Associations Of Vitamin D Binding Protein And Klotho With Vitamin D Deficiency And Renal Tubular Injury In Serum Of Patients With Idiopathic Membranous Nephropathy

Objective:The levels of serum vitamin D binding protein?DBP?and Klotho were measured in idiopathic membranous nephropathy?IMN?patients.We aimed at analyzing whether serum DBP and Klotho are related to vitamin D deficiency and renal tubular injury and exploring factors related to vitamin D deficiency.Methods:124 biopsy-proven IMN patients and 112 healthy controls were enrolled from the nephrology and health screening centers of Shengjing Hospital of China Medical University from Sep.2017 to Jul.2019.The levels of serum DBP,Klotho,and 25-hydroxyvitamin D₃[25?OH?D₃]were determined and compared between patients and healthy subjects,between winter-spring and summer-autumn,between patients with and without nephrotic syndrome.Their linearity with renal parameters and associations with histological grades of renal tubular injury and clinical factors related to vitamin D deficiency were also assessed.Results:1.The levels of serum 25?OH?D3 in the IMN group were significantly lower than those in the healthy control group.2.The levels of serum DBP in IMN were higher than those in the healthy control group,but there was no statistical difference between them.The levels of serum DBP,but not Klotho and 25?OH?D₃ in IMN during winter were significantly lower than those during summer.There was a significant correlation between serum DBP,Klotho,25?OH?D3,and Uric acid in IMN patients.There was also a significant correlation between serum DBP,not Klotho,25?OH?D3,and urinary alpha-1-microglobulin/urine creatinine?A1M/UCr?in IMN patients.4.There was no statistical difference between patients with and without nephrotic syndrome,among serum DBP,Klotho,and 25?OH?D₃.5.There was no obvious difference between the two groups of estimated glomerular filtration rate?eGFR?,among the three factors above.6.The level of serum Cystatin-C?Cys-C?is higher and the level of eGFR is lower in the patients with grade II of histological tubular injury than the other groups.However,There was no statistical difference in three groups,among serum DBP,Klotho,and25?OH?D3.7.No significant differences in clinical factors,including disease course,history of smoking and hypertension,systolic blood pressure?SBP?,diastolic blood pressure?DBP?were observed between patients with and without vitamin D deficiency.Conclusion:In the patients with idiopathic membranous nephropathy,the level of25?OH?D3 is significantly lower than that of the healthy control group,but there is no significant seasonal difference.The level of DBP is higher in IMN group than in the healthy group,but there is no statistical difference.The levels of DBP and Klotho are not significantly correlated with 25?OH?D3,nor with major renal function indicators.The level of DBP in serum is related to urinary A1M/UCr,indicating that it was related to renal tubular injury in the patients with IMN.