Managing Gout in the Patient with Renal Impairment

The Occurrence of Nephrolithiasis in Gout Patients: A Longitudinal Follow-Up Study Using a National Health Screening Cohort

The association of gout with nephrolithiasis has been suggested. The current study investigated the risk of nephrolithiasis in patients with gout. The relationship of nephrolithiasis with gout was assessed according to patient characteristics. Individuals in the Korean National Health Insurance Service−Health Screening Cohort were examined. The 17,043 participants with gout were paired with 68,172 comparison participants. The diagnosis of nephrolithiasis was examined in both the gout and control groups. The possible risk of nephrolithiasis in the gout group was analyzed using a stratified Cox proportional hazards model. Subcategory analyses were conducted according to demographic features and comorbidities. The rate of nephrolithiasis was 3.3% (569/17,043) in the gout group and 2.6% (1786/68,172) in the control group. The adjusted hazard ratio (aHR) of gout for nephrolithiasis was 1.23 (95% confidence intervals [95% CI] = 1.12−1.36) in the overall study population. The < 60 years and male groups showed an increased risk of nephrolithiasis related to gout (aHR = 1.26 [1.13−1.42] for the < 60 years group; aHR = 1.27 [1.15−1.41] for the male group). Regarding comorbidities, all subgroups except for the underweight, overweight, total cholesterol ≥ 240 mg/dL, fasting blood glucose ≥ 100 mg/dL, and CCI score 1 and ≥ 2 groups showed a higher risk of nephrolithiasis in gout patients. The gout patients presented an increased occurrence of nephrolithiasis. The middle-aged, male, and healthy populations showed consistently higher HRs of nephrolithiasis related to gout.

Treating gout - can hypouricemia produced by moderate doses of combined oral treatment give early treatment success? Preliminary observations

Six male patients with gout were treated with combined oral medication (febuxostat, 120 mg/d, and benzbromarone, 50 or 100 mg/d), aiming at a more rapid success of uric acid lowering treatment (ULT) compared to guideline suggestions. By combined oral medication in moderate dosage, the sUA was reduced to <2 mg/dl in all cases. We conclude that, by the treatment schedule outlined, the majority of patients with gout can be cured within 1 - 2 years, with uricase treatment being necessary very rarely only.

Multi modular toxicity assessment of nephrotoxicity in podophyllotoxin exposure rats on account of toxicological evidence chain (TEC) concept

Early diagnosis of kidney injuries caused by herbs is necessary to enable effective treatments, prevent kidney failure and promote the internationalization and modernization of herbal medicine. Whereas the toxic assessment evidence has not integrated yet, and the evaluation method has not been unanimously agreed. For example, the gold standard assessing toxicity in animals remains to be histopathology, but serum biochemical indexes are the primary measures for monitoring organs dysfunction in humans. In this study, using Sprague Dawley rats, we investigated whether integrated analyses of transcriptomic and metabolomic data with toxicological evidence chain (TEC) concept could identify indicators of injury and provide new insights into the mechanisms of nephrotoxicity. Firstly, the objective phenotype of the animals was observed in detail and the toxicity performance was collected after administration. Subsequently, histopathological examination and serum biochemical toxicity evidence were collected. Next, we obtained concurrent measurements of transcriptomic changes in kidneys, and changes along with metabolic profiles in serum, after exposure to PT(Podophyllotoxin) to acquire evidence at the molecular level. Last but not least, the GTEA (Grades of Toxicological Evidence Assessment) based on GRADE(Grading of Recommendations Assessment, Development, and Evaluation) system was used to evaluate toxic evidence which can be assigned to a toxic level. The orally gavaged rats with PT have been confirmed with dose-dependent kidney damage from 5 to 15 mg/kg after 4 d. Our findings suggest that the main pathological changes occurred in Glycerophosphatidylcholine metabolism, Arachidonic acid metabolism, Energy metabolism, Tyrosine metabolism, Tryptophan metabolism and so on.Moreover, the alteration of the potential metabolites lipid (i.e. LPC, palmitic acid) and sulfate could serve as plausible markers of PT-induced kidney injury. Our approach provides a mechanistic framework for the refinement of the grading standard of toxicity evidence, which is applicable to other toxicants originated from herbal medicine based on multi-omics data.

Excess Uric Acid Induces Gouty Nephropathy Through Crystal Formation: A Review of Recent Insights

Uric acid (UA) is the final product of purine metabolism in the human body, and impaired purine metabolism can increase the uric acid in serum, finally resulting in hyperuricemia (HUA). Current evidences suggest that urates might have antioxidant properties under certain circumstances, but most evidences suggest that urates promote inflammation. Hyperuricemia leads to the formation of urate crystals, which might be recognized as a red flag by the immune system. Such a response stimulates macrophage activation, leads to the activation of NOD-like receptor protein 3 (NLRP3) inflammasome vesicles, and ultimately the production and liberation of interleukin-1b (IL-1b) and interleukin-18 (IL-18), which can mediate inflammation, apoptosis and necroinflammation and cause an inflammatory cascade response. The kidney is one of the most commonly affected organs in HUA, which promotes the development of chronic kidney disease (CKD) by damaging endothelial cells, activating the renin-angiotensin system (RAS), and promoting inflammatory responses. Pharmacological interventions and lifestyle modifications are the primary means for controlling gout and lowering UA. The febuxostat is safe for CKD patients in the UA lowering therapy. Although dialysis can reduce UA levels, the application of drug is also necessary for dialysis patients. This article reviews the synthesis and metabolism of UA, etiology of HUA, the relationship between HUA and kidney disease, the treatment of gout and gouty nephropathy (GN).

Correlation of Serum Cystatin C with Renal Function in Gout Patients with Renal Injury

The gout-induced continuous deposition of urate in the kidney tissues is the main cause of renal injury, for which cystatin C (Cys C) is an important indicator. This research analyzed the correlation between general renal injury indicators and serum Cys C level, and further investigated the potential of Cys C in renal injury diagnosis. A total of 140 gout patients with renal injury (GRI) were recruited and grouped by their glomerular filtration rate (GFR). Urea nitrogen, uric acid, creatinine, and Cys C levels in the serum were evaluated. The diagnostic efficacy of serum Cys C was evaluated by the nonparametric receiver operating characteristic analysis. Serum Cys C level was increased with decreased GFR in GRI. Urea nitrogen, uric acid, and creatinine levels in the serum showed positive correlations with Cys C level. The area under the curve for serum Cys C was 0.8589 (P < 0.001). In conclusion, this research demonstrated that the serum Cys C level was a precise diagnostic marker for GFR and renal damage evaluation, and showed a significant diagnostic value for renal injury in patients with gout.

Urate levels and clearance in renal patients under peritoneal dialysis

Hemodialysis adequately controls serum uric acid (UA) levels, making UA-lowering drugs unnecessary; scant data are available for peritoneal dialysis (PD). We analyzed blood, 24 h urine and dialysis fluid from twenty patients under PD, to assess UA levels and clearances, and factors associated with better performance and maintenance of target levels (<6mg/dL). Median serum UA was 5.4 mg/dL (p25-75 4.4-5.8), mainly achieved through peritoneal clearance (3.0 mL/min/1.73m2, 71.2% of total UA clearance); 75% of participants was on UA targets. Continuous cycling peritoneal dialysis showed highest UA clearance and target achievements. These findings may be of interest for end-stage renal patients with gout.

Multiple-Purpose Connectivity Map Analysis Reveals the Benefits of Esculetin to Hyperuricemia and Renal Fibrosis

Hyperuricemia (HUA) is a risk factor for chronic kidney disease (CKD). Serum uric acid (SUA) levels in CKD stage 3–4 patients closely correlate with hyperuricemic nephropathy (HN) morbidity. New uric acid (UA)-lowering strategies are required to prevent CKD. The multiple-purpose connectivity map (CMAP) was used to discover potential molecules against HUA and renal fibrosis. We used HUA and unilateral ureteral occlusion (UUO) model mice to verify renoprotective effects of molecules and explore related mechanisms. In vitro experiments were performed in HepG2 and NRK-52E cells induced by UA. Esculetin was the top scoring compound and lowered serum uric acid (SUA) levels with dual functions on UA excretion. Esculetin exerted these effects by inhibiting expression and activity of xanthine oxidase (XO) in liver, and modulating UA transporters in kidney. The mechanism by which esculetin suppressed XO was related to inhibiting the nuclear translocation of hexokinase 2 (HK2). Esculetin was anti-fibrotic in HUA and UUO mice through inhibiting TGF-β1-activated profibrotic signals. The renoprotection effects of esculetin in HUA mice were associated with lower SUA, alleviation of oxidative stress, and inhibition of fibrosis. Esculetin is a candidate urate-lowering drug with renoprotective activity and the ability to inhibit XO, promote excretion of UA, protect oxidative stress injury, and reduce renal fibrosis.