Correlation between serum Klotho and uromodulin expression levels and IgA nephropathy complicated with hyperuricemia

Objective  To explore the correlation between the expression levels of serum Klotho and uromodulin （UMOD） and immunoglobulin A （IgA） nephropathy complicated with hyperuricemia.

Methods  From January 1, 2018 to January 1, 2022, 97 hospitalized IgA nephropathy were selected as study subjects. Based upon blood uric acid level before renal puncture, they were assigned into two groups of IgA nephropathy complicated with hyperuricemia （n=42） and normal blood uric acid （n=55）. Additionally, 97 healthy individuals during the same period were designated as control group. Serum levels of Klotho and UMOD and basic profiles of three groups were compared. Pearson’s method was applied for examining the correlation between serum levels of Klotho and UMOD, estimated glomerular filtration rate （eGFR）, uric acid and creatinine levels in patients with IgA nephropathy complicated by hyperuricemia. Multivariate Logistic regression was utilized for analyzing the influencing factors of IgA nephropathy complicated with hyperuricemia. Receiver operating characteristic （ROC） curve was employed for examining the diagnostic value of serum levels of Klotho and UMOD for IgA nephropathy complicated with hyperuricemia.

Results  Serum Klotho was （151.66±27.29） ng/L and serum UMOD （39.65±8.67） g/L in IgA nephropathy complicated with hyperuricemia group; serum Klotho was （185.34±38.17） ng/L and serum UMOD （51.13±12.32） g/L in normal blood uric acid group; serum Klotho was （211.53±50.63） ng/L and serum UMOD （62.39±16.86） g/L in control group. Statistically significant differences existed in serum levels of Klotho and UMOD among three groups （P＜0.05）. Systolic blood pressure was （152.62±18.82） mmHg（1mmHg=0.133 kPa）, diastolic blood pressure （98.37±13.65）mmHg, proportion of hypertension 27（64.29）, 24-hour urine protein quantification （2.55±0.69）g, blood uric acid （435.26±113.25）μmol/L, creatinine （352.55±58.62） μmol/L and eGFR （72.28±13.53）mL·min⁻¹·（1.73m²）⁻¹ in IgA nephropathy complicated with hyperuricemia group; systolic blood pressure was （112.58±15.97）mmHg, diastolic blood pressure （72.43±10.34）mmHg, proportion of hypertension 21（38.18）, 4-hour urine protein quantification （1.62±0.31）g, blood uric acid （342.59±84.64）μmol/L, creatinine （103.11±27.47）μmol/L and eGFR （102.96±35.68）mL·min⁻¹·（1.73m²）⁻¹ in normal blood uric acid group. The inter-group differences of the above parameters were statistically significant （P＜0.05）. Pearson’s correlation analysis results indicated that serum levels of Klotho and UMOD in patients with IgA nephropathy complicated by hyperuricemia were correlated negatively with blood uric acid and creatinine and positively with eGFR（P＜0.05）; hypertension, 24-hour urine protein quantification, eGFR, blood uric acid and serum levels of Klotho and UMOD were independent influencing factors for IgA nephropathy complicated with hyperuricemia （P＜0.05）. ROC curve showed that area under the curve （AUC） of serum Klotho and UMOD for diagnosing IgA nephropathy complicated by hyperuricemia alone and in combination was 0.947, 0.882 and 0.961 respectively and combined diagnostic value of the two was higher than that of single diagnosis（Z_{combination-Klotho}=0.887,P=0.375; Z_{combination-UMOD}=2.423, P=0.015）.

Conclusion  Serum levels of Klotho and UMOD are down-regulated in patients with IgA nephropathy complicated by hyperuricemia. Correlation exists between IgA nephropathy and hyperuricemia and a combined diagnosis has an excellent effect. Close monitoring of serum levels of Klotho and UMOD has some reference value for diagnosing IgA nephropathy complicated by hyperuricemia.