Low-Purine Diet Is More Effective Than Normal-Purine Diet in Reducing the Risk of Gouty Attacks After Sleeve Gastrectomy in Patients Suffering of Gout Before Surgery: a Retrospective Study

Bariatric Surgery and Its Metabolic Echo Effect on Serum Uric Acid Levels

Bariatric surgery (BS) has been a significant means of reducing weight in obese individuals. The metabolic changes after bariatric surgery are crucial as they extend its advantages beyond weight loss. As its name implies, "metabolic surgery" also addresses obesity-related metabolic concerns. Bariatric surgery has always been associated with lessened serum uric acid (SUA) levels. In this review, we examined current studies to understand how surgical therapies impact serum uric acid levels. Strongly minded on the extent and timing of changes in the level of serum uric acid after bariatric surgeries. We conducted a comprehensive search for relevant current studies in PubMed, Google Scholar, JAMA, and the Cochrane Library until February 1, 2024. We aimed to analyze the metabolic advantages of bariatric surgery, focusing on its function in treating hyperuricemia and lowering the risk of associated disorders. Our review elaborates on factors contributing to decreased serum uric acid levels after bariatric surgery, such as alterations in renal function, insulin sensitivity, and inflammatory markers.

Efficient removal of purine compounds from solutions via biomass carbons derived from pomelo peel

The high purine diet could result in the increase of the level of blood uric acid, causing serious health problems such as hyperuricemia, gout, nephropathy and cardiovascular diseases. To find out a safe, cheap and super adsorption material for removing purines in stomach or pretreating high-purine beverages, we used different tissues of pomelo peel to prepare biomass carbon by drying, chemical modification and carbonization and then applied it to remove purine compounds in strong acidic solution, beer and soybean milk. The characteristic analysis of pomelo-peel-derived carbons (PPCs) indicated that the preparation methods significantly affected the structures and adsorption capacities of PPCs. Compared with the biomass carbon derived from bamboo, PPCs exhibited higher adsorption capabilities for purine compounds in strong acidic solution (adsorption rates > 99% in 15 min) and soybean milk (adsorption rates > 56% in 30 min) but slightly lower adsorption capabilities in beer (adsorption rates > 52% in 30 min). In addition, the adsorption capabilities of PPCs for purine compounds in beer and soybean milk were not obviously affected by temperatures. Therefore, PPCs are promising absorbents for applications in removing purine compounds from beverages to produce low-purine, healthier products for treating hyperuricemia. The strong adsorption capabilities of PPCs on purine compounds in strong acidic environment also provides a possibility of using the PPCs as food additives for removing purines in stomach for healthcare applications such as gout prevention after confirming their biosafety.

Long-term impact of sleeve gastrectomy on serum uric acid levels

BACKGROUND

Obesity is a risk factor for hyperuricemia. Bariatric surgery is an effective treatment method for metabolic control. The aim of our study was to evaluate the correlation between the preoperative and postoperative serum uric acid levels with body mass index, body weight, and excess weight loss in patients that underwent sleeve gastrectomy.

METHODS

A total of 164 patients that underwent laparoscopic and open sleeve gastrectomy were evaluated in terms of the demographic characteristics, preoperative body weight, body mass index and serum uric acid levels, and postoperative body weight, body mass index, excess weight loss and serum uric acid levels at the first, third, sixth, 12th, 18th and 24th-36th months.

RESULTS

There was a statistically significant increase in serum uric acid levels in the first postoperative month (p = 0.000). The patients with a high preoperative body mass index were found to have a lower excess weight loss in the first postoperative month, which was statistically significant (p = 0.000, R = -0.474). Serum uric acid levels were also positively correlated with body weight at the third and sixth postoperative months.

DISCUSSION

The weight loss associated with sleeve gastrectomy is the main reason for the reduced postoperative serum uric acid levels.

Gouty arthritis and kidney function outcomes and serum uric acid level variations in obese patients following bariatric surgery

Background

Obesity is an independent risk factor for chronic kidney disease (CKD) and is the strongest known modifiable risk factor for hyperuricemia and gout. We aimed to discover the outcome of serum uric acid (SUA), gouty arthritis, and kidney function in obese patients after bariatric surgery and possible links with BMI variations.

Methods

Retrospective study has been performed in National Hospital in Riyadh, KSA, between Jan. 2018 to Jan. 2020. We studied only 98 patients who met our inclusion criteria. Patients followed-up at 1 month (for gouty attack only) postoperative, 3 months postoperative, and 6 months postoperative for body mass index (BMI), serum creatinine, dipstick urinalysis, SUA, and estimated glomerular filtration rate (eGFR). Radiological studies, medical history, follow up radiological studies, and clinical follow up were obtained from the hospital data system.

Results

A total of 98 patients with mean eGFR were 90.65 ± 29.34 ml/min/1.73 m2, mean SUA 5.56 ± 1.84 mg/dl, and mean BMI was 45.28 ± 7.25 kg/m2, at surgery. Mean BMI had decreased significantly to 38.52 ± 6.05 kg/m2 at 3 months and to 34.61 ± 5.35 kg/m2 at 6 months (P < 0.001). The mean GFR had improved significantly (99.14 ± 23.32 ml/min/1.73 m2) at 6 months (P < 0.001). Interestingly, proteinuria had resolved in 17 patients out of 23 patients at 6 months. Number of gouty attacks was decreased during the first month post-surgery (P < 0.001). SUA level was significantly decreased (4.32 ± 1.27 mg/dl) (P < 0.001). SUA showed significant negative correlations with eGFR at 3 months and positively significant correlations with BMI at 3 and 6 months. By multinomial logistic regression, BMI and initial eGFR were the independent predictive variables for the outcome of eGFR at 6 months, while male gender and initial SUA were the independent predictive variables on the outcome of SUA at 6 months. Postoperatively in gouty arthritis patients, the number of joints affected, patient global VAS assessment, and number of gouty attacks were significantly reduced (P < 0.001).

Conclusion

Bariatric surgery has been associated with reduction of BMI and subsequently reduction of SUA levels, gouty attacks, and improvement of eGFR.

Role of diet in hyperuricemia and gout

BACKGROUND

Gout is the most common form of inflammatory arthritis, affecting 41 million adults worldwide. The global burden of gout has been increasing over the last three decades, yet its management remains suboptimal. The primary aim of this manuscript is to review the impact of various diets such as the DASH, Mediterranean, and low purine diets; weight loss; and individual foods, including alcohol, caffeine, cherry, dairy, high-fructose corn syrup, omega-3 fatty acids, and vitamin C on hyperuricemia and clinical gout outcomes such as flares and tophi.

CONCLUSION

Few studies to date have specifically evaluated the effect of various dietary approaches on hyperuricemia among people with gout and on gout-specific outcomes. Overall, the dietary factors appear to have a small effect on serum urate levels, and their impact on the long-term clinical course of gout is uncertain. Limited evidence suggests that avoidance of certain foods and beverages may decrease the frequency of gout flares. Weight loss may be beneficial for prevention as well as treatment of gout. Urate-lowering therapy remains the mainstay of therapy, with diet and dietary factors studied to date playing a limited role in the definitive management of gout.

Low-Calorie Ketogenic Diet with Continuous Positive Airway Pressure to Alleviate Severe Obstructive Sleep Apnea Syndrome in Patients with Obesity Scheduled for Bariatric/Metabolic Surgery: a Pilot, Prospective, Randomized Multicenter Comparative Study

Obstructive sleep apnea syndrome (OSAS) and obesity are frequently associated with hypertension (HTN), dyslipidemia (DLP), and insulin resistance (IR). In patients with obesity and OSAS scheduled for bariatric surgery (BS), guidelines recommend at least 4 weeks of preoperative continuous positive airway pressure (CPAP). Low-calorie ketogenic diets (LCKDs) promote pre-BS weight loss (WL) and improve HTN, DLP, and IR. However, it is unclear whether pre-BS LCKD with CPAP improves OSAS more than CPAP alone. We assessed the clinical advantage of pre-BS CPAP and LCKD in patients with obesity and OSAS. Seventy patients with obesity and OSAS were randomly assigned to CPAP or CPAP+LCKD groups for 4 weeks. The effect of each intervention on the apnea–hypopnea index (AHI) was the primary endpoint. WL, C-reactive protein (CRP) levels, HTN, DLP, and IR were secondary endpoints. AHI scores improved significantly in both groups (CPAP, p=0.0231; CPAP+LCKD, p=0.0272). However, combining CPAP and LCKD registered no advantage on the AHI score (p=0.863). Furthermore, body weight, CRP levels, and systolic/diastolic blood pressure were significantly reduced in the CPAP+LCKD group after 4 weeks (p=0.0052, p=0.0161, p=0.0008, and p=0.0007 vs baseline, respectively), and CPAP+LCKD had a greater impact on CRP levels than CPAP alone (p=0.0329). The CPAP+LCKD group also registered a significant reduction in serum cholesterol, LDL, and triglyceride levels (p=0.0183, p=0.0198, and p<0.001, respectively). Combined with CPAP, LCKD-induced WL seems to not have a significant incremental effect on AHI, HTN, DLP, and IR but lower CRP levels demonstrated a positive impact on chronic inflammatory status.

Long-Term Results of the Mediterranean Diet After Sleeve Gastrectomy

BACKGROUND

To assess dietary habits in a cohort of patients at minimum follow-up of 4 years after sleeve gastrectomy (SG) by comparing their dietary records to the Italian Mediterranean diet (IMD) recommendations.

METHODS

We prospectively evaluated in 74 patients who had the SG in 2014 dietary habits by a 7-day food dietary records, weight and micronutrient status, evolution of comorbidities, use of micronutrient supplements, and frequency of physical activity.

RESULTS

The IMD recommendations in terms of daily/weekly portions of fruits, vegetables, and complex carbohydrates were followed by 40.5%, 35.1%, and 40.5% of the participants, respectively. Concerning milk/dairy, olive oil, poultry, fish/shellfish, eggs, legumes, processed/red meat, and cold cuts, 54.1%, 85.1%, 44.5%, 75.7%, 67.6%, 35.1%, 87.8%, and 55.4% of the participants, respectively, followed the IMD recommendations. Weight regain appeared in 37.8% of participants, while physical activity was reported by the 54.0% of them. Deficiencies of vitamin B12, vitamin D, folate, iron, and anemia were found present in 6.8%, 8.1%, 24.3%, 33.8%, and 59.5% of the participants, respectively, and 18.9% of them were found to take micronutrient supplements. Improvement/remission of type 2 diabetes, hypertension, or obstructive sleep apnea was 73.3%, 64.7%, and 100% respectively.

CONCLUSIONS

In this prospective cohort with a minimum follow-up of 4 years after SG, we found an inadequate intake of fruit, vegetables, poultry, and complex carbohydrates according to the IMD recommendations; the frequency of physical activity and the use of micronutrients supplements were also inadequate. This may contribute to weight regain and micronutrient deficiencies in the long term.

Impact of bariatric surgery on serum uric acid levels and the incidence of gout-A meta-analysis

Gout is characterized by high serum uric acid (SUA) levels and arthritis. It is associated with obesity and metabolic syndrome. Bariatric surgery has been associated with decreased SUA levels and overall gout incidence. This meta-analysis aims to summarize the current evidence on bariatric surgery, gout and SUA levels. A literature review was performed on papers published from 2000 up till December 2018. Original studies investigating the impact of bariatric surgery on SUA levels or gout incidence were evaluated. Twenty studies with a total of 5,233 patients were analysed. Majority (n=14) had a follow-up duration of at least 12 months. The mean preoperative body mass index (BMI) was 45.2kg m^-2 . The mean preoperative SUA level was 6.5mg dL^-1 . Subgroup analysis demonstrated a mean decrease in SUA levels (-0.73mg dL^-1 ) from the third postoperative month onwards, which was sustained until the third postoperative year (-1.91mg dL^-1 ). There was a rise in SUA levels in the first post-operative month. Meta-regression analyses demonstrated a proportionate linear relationship between the change in BMI and SUA levels. Post-bariatric surgery weight loss is associated with reduced SUA levels and decreased incidence of gout attacks. However, this is only evident from the third post-operative month onwards.

A 4-Week Preoperative Ketogenic Micronutrient-Enriched Diet Is Effective in Reducing Body Weight, Left Hepatic Lobe Volume, and Micronutrient Deficiencies in Patients Undergoing Bariatric Surgery: a Prospective Pilot Study

BACKGROUND

Before bariatric surgery (BS), moderate weight loss, left hepatic lobe volume reduction, and micronutrient deficiency (MD) identification and correction are desirable.

OBJECTIVES

The objective of this study was to assess the safety and the effectiveness of a 4-week preoperative ketogenic micronutrient-enriched diet (KMED) in reducing body weight (BW), left hepatic lobe volume, and correcting MD in patients scheduled for BS.

MATERIALS AND METHODS

In this prospective pilot study, a cohort of morbidly obese patients (n = 27, 17 females, 10 males) with a mean body mass index (BMI) of 45.2 kg/m² scheduled for BS underwent a 4-week preoperative KMED. Their BW, BMI, fat mass (FM), fat-free mass (FFM), resting metabolic rate (RMR), left hepatic lobe volume, micronutrient status, and biochemical and metabolic patterns were measured before and after the 4-week KMED. Patient compliance was assessed by validated questionnaires (3-day estimated food records and 72-h recall). Qualitative methods (5-point Likert questionnaire) were used to measure diet acceptability and side effects.

RESULTS

All patients completed the study. We observed highly significant decreases in BW (- 10.3%, p < 0.001, in males; - 8.2%, p < 0.001, in females), left hepatic lobe volume (- 19.8%, p < 0.001), and an amelioration of patient micronutrient status. All patients showed a high frequency of acceptability and compliance in following the diet. No adverse side effect was reported.

CONCLUSION

This study demonstrates that a 4-week preoperative KMED is safe and effective in reducing BW, left hepatic lobe volume, and correcting MD in obese patients scheduled for BS.

Postoperative Recurrent Gout Flares: A Cross-sectional Study From China

OBJECTIVES

To investigate the morbidity, clinical characteristics, and risk factors for postoperative recurrent gout flares (PRGFs).

METHODS

This cross-sectional study included all surgical patients at 2 academic institutions between 2010 and 2018. Data including demographics, prior history of gout, clinical variables, medications, and the occurrence of PRGFs were abstracted from medical records. Forward stepwise multivariable logistic regression analysis was used in the statistical analyses.

RESULTS

Among the 518 (0.5% [518/114,760]) surgical patients with a prior diagnosis of gout, 474 had sufficient documentation for analysis. Of these, 191 (40.3%) had experienced a PRGF. Most PRGFs (54.4%) were polyarticular gout; 79.6% had a pretreatment pain score of PRGFs ≥7, and 59.2% required combination pharmacologic therapy. The mean (SD) serum urate (SU) level decreased postoperatively (500.33 [122.77] vs. 380.15 [118.35] μmol/L; p = 0.000), with an average decrease of 125.86 μmol/L. The decrease in the postsurgical SU level was greater in patients who received postoperative total parenteral nutrition (PTPN) than in those who did not (p = 0.009), and it was correlated with the duration of PTPN (r = 0.156, p = 0.031). Factors independently associated with PRGFs were decrease in the postsurgical SU level by ≥126 μmol/L, previous flares involving the ankle, failure to take prophylactic colchicine therapy, and abdominal surgery.

CONCLUSIONS

Recurrent gout flares often occur postoperatively and are severe. For high-risk patients, especially those undergoing abdominal surgeries, timely monitoring of postsurgical SU level, colchicine prophylaxis, and avoiding the overuse of PTPN may help prevent PRGFs.

Hyperuricemia and acute gout after laparoscopic sleeve gastrectomy

The aim of this study was to evaluate the prevalence of hyperuricemia and acute gout after laparoscopic sleeve gastrectomy (LSG). Risk factors for developing gout were also examined. Eighty-five patients underwent LSG were enrolled in this prospective study. Serum uric acid levels, gout attacks and total water levels % derived by bioimpedance were examined pre-operatively and 1 month post-operatively. Hyperuricemia was identified in 30.6% pre-operatively and in 18.82% of patients post-operatively. From the patients' group with pre-operative hyperuricemia, 53.9% were normalized, 46.2% had increased uric acid post-operatively while gout was observed in 11.5%. From the patients group without pre-operative hyperuricemia, hyperuricemia and gout were observed in 6.8% and 5.1% post-operatively, respectively. The relative risk for developing hyperuricemia was 6.2 (95% confidence interval [CI] 2.2-17.8) and for developing gout was 2.3 (95% CI 2.2-17.8). Statistical significant differences for gout among the groups with and without gout were indicated concerning pre-operative use of medications (P < 0.001), age (P = 0.025), post-operative uric acid levels (P < 0.001) and post-operative total water levels % (P = 0.048). The prevalence of hyperuricemia was 18.8% and gout attack of 7.1% 1 month after LSG. From the cohort of patients with pre-operative hyperuricemia, a significant proportion normalized uric acid, while 11.5% developed gout. Patients without hyperuricemia pre-operatively developed hyperuricemia and gout in 6.8% and 5.1% post-operatively, respectively. The patients who had gout were younger and had 37% water levels post-operatively.

Longitudinal assessment of renal function in native kidney after bariatric surgery

The epidemic of obesity parallels that of chronic kidney disease (CKD). Obesity worsens the course of CKD, mainly defined by an abnormal glomerular filtration rate (GFR). Patients with severe obesity stages (II and III with body mass index >35 kg/m²) are eligible for bariatric surgery (BS), which is the most efficient method of achieving durable weight loss. BS may reverse glomerular hyperfiltration and albuminuria, improve adipocytokine profile, and relieve diabetes and hypertension. Obesity remission after BS might prevent the progression of renal failure in populations with morbid obesity. However, evidence for the beneficial effect of BS on renal function is scant. This lack of knowledge is mainly due to methodologic reasons, which are addressed in this review. The reversibility of hyperfiltration due to the presence of functional renal reserve hampers the interpretation of changes in true GFR after BS. This true GFR is only obtained with the renal clearance of an exogenous filtration marker. Estimation of GFR is generally provided by prediction equations, namely by modification of diet in renal diseases or by chronic kidney disease-epidemiology collaborative group. These equations are not accurate because the serum levels of both creatinine and cystatin C depend on extrarenal factors, which are modified by BS. Comparing the slopes of measured GFR according to various durations of exposure with morbid obesity would be critical in providing reliable data. Herein, we review the current knowledge on the effects of BS on kidney function; we specify the methodologic issues and particularities of the dietary management of CKD patients to propose reliable directions for future clinical research.