Heartbreaking weight loss

Review article: The nutritional and pharmacological consequences of obesity surgery

BACKGROUND

Obesity surgery is acknowledged as a highly effective therapy for morbidly obese patients. Beneficial short-term effects on common comorbidities are practically undisputed, but a growing data pool from long-term follow-up reveals increasing evidence of potentially severe nutritional and pharmacological consequences.

AIMS

To assess the prevalence, causes and symptoms of complications after obesity surgery, to elucidate and compare therapy recommendations for macro- and micronutrient deficiencies, and to explore surgically-induced effects on drug absorption and bioavailability, discussing ramifications for long-term therapy and prophylaxis.

METHODS

PubMed, Embase and MEDLINE were searched using terms including, but not limited to, bariatric surgery, gastric bypass, obesity surgery and Roux-en-Y, coupled with secondary search terms, e.g. anaemia, micronutrients, vitamin deficiency, bacterial overgrowth, drug absorption, pharmacokinetics, undernutrition. All studies in English, French or German published January 1980 through March 2014 were included.

RESULTS

Macro- and micronutrient deficiencies are common after obesity surgery. The most critical, depending on surgical technique, are hypoalbuminemia (3-18%) and deficiencies of vitamins B1 (≤49%), B12 (19-35%) and D (25-73%), iron (17-45%) and zinc (12-91%). Many drugs commonly administered to obese patients (e.g. anti-depressants, anti-microbials, metformin) are subject to post-operative and/or PPI-associated changes affecting bioavailability and absorption.

CONCLUSIONS

Complications are associated with pre-operative and/or post-operative malnutrition or procedure-related changes in intake, absorption and drug bioavailability. The high prevalence of nutrient deficiencies after obesity surgery makes life-long nutritional monitoring and supplementation essential. Post-operative changes to drug absorption and bioavailability in bariatric patients cast doubt on the validity of standard drug dosage and administration recommendations.

Managing medical and surgical disorders after divided Roux-en-Y gastric bypass surgery

The National Longitudinal Study of Adolescent Health and the National Health and Nutrition Examination Survey reported that over 40% of the US population is overweight. The average weight loss attained by medical management programs is neither sufficient nor durable enough to treat medically complicated obesity. An estimated 220,000 bariatric procedures are performed yearly in the USA and Canada. The divided Roux-en-Y gastric bypass (RYGB) is performed most commonly in these countries and is considered the gold standard bariatric surgical procedure. The complexity of RYGB means that serious and potentially preventable perioperative complications can occur. RYGB alters the normal anatomy and physiology of the upper gut, which has predictable adverse effects and potential complications. Patients seek advice and care for symptoms that develop or persist after RYGB; although some symptoms are expected and predictable, others are complications that may or may not require active medical or surgical intervention. Physicians should be able to predict and manage most postoperative medical and nutritional disorders related to RYGB and should be prepared to assess patients for potential referral for surgical intervention or revision.