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Kidney Week

Abstract: PO1498

A New Insight into Hyperchloremic Metabolic Acidosis in Kidney Transplant Recipients: Increased Postglomerular Blood Flow Is a Key Condition for Calcineurin Inhibitor-Induced Renal Tubular Acidosis

Session Information

Category: Fluid, Electrolyte, and Acid-Base Disorders

  • 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

  • Kaneko, Shuzo, Tsukuba Daigaku Igaku Iryokei, Tsukuba, Ibaraki, Japan
  • Usui, Joichi, Tsukuba Daigaku Igaku Iryokei, Tsukuba, Ibaraki, Japan
  • Takahashi, Kazuhiro, Tsukuba Daigaku Igaku Iryokei, Tsukuba, Ibaraki, Japan
  • Kimura, Tomokazu, Tsukuba Daigaku Igaku Iryokei, Tsukuba, Ibaraki, Japan
  • Hoshi, Akio, Tsukuba Daigaku Igaku Iryokei, Tsukuba, Ibaraki, Japan
  • Yamagata, Kunihiro, Tsukuba Daigaku Igaku Iryokei, Tsukuba, Ibaraki, Japan
Background

Hyperchloremic metabolic acidosis (HCMA) due to renal tubular acidosis(RTA) is a common in kidney transplant recipients(KTR). Calcineurin inhibitor (CNI) have been identified as a cause but have not been fully proven, and whether HCMA is a determinant of poor graft prognosis is controversial.

Methods

HCMA was defined as having a Na-CL (simple strong ion difference) value of 34 or less. All the cases of having diarrhea were excluded. The study group consisted of 26 KTRs who received the renal hemodynamic studies based on urinary clearance of inulin and para-aminohippuric acid 1year post-KT. And glomerular filtration rate (GFR), renal plasma flow (RPF), filtration fraction(FF) (GFR/RPF) and pre-/post-glomerular vascular resistance (pre-/postVR) were calculated.

Results

The incidence of HCMA was 31%(8/26). The univariate analysis of HCMA compared with non-HCMA significantly showed an increase in RPF(P=0.016), a decrease in post-VR(P=0.003), and a decrease in FF(P=0.0001), suggesting an increase in post-glomerular peritubular blood flow. In addition, the aah lesion score, an indicator of CNI vasculopathy, was significantly higher in the HCMA(P=0.015). All cases with HCMA were classified into low post-VR (Fig.1). Furthermore, in low post-VR alone, the tacrolimus trough level was significantly higher in the HCMA(P=0.002) (Fig.2).

Conclusion

In KTRs, increased postglomerular peritubular blood flow is a key condition for CNI-induced RTA. The presence of HCMA is probably not a serious condition, but rather a desirable hemodynamic state, however, more attention should be paid not to elevate CNI concentration levels in such condition.