Relationship between nephrolithiasis and dyslipidemia in primary gout patients

Abstract

Objective To explore the impact of dyslipidemia on uric acid stones by analyzing the relationship between blood lipids and urolithiasis in primary gouty patients. Methods We retrospectively identified patients with nephrolithiasis in primary gout patients who underwent stone chemical analysis, compared with gout patients without nephrolithiasis. The clinical parameters, urine analysis and lipid levels were analyzed. Patients were divided into groups based on serum lipid levels. The groups were compared based on demographic data and stone composition. Correlations were analyzed between serum lipid, urinary pH and uric acid stones. Moreover, the risk factors of uric acid stones were determined by logistic regression analysis. Analysis of variance, t-test, chi-square test, Spearman′s test and Logistic regression were used for statistical analysis. Results ① A total of 144 gout patients were included in study, 48 patients with urolithiasis and 96 patients without urolithiasis. ② Serum lipid levels were significantly lower in urolithiasis group than those patients without urolithiasis including triglyceride (TG) [1.6(0.9, 2.1) mmol/L vs 2.2(1.4, 3.2) mmol/L, Z=2.38, P=0.01], total cholesterol (TC) [(4.4±1.2) mmol/L vs (5.1±1.0) mmol/L, t=5.3, P=0.006]; low density lipoprotein cholesterol(LDL-C) [(2.5±0.9) mmol/L vs (3.2±0.9) mmol/L, t=4.2, P=0.005]. ③ Compared to oxalate stone formers, uric acid stone formers had significantly higher TG [(1.8±0.6) mmol/L vs (0.9±0.5) mmol/L, t=4.9, P=0.001), TC [(4.4±1.1) mmol/L vs (3.8±1.0) mmol/L, t=1.8, P=0.001] and LDL-C [(2.8±0.9) mmol/L vs (2.0±0.7) mmol/L, t=3.5, P=0.045], while the high density lipoprotein (HDL) level was lower [(0.94±0.23) mmol/L vs (1.32±0.41) mmol/L, t=-4.0, P=0.002]. ④ Percentage of uric acid stones in high TG group was higher than normal TG group [85% (17/20 vs 46.4% (13/28) , χ2=7.4, P=0.007], in addition, the percentage of uric acid stones in low HDL group was higher than normal HDL group [(82.1% (23/28) vs 35.0% (7/20) , χ2=11.1, P=0.001]. ⑤ Uric acid stones were significantly correlated with high TG, low LDL and urinary pH(r=0.522, 0.47, -0.212, respectively). Logistic analysis showed risk factors for uric acid stone in primary gouty patients were high TG [OR=2.38, 95%CI(1.41, 13.7); P=0.01] and lower HDL level [OR=0.01, 95%CI(0.01, 0.43); P=0.01]. Conclusion There is a link between dyslipidemia and kidney uric acid stone risk in primary gout patients. Specific alterations in patient′s lipid profile may portend unique aberrations in urine physico-chemistry and uric acid stone risk. Key words: Gout; Kidney; Nephrolithiasis; Dyslipidemia; Body mass index