D, Azran C, et al. Practical Recommendations of the Obesity Management Task Force of the European Association for the Study of Obesity for the Post-Bariatric Surgery Medical Management. Obes Facts. 2018 Feb; 10(6): 597–632.
2. HAS. Obésité : prise en charge chirurgicale chez l’adulte. Janvier 2009.
3. Quillot D, et al. Recommendations for nutritional care after bariatric surgery: Recommendations for best practice and SOFFCO-MM/AFERO/SFNCM/expert consensus. Journal of Visceral Surgery 2020 ;158 : 51-61.
4. Tarrerias AL. Suivi après chirurgie bariatrique. Ateliers POST’U 2015.
5. HAS Synthèse. Nouvelles techniques de chirurgie bariatrique : identification, état d’avancement et opportunité d’évaluer. Validée par le Collège le 10 septembre 2020.
6. Parrott J, Frank L, Rabena R, Craggs-Dino L, Isom KA, Greiman L. American Society for Metabolic and Bariatric Surgery integrated health nutritional guidelines for the surgical weight loss patient 2016 update: micronutrients. Surg Obes Relat Dis. 2017(13):727-741.
7. Kanerva N, Larsson I, Peltonen M, Lindroos A.-K,  Carlsson L.M. Changes in total energy intake and macronutrient composition after bariatric surgery predict long-term weight outcome: findings from the Swedish Obese Subjects (SOS) study. Am J Clin Nutr, 106 (2017), pp. 136-145, 10.3945/ajcn.116.149112
8. O’Kanel M, Paretti HM, Pinkney J, et al, British Obesity and Metabolic Surgery Society Guidelines on perioperative and postoperative biochemical monitoring and micronutrient replacement for patients undergoing bariatric surgery—2020 update.
9. Gillon, S.; Jeanes, Y.M.; Andersen, J.R.; Våge, V. Micronutrient Status in Morbidly Obese Patients Prior to Laparoscopic Sleeve Gastrectomy and Micronutrient Changes 5 years Post-surgery. Obes. Surg. 2016, 27, 606–612.)
10. Favre L, Ferrario C, Mantziari S, Suter M. Recommandations de suivi des carences nutritionnelles après chirurgie bariatrique. Rev Med Suisse 2019; 15 : 626-30.
11. Damms-Machado, A.; Friedrich, A.; Kramer, K.M.; Stingel, K.; Meile, T.; Küper, M.A.; Königsrainer, A.; Bischoff, S.C. Pre- and Postoperative Nutritional Deficiencies in Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy. Obes. Surg. 2012; 22:881–889.
12. Tang L, Alsulaim HA,  Canner J.K, Prokopowicz GP, Steele KE. Prevalence and predictors of postoperative thiamine deficiency after vertical sleeve gastrectomy. Surg Obes Relat Dis, 14 (2018), pp. 943-950, 10.1016/j.soard.2018.03.024).
13. Quillot D. Prévention et traitement des carences en vitamines, minéraux et oligoéléments après chirurgie de l’obésité. La lettre de l’hépato-gastroentérologue 2010 ;XIII :4-5.

ANNEXES

RECOMMANDATIONS HAS 2009
https://www.has-sante.fr/upload/docs/application/pdf/2011-12/recommandation_obesite_-_prise_en_charge_chirurgicale_chez_ladulte.pdf

BROCHURE HAS DU PATIENT
https://www.has-sante.fr/upload/docs/application/pdf/2009-09/brochure_obesite_patient_220909.pdf

ARTICLE DE LA SOFFCO
https://pubmed.ncbi.nlm.nih.gov/33436155/

STANDARD POSTOPERATIVE PRESCRIPTION

1. a proton pump inhibitor
2. a “bile thinner” such as ursodeoxycholic acid
3. vitamins : the most important thing is to take a daily multivitamin of your choice.