Impact of dyslipidemia on 24-h urine composition in adults without urolithiasis

A cross-sectional analysis of the relationship between the non-high density to high density lipoprotein cholesterol ratio (NHHR) and kidney stone risk in American adults

BACKGROUND

Recent interest in the Non-High Density to High Density Lipoprotein Cholesterol ratio (NHHR) has emerged due to its potential role in metabolic disorders. However, the connection between NHHR and the development of kidney stones still lacks clarity. The primary goal of this research is to explore how NHHR correlates with kidney stone incidence.

METHODS

An analysis was conducted on the data collected by the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018, focusing on adults over 20 years diagnosed with kidney stones and those with available NHHR values. Employing weighted logistic regression and Restricted Cubic Spline (RCS) models, NHHR levels' correlation with kidney stone risk was examined. Extensive subgroup analyses were conducted for enhanced reliability of the findings.

RESULTS

The findings indicate a heightened kidney stone risk for those at the highest NHHR levels relative to those at the lowest (reference group). A notable non-linear correlation of NHHR with kidney stone incidence has been observed, with a significant P-value (< 0.001), consistent across various subgroups.

CONCLUSION

A clear link exists between high NHHR levels and increased kidney stone risk in the American adult population. This study highlights NHHR's significance as a potential indicator in kidney stone formation.

Meta-analysis guided development of a standard artificial urine

In this study, we present the first meta-analysis of human urine reported in the literature, drawing data from a total of 35 articles with a combined participant count of 14,021. Through this analysis, we have developed an artificial urine (AU) composition that can be adjusted within typical physiological parameters for in vitro applications. Our findings demonstrate the utility of this AU in determining the solubility of nitrofurantoin, particularly in the context of crystalluria. Notably, we observe that in saline, nitrofurantoin solubility, within the framework of its urinary pharmacokinetics, suggests a risk of crystalluria. However, in AU, this risk is mitigated due to complexation with urea. More broadly, we anticipate that our developed formulation will serve as a foundation for translational studies across biomedical and pharmaceutical sciences.

The association of visceral adiposity index with the risk of kidney stone and kidney stone recurrence

AIM

Our aim in this study was primarily to assess the relationship between visceral adiposity index (VAI) and the risk of kidney stones and kidney stone recurrence in US adults.

METHODS

We used data from the National Health and Nutrition Examination Survey (NHANES) 2007-2014 for our analysis. VAI was calculated from waist circumference (WC), body mass index (BMI), triglycerides (TG), and high-density lipoprotein-cholesterol (HDL-C). Kidney stones and recurrence of kidney stones were obtained from questionnaire interview data. We used multivariate logistic regression analysis to explore the correlation between VAI and the risk of kidney stone and kidney stone recurrence. In addition, we performed subgroup analysis, interaction tests, and restricted cubic spline (RCS) analysis.

RESULTS

A total of 9886 participants were included in this study, with a prevalence of 9.24% for kidney stones and 2.97% for recurrence of kidney stones. The prevalence of kidney stones and kidney stone recurrence increased with higher quartiles of VAI. We observed a significantly positive correlation between VAI and the risk of kidney stone and kidney stone recurrence. Participants with the highest VAI quartiles had a 48% (OR: 1.48, 95%CI: 1.08-2.02) and 52% (OR: 1.52, 95%CI: 0.86-2.71) increased risk of kidney stones and kidney stone recurrence, respectively, compared to participants with the lowest VAI quartiles. Subgroup analysis and interaction tests demonstrated this positive association independent of different subgroup factors.

CONCLUSION

Visceral fat accumulation may be associated with an increased risk of kidney stones and kidney stone recurrence.

Association between urinary sodium and circulating lipid levels: a Mendelian randomization study

Background

Urinary sodium was indicated to be associated with dyslipidemia, but inconsistent conclusions for this association exist across the present observational studies.

Objectives

This study aimed to evaluate the causal association between urinary sodium and circulating lipid levels [low-density lipoprotein cholesterol (LDL-C), triglycerides, and high-density lipoprotein cholesterol (HDL-C)] through Mendelian randomization.

Methods

Univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) with pleiotropy-resistant methods were performed. Data for urinary sodium were obtained from the genome-wide association study (GWAS) from 446,237 European individuals. Data for lipid profiles were extracted from GWAS based on the UK Biobank (for the discovery analysis) and the Global Lipids Genetics Consortium (for the replication analysis).

Results

In the discovery analysis, UVMR provided evidence that per 1-unit log-transformed genetically increased urinary sodium was associated with a lower level of HDL-C level (beta = -0.32; 95% CI: -0.43, -0.20; p = 7.25E-08), but not with LDL-C and triglycerides. This effect was still significant in the further MVMR when considering the effect of BMI or the other two lipid contents. In contrast, higher genetically predicted triglycerides could increase urinary sodium in both UVMR (beta = 0.030; 95% CI: 0.020, -0.039; p = 2.12E-10) and MVMR analyses (beta = 0.029; 95% CI: 0.019, 0.037; p = 8.13E-10). Similar results between triglycerides and urinary sodium were found in the replication analysis.

Conclusion

Increased urinary sodium may have weak causal effects on decreased circulating HDL-C levels. Furthermore, genetically higher triglyceride levels may have independent causal effects on increased urinary sodium excretion.

Glycine suppresses kidney calcium oxalate crystal depositions via regulating urinary excretions of oxalate and citrate

An abnormal urine composition is a key reason for kidney stone formation, but little is known about the roles of small metabolites in the urine during kidney stone formation. Here, we found urine glycine in patients with kidney calcium oxalate (CaOx) stone was significantly lower than that in healthy people via 1 H NMR spectra detection, and investigated the role and underlying mechanism of glycine in the regulation of CaOx stone formation. Our results showed that glycine could significantly attenuate ethylene glycol-induced CaOx crystal depositions in rat kidney via decreasing urine oxalate and increasing urine citrate. Mechanism studies revealed that glycine could decrease urine oxalate through downregulating Slc26a6 expression, whereas increase urine citrate via inhibiting Nadc1 expression. Moreover, glycine decreased the protein expression of both Slc26a6 and Nadc1 via increasing the expression of miRNA-411-3p, which directly bound to the 3'-untranslated regions of Slc26a6 and Nadc1 messenger RNAs, in vitro and in vivo. Together, our results revealed a novel role of glycine in the regulation of kidney CaOx crystal formation and provided a potential target for the treatment of kidney CaOx stone.

A randomized clinical trial evaluating the short-term results of ureteral stent encrustation in urolithiasis patients undergoing ureteroscopy: micro-computed tomography evaluation

Although many ureteral stents are commercially available, the actuality of encrustation is yet to be elucidated in humans. This study compared the Tria Ureteral Stent with PercuShield and the Polaris Ultra Ureteral Stent with HydroPlus Coating for short-term encrustation formation. Eighty-four patients, who required ureteral stent placement after ureteroscopy, were randomized into two stent groups. After stent removal on postoperative day 14, the encrustation volume on the stent surface was measured by micro-computed tomography. The primary outcome was the inner luminal encrustation volume. Secondary outcomes were encrustation volume on the outer or total surfaces and occurrence of adverse events. Clinical factors related to encrustation were also assessed as a post-hoc analysis. Finally, of the 82 patients analyzed, 75 (91.5%) had encrustation in the inner lumen of the stent. The difference in median inner encrustation volume between the Tria and Polaris Ultra stents was comparable (0.56 vs. 0.37 mm³, P = 0.183). There was no difference observed in the encrustation volume on the outer/total surfaces and stent-related adverse events. In both ureteral stents, the shaft body showed significant inner luminal encrustation compared to the proximal or distal loop (all, P < 0.05). Dyslipidemia (P = 0.027), elevated urine pH (P = 0.046), and crystalluria (P = 0.010) were associated with encrustation formation. The Tria and Polaris Ultra stents had similar efficacy for preventing encrustation in the short-term. Further studies are required to compare their long-term patency.

Statins significantly alter urinary stone-related urine biochemistry in calcium kidney stone patients with dyslipidemia

OBJECTIVE

To investigate whether the use of statins would alter 24-h urine biochemistry in male patients with calcium kidney stones.

METHODS

We prospectively recruited 78 male patients with calcium kidney stones between May 2017 and December 2017, and 30 male controls with matching sex and age, but without kidney stones. All patients were classified into higher- and lower-risk groups of atherosclerotic cardiovascular disease according to the American College of Cardiology/American Heart Association guidelines. Atorvastatin 20 mg per day was prescribed for 12 weeks to the higher risk patients. For kidney stone group, 24-h urine collections were carried out before and after statin therapy.

RESULTS

A total of 78 patients and 30 controls were included. Higher-risk patients had significantly higher urine uric acid and calcium levels than lower-risk patients. After atorvastatin treatment for 12 weeks, urine citrate significantly increased (P < 0.001) accompanied with increased urine pH (P < 0.001), whereas urine uric acid significantly decreased after treatment. Although urine oxalate significantly increased after treatment (P = 0.037), we did not find any significant difference in urine calcium, ion activity product of calcium oxalate and ion activity product of calcium phosphate.

CONCLUSION

These findings suggest that atorvastatin administration might increase urinary citrate and decrease urinary uric acid in patients with calcium kidney stones and dyslipidemia.

Association between hypertension and 24-h urine composition in adults without urolithiasis in China

PURPOSE

To explore the association between hypertension and 24-h urine composition in adults without urolithiasis in China.

MATERIALS AND METHODS

Blood test and 24-h urine analysis were performed on 958 non-stone formers in six cities to select eligible participants. Eligible participants were divided into hypertension group and non-hypertension group according to WHO guidelines. The 24-h urine compositions between two groups were compared using univariate and multivariate logistic regressions.

RESULTS

A total of 584 adults without urolithiasis were included in this analysis. Compared with non-hypertension group, hypertension group had significantly older age, higher BMI, higher prevalence of diabetes mellitus and higher levels of total cholesterol and LDL, but lower eCCr value, lower levels of serum creatinine and serum sodium (all P value < 0.05). In univariable comparisons, hypertension patients had significantly higher level of urine potassium (mean difference [MD] = - 3.89 mmol, 95% confidence interval [CI] - 7.37 to - 0.42, P = 0.014) but lower levels of urine creatinine (MD = 0.80 mmol, 95% CI 0.21-1.39, P = 0.004) and pH (MD = 0.12, 95% CI - 0.01 to 0.25, P = 0.033) than non-hypertension adults. However, no significant difference was found in all 24-h urinary components between two groups (all P value > 0.05) in multivariate Logistic regression analyses.

CONCLUSIONS

Our study demonstrated that hypertension did not independently influence the 24-h urine composition in adults without urolithiasis in China; however, we cannot make such an arbitrary conclusion that hypertension was not a risk factor for urolithiasis.

Dietary vinegar prevents kidney stone recurrence via epigenetic regulations

BACKGROUND

Epidemiological evidence of over 9000 people suggests that daily intake of vinegar whose principal bioactive component is acetic acid is associated with a reduced risk of nephrolithiasis. The underlying mechanism, however, remains largely unknown.

METHODS

We examined the in vitro and in vivo anti-nephrolithiasis effects of vinegar and acetate. A randomized study was performed to confirm the effects of vinegar in humans.

FINDINGS

We found individuals with daily consumption of vinegar compared to those without have a higher citrate and a lower calcium excretion in urine, two critical molecules for calcium oxalate (CaOx) kidney stone in humans. We observed that oral administration of vinegar or 5% acetate increased citrate and reduced calcium in urinary excretion, and finally suppressed renal CaOx crystal formation in a rat model. Mechanism dissection suggested that acetate enhanced acetylation of Histone H3 in renal tubular cells and promoted expression of microRNAs-130a-3p, -148b-3p and -374b-5p by increasing H3K9, H3K27 acetylation at their promoter regions. These miRNAs can suppress the expression of Nadc1 and Cldn14, thus enhancing urinary citrate excretion and reducing urinary calcium excretion. Significantly these mechanistic findings were confirmed in human kidney tissues, suggesting similar mechanistic relationships exist in humans. Results from a pilot clinical study indicated that daily intake of vinegar reduced stone recurrence, increased citrate and reduced calcium in urinary excretion in CaOx stone formers without adverse side effects.

INTERPRETATION

Vinegar prevents renal CaOx crystal formation through influencing urinary citrate and calcium excretion via epigenetic regulations. Vinegar consumption is a promising strategy to prevent CaOx nephrolithiasis occurrence and recurrence. FUND: National Natural Science Foundations of China and National Natural Science Foundation of Guangdong Province.