Comparison of 24-hour urine composition prior to and after stone removal in nephrolithiasis: a prospective observational study.

BACKGROUND: To evaluate 24-hour urine composition prior to and after complete stone removal in nephrolithiasis patients to determine potential relationship between kidney stones and patient metabolic status. METHODS: A prospective observational study was performed with patient enrollment from March 2019 to August 2020. 24-hour urine samples were collected prior to stone removal and 4 weeks after double-J stent removal, and examined the following urinary parameters: volume, creatinine, sodium, calcium, uric acid, citrate, oxalate, potassium, phosphorous, magnesium, and pH value. For each parameter, pairwise t test was performed to compare samples prior to and after stone removal. The number of cases that changed from normal to abnormal or vice versa was also evaluated for each parameter. The study was registered at http://clinicaltrials.gov/ (NCT03846011). RESULTS: A total of 109 patients completed 24-hour urine collections prior to and after stone removal. The urinary calcium and phosphate levels increased significantly after stone removal, showing a mean difference of 0.55 mmol (P=0.015) and 2.35 mmol (P=0.001) respectively. None of the other urinary parameters demonstrated a statistically significant difference when means were compared. The percentage differences for all urinary parameters ranged from 5.4% to 14.1%. The percentages of patients that presented clinically significant changes in urinary parameter values from normal to abnormal or vice versa ranged from 4.6% to 20.1%. CONCLUSIONS: Ideally, evaluation of 24-hour urine compositions should be undertaken after total stone removal, especially for patients with calcium stones. For patients who cannot achieve total stone removal, 24-hour urine samples should be thoroughly interpreted as urinary calcium and phosphate levels might be depleted in the presence of urinary stones.

Alteration of the gut microbiota by vinegar is associated with amelioration of hyperoxaluria-induced kidney injury.

Hyperoxaluria is well known to cause renal injury and end-stage kidney disease. Previous studies suggested that the renal function of rats with hyperoxaluria was improved after dietary vinegar intake. However, its underlying mechanisms remain largely unknown. The aim of the present study was to examine changes of gut microbiota and blood and urinary metabolites that associate with changes in kidney function to identify mechanisms involved with vinegar induced amelioration of hyperoxaluria-induced kidney injury. Using an ethylene glycol (EG)-induced hyperoxaluria rat model, we evaluated the effects of the vinegar on renal injury. Oral administration of vinegar (2 ml kg-1 day-1) reduced the elevated serum creatinine, BUN, and protected against hyperoxaluria-induced renal injury, renal fibrosis, and inflammation. Gut microbiota analysis of 16S rRNA gene in the hyperoxaluria-induced renal injury rats showed that vinegar treatment altered their microbial composition, especially the recovery of the levels of the Prevotella, Ruminiclostridium, Alistipes and Paenalcaligenes genus, which were significantly increased in the hyperoxaluria-induced renal injury rats. Additionally, liquid chromatography-mass spectrometry (LC-MS)-based metabolome analysis showed that total of 35 serum and 42 urine metabolites were identified to be associated with protective effects of vinegar on hyperoxaluria-induced renal injury rats. Most of these metabolites were involved in thiamine metabolism, glycerol phosphate shuttle, biotin metabolism, phosphatidylcholine biosynthesis and membrane lipid metabolism. Importantly, the effects of vinegar against renal injury were weakened after depletion of gut microbiota by antibiotic treatment. These results suggest that vinegar treatment ameliorates the hyperoxaluria-induced renal injury by improving the gut microbiota and metabolomic profiles.

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.

A prospective and randomised trial comparing fluoroscopic, total ultrasonographic, and combined guidance for renal access in mini-percutaneous nephrolithotomy.

OBJECTIVE: To compare the safety and efficacy of fluoroscopic guidance (FG), total ultrasonographic guidance (USG), and combined ultrasonographic and fluoroscopic guidance (CG) for percutaneous renal access in mini-percutaneous nephrolithotomy (mini-PCNL). PATIENTS AND METHODS: The present study was conducted between July 2014 and May 2015 as a prospective randomised trial at the First Affiliated Hospital of Guangzhou Medical University. In all, 450 consecutive patients with renal stones of >2 cm were randomised to undergo FG, USG, or CG mini-PCNL (150 patients for each group). The primary endpoints were the stone-free rate (SFR) and blood loss (haemoglobin decrease during the operation and transfusion rate). Secondary endpoints included access failure rate, operating time, and complications. S.T.O.N.E. score was used to document the complexity of the renal stones. The study was registered at http://clinicaltrials.gov/ (NCT02266381). RESULTS: The three groups had similar baseline characteristics. With S.T.O.N.E. scores of 5-6 or 9-13, the SFRs were comparable between the three groups. For S.T.O.N.E. scores of 7-8, FG and CG achieved significantly better SFRs than USG (one-session SFR 85.1% vs 88.5% vs 66.7%, P = 0.006; overall SFR at 3 months postoperatively 89.4% vs 90.2% vs 69.8%, P = 0.002). Multiple-tracts mini-PCNL was used more frequently in the FG and CG groups than in the USG group (20.7% vs 17.1% vs 9.5%, P = 0.028). The mean total radiation exposure time was significantly greater for FG than for CG (47.5 vs 17.9 s, P < 0.001). The USG had zero radiation exposure. There was no significant difference in the haemoglobin decrease, transfusion rate, access failure rate, operating time, nephrostomy drainage time, and hospital stay among the groups. The overall operative complication rates using the Clavien-Dindo grading system were similar between the groups. CONCLUSIONS: Mini-PCNL under USG is as safe and effective as FG or CG in the treatment of simple kidney stones (S.T.O.N.E. scores 5-6) but with no radiation exposure. FG or CG is more effective for patients with S.T.O.N.E. scores of 7-8, where multiple percutaneous tracts may be necessary.