The effect of weight loss on plasma and urinary uric acid and lipid levels

Impact of Sleeve Gastrectomy on Uric Acid Levels in Patients with Obesity: A Comparative Study

PURPOSE

This study aimed to investigate the incidence of hyperuricemia in obese individuals with or without metabolic syndrome and assess the impact of sleeve gastrectomy surgery on the amelioration of hyperuricemia and metabolic syndrome.

MATERIALS AND METHODS

A prospective study was conducted on patients with obesity who were candidates for laparoscopic sleeve gastrectomy. These patients were diligently followed for 1 year after the surgical procedure. The assessment of hyperuricemia and metabolic syndrome was carried out both before and one year after the surgery.

RESULTS

A total of 198 patients (30 males and 168 females) underwent sleeve gastrectomy. After 1 year, there was a notable decline in the prevalence of hyperuricemia, decreasing from 77 to 36 cases (a reduction of 46.75%) among females and from 18 to 8 cases (a reduction of 44.44%) among males. Prior to the surgery, 60.6% of patients (120 out of 198) were diagnosed with metabolic syndrome, and 36.7% of these patients exhibited improvements in their metabolic syndrome status. Among individuals with metabolic syndrome, significant enhancements were observed in various anthropometric and laboratory measurements, including reductions in hypertriglyceridemia, hyperuricemia, and hypercholesteremia. A logistic regression analysis revealed that in females, changes in creatinine, glomerular filtration rate (GFR), weight loss, body mass index (BMI), and triglyceride reduction all had a notable impact on the likelihood of recovering from hyperuricemia.

CONCLUSION

These findings underscore the clinical relevance of this surgical intervention in managing obesity-related conditions.

Branched-chain α-keto acids and glutamate/glutamine: Biomarkers of insulin resistance in childhood obesity

OBJECTIVES

Insulin resistance (IR) in adolescents with obesity is associated with a sex-dependent metabolic 'signature' comprising the branched-chain amino acids (BCAAs), glutamate/glutamine, C3/C5 acylcarnitines and uric acid. Here, we compared the levels of branched-chain α-keto acids (BCKAs) and glutamate/glutamine, which are the byproducts of BCAA catabolism and uric acid among adolescents with obesity prior to and following a 6-month lifestyle-intervention program.

METHODS

Fasting plasma samples from 33 adolescents with obesity (16 males, 17 females, aged 12-18 year) were analysed by flow-injection tandem MS and LC-MS/MS. Multiple linear regression models were used to correlate changes in BCKAs, glutamate/glutamine and uric acid with changes in weight and insulin sensitivity as assessed by HOMA-IR, adiponectin and the ratio of triglyceride (TG) to HDL. In predictive models, BCKAs, glutamate/glutamine and uric acid at baseline were used as explanatory variables.

RESULTS

Baseline BCKAs, glutamate/glutamine and uric acid were higher in males than females despite comparable BMI-metrics. Following lifestyle-intervention, α-keto-β-methylvalerate (α-KMV, a metabolic by product of isoleucine) decreased in males but not in females. The ratio of BCKA/BCAA trended lower in males. In the cohort as a whole, BCKAs correlated positively with the ratio of TG to HDL at baseline and HOMA-IR at 6-month-follow-up. Glutamate/glutamine was positively associated with HOMA-IR at baseline and 6-month-follow-up. A reduction in BCKAs was associated with an increase in adiponectin, and those with higher BCKAs at baseline had higher adiponectin levels at 6-month-follow-up. Interestingly those adolescents with higher uric acid levels at baseline had greater reduction in weight.

CONCLUSIONS

BCKAs and glutamate/glutamine may serve as biomarkers of IR in adolescents with obesity, and uric acid might serve as a predictor of weight loss in response to lifestyle-intervention. Differential regulation of BCAA catabolism in adolescent males and females implicates critical roles for sex steroids in metabolic homeostasis.

Dietary Interventions for Gout and Effect on Cardiovascular Risk Factors: A Systematic Review

Gout is one of the most prevalent inflammatory rheumatic disease. It is preceded by hyperuricemia and associated with an increased risk for cardiovascular disease, both related to unhealthy diets. The objective of this systematic review is to better define the most appropriate diet addressing both disease activity and traditional cardiovascular risk factors in hyperuricemic patients. We included clinical trials with patients diagnosed with hyperuricemia or gout, investigating the effect of dietary interventions on serum uric acid (SUA) levels, gout flares and—if available—cardiovascular risk factors. Eighteen articles were included, which were too heterogeneous to perform a meta-analysis. Overall, the risk of bias of the studies was moderate to high. We distinguished four groups of dietary interventions: Calorie restriction and fasting, purine-low diets, Mediterranean-style diets, and supplements. Overall, fasting resulted in an increase of SUA, whilst small (SUA change +0.3 to −2.9 mg/dL) but significant effects were found after low-calorie, purine-low, and Mediterranean-style diets. Studies investigating the effect on cardiovascular risk factors were limited and inconclusive. Since Mediterranean-style diets/DASH (Dietary Approach to Stop Hypertension) have shown to be effective for the reduction of cardiovascular risk factors in other at-risk populations, we recommend further investigation of such diets for the treatment of gout.

Characterization of a novel alkaline Arxula adeninivorans urate oxidase expressed in Escherichia coli and its application in reducing uric acid content of food

This study reported a novel highly active alkaline urate oxidase (UOX) and demonstrated its application in reducing uric acid content of food under alkaline conditions. The UOX gene was cloned from Arxula adeninivorans NBRC 10858, and its N-terminally his₆-tagged form (rUOX) was overexpressed in Escherichia coli. The rUOX displayed maximal activity at 40 °C and pH 10, kept more than 90% initial activity under alkaline conditions (pH 9-11) and more than 80% at temperatures below 55 °C. The apparent K_m, turnover number (k_cat) and catalytic efficiency (k_cat/K_m) values for the substrate uric acid were respective 29.15 µM, 151.16 s^-1 and 5.19 s^-1. μM^-1, which are improvements over previously reported UOXs. The rUOX efficiently reduced uric acid and purine contents in beer, beef and yeast extract at pH 10, indicating a promising application in food with low purine and uric acid contents to prevent hyperuricemia and gout.

Nonpharmacological Management of Gout and Hyperuricemia: Hints for Better Lifestyle

We reviewed lifestyle factors that influence serum uric acid levels and risk of gout flare, and how to improve their deleterious effects. Since obesity increases uric acid and weight gain increases gout risk, weight reduction by daily exercise and limiting intake of excess calories is recommended. However, strenuous exercise, which causes adenine nucleotide degradation; starvation, which decreases uric acid excretion; and dehydration may raise the level of uric acid in serum and trigger gout. Increased intake of purine-rich foods, such as meat and seafood, raise the level of uric acid in serum and is associated with increased risk of gout, whereas dairy products, especially low-fat types, are associated with a lower risk of gout. Also, heavy alcohol drinking raises the uric acid level and increases the risk of gout through adenine nucleotide degradation and lactate production. Sweet fruits and soft drinks containing fructose should be moderated, since fructose may raise uric acid and increase gout risk through uric acid production and/or decreased excretion. On the other hand, the Mediterranean diet is recommended for gout patients, since it may also help prevent hyperuricemia. Furthermore, coffee and vitamin C supplementation could be considered as preventive measures, as those can lower serum uric acid levels as well as the risk of gout.

Effect of visceral fat accumulation on uric acid metabolism in male obese subjects: visceral fat obesity is linked more closely to overproduction of uric acid than subcutaneous fat obesity

We investigated the relationship between uric acid (UA) metabolism and fat distribution in 36 obese men with a mean +/- SD age of 38 +/- 16 years and mean body-mass index (BMI) of 34 +/- 4 kg/m2. Subjects were divided into two groups: subcutaneous fat obesity (SFO) and visceral fat obesity (VFO), according to their abdominal fat distribution based on the results of computed tomography (CT). SFO was defined as having a ratio of visceral fat area (VFA) to subcutaneous fat area (V/S) of less than 0.4, and VFO was defined as having a V/S ratio > or = 0.4. The levels of serum total cholesterol (T-Chol), triglyceride (TG), and fasting plasma glucose (FPG), and the diastolic blood pressure (dBP) were significantly higher in the VFO group than in the SFO group. Serum UA levels were much higher in both the SFO and VFO groups than in the non-obese control group (492 +/- 107 and 474 +/- 90 v 309 +/- 48 micromol/L, respectively). The 24-hour urinary urate excretion (u-UA24h) and the UA clearance (Cua) to creatinine clearance (Ccr) ratio were significantly higher in the VFO group than in the SFO group (3.75 +/- 1.43 v 2.69 +/- 1.12 mmol/d, P < .05; and 5.9% +/- 2.0% v 3.6% +/- 1.7%, P < .001, respectively). The frequency of hyperuricemia was markedly higher in both the SFO and VFO groups compared with the control group (71% and 73% v 0%, respectively). Although the high serum UA level seemed to be related to low u-UA24h in 80% of SFO subjects with hyperuricemia, this was the case in only 10% of VFO subjects. While 44% of VFO subjects with hyperuricemia were designated as an overproduction type. These results suggest that the mechanism of hyperuricemia in obesity may be affected by the difference in body fat distribution and that the assessment of body fat distribution and types of hyperuricemia is crucial for the treatment of obese patients with hyperuricemia.

Mechanism and treatment of hypertriglyceridaemia in gout

Using the Intralipid lipid tolerance test we could not demonstrate any direct effect of serum triglyceride on uric acid or any influence of hyperuricaemia on triglyceride removal. This result supports previous studies suggesting that hyperuricaemia and hypertriglyceridaemia are linked through the association of obesity and alcohol excess rather than a direct cause and effect mechanism. It was possible to demonstrate significant reductions of serum triglyceride in patients with gout by reducing either their alcohol intake or body weight. Reduction of serum uric acid by probenecid had no effect on serum triglyceride or cholesterol. Similarly, allopurinol had no significant effect on serum triglyceride, but a significant fall of serum cholesterol was observed.