Accumulating data indicate that renal uric acid (UA) handling is altered in diabetes and by hypoglycemic agents. In addition, hyperinsulinemia is associated with hyperuricemia and hypouricosuria. However, the underlying mechanisms remain unclear. In this study, we aimed to investigate how diabetes and hypoglycemic agents alter the levels of renal urate transporters. In insulin-depleted diabetic rats with streptozotocin treatment, both UA excretion and fractional excretion of UA were increased, suggesting that tubular handling of UA is altered in this model. In the membrane fraction of the kidney, the expression of urate transporter 1 (URAT1) was significantly decreased, whereas that of ATP-binding cassette subfamily G member 2 (ABCG2) was increased, consistent with the increased renal UA clearance. Administration of insulin to the diabetic rats decreased UA excretion and alleviated UA transporter-level changes, while sodium glucose cotransporter 2 inhibitor (SGLT2i) ipragliflozin did not change renal UA handling in this model. To confirm the contribution of insulin in the regulation of urate transporters, normal rats received insulin and separately, ipragliflozin. Insulin significantly increased URAT1 and decreased ABCG2 levels, resulting in increased UA reabsorption. In contrast, the SGLT2i did not alter URAT1 or ABCG2 levels, although blood glucose levels were similarly reduced. Furthermore, we found that insulin significantly increased endogenous URAT1 levels in the membrane fraction of NRK-52E cells, the kidney epithelial cell line, demonstrating the direct effects of insulin on renal UA transport mechanisms. These results suggest a previously unrecognized mechanism for the anti-uricosuric effects of insulin and provide novel insights into the renal UA handling in the diabetic state.

BackgroundA goal of searching risk factors for chronic kidney disease (CKD) is to halt progressing to end-stage renal disease (ESRD) by potential intervention. To predict the future ESRD, 30% decline in estimated GFR over 2 years was examined in comparison with other time-dependent predictors.MethodsCKD patients who had measurement of serum creatinine at baseline and 2 years were enrolled (n = 701) and followed up to 6 years. Time-dependent parameters were calculated as time-averaged values over 2 years by a trapezoidal rule. Risk factors affecting the incidence of ESRD were investigated by the extended Cox proportional hazard model with baseline dataset and 2-year time-averaged dataset. Predictive significance of 30% decline in estimated GFR over 2 years for ESRD was analyzed.ResultsFor predicting ESRD, baseline estimated GFR and proteinuria were the most influential risk factors either with the baseline dataset or the 2-year time-averaged dataset. Using the 2-year time-averaged dataset, 30% decline in estimated GFR over 2 years by itself showed the highest HR of 31.6 for ESRD whereas addition of baseline estimated GFR, proteinuria, serum albumin and hemoglobin yielded a better model by a multivariate Cox regression model. This novel surrogate was mostly associated with time-averaged proteinuria over 2 years with the cut-off of ~1 g/g creatinine.ConclusionThese results suggest that decline in estimated GFR and proteinuria are the risk factors while serum albumin and hemoglobin are the protective factors by the time-to-event analysis. Future incidence of ESRD is best predicted by 30% decline in eGFR over 2 years that can be modified by intervention to proteinuria, hemoglobin, uric acid, phosphorus, blood pressure and use of renin-angiotensin system inhibitors in the follow-up of 2 years.

A 26-year-old man highly suspected of having antiglomerular basement membrane (GBM) disease was treated with corticosteroid pulse therapy 9 days after initial infection-like symptoms with high procalcitonin value. The patient required hemodialysis the next day of the treatment due to oliguria. In addition to corticosteroid therapy, plasmapheresis was introduced and the patient could discontinue hemodialysis 43 days after the treatment. Kidney biopsy after initiation of hemodialysis confirmed anti-GBM disease with 86.3% crescent formation. Physician should keep in mind that active anti-GBM disease shows even high procalcitonin value in the absence of infection. To pursue recovery of renal function, the challenge of the immediate and persistent treatment with high-dose corticosteroids plus plasmapheresis for highly suspected anti-GBM disease is vitally important despite the presence of reported predictors for dialysis-dependence including oliguria and requiring hemodialysis at presentation.

Percutaneous endovascular angioplasty is a valuable tool to salvage dialysis vascular access failure, but is accident-prone if performed by unskilled operators. We report a case of vascular access failure caused by the plastic protective tube of a balloon catheter, which had been mistakenly left in the vasculature and was undetectable on radiography but was detected by ultrasonography.

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