Kidney Week

Abstract: SA-PO1008

Impaired Secretory Clearance in the Residual Kidney of Hemodialysis Patients

Session Information

• Hemodialysis and Frequent Dialysis - V
  November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Dialysis

• 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

• Bolanos, Christian G., Stanford University, Palo Alto, California, United States

Christian G. Bolanos,

• Leong, Sheldon, Stanford University, Palo Alto, California, United States

Sheldon Leong,

• Plummer, Natalie, Stanford University, Palo Alto, California, United States

Natalie Plummer,

• Meyer, Timothy W., Stanford University, Palo Alto, California, United States

Timothy W. Meyer,

• Sirich, Tammy L., Stanford University, Palo Alto, California, United States

Tammy L. Sirich,

Background

Residual kidney function is associated with survival and better control of fluid and inorganic solutes in patients on hemodialysis (HD). This study assessed the extent to which the residual kidney maintains the ability to clear organic solutes by tubular secretion.

Methods

Plasma and timed urine were collected to measure kidney clearances for the secreted solutes hippurate (HIPP), indoxyl sulfate (IS), and p-cresol sulfate (PCS) in 10 patients on twice weekly HD with residual kidney function and in 10 control subjects. Clearances were expressed in terms of the free, unbound solute levels. Clearances were normalized to the GFR (fractional clearances) to assess the degree to which solutes were secreted. GFR was calculated as the mean of the creatinine and urea kidney clearances.

Results

As expected, the GFR was much lower in the HD patients than control subjects (4.0±2.0 vs. 97±18 ml/min/1.73m², p<0.001). Kidney clearances of HIPP, IS, and PCS were also much lower in the HD patients. The fractional clearances of these solutes remained greater than 1 in the HD patients, confirming that they were cleared by secretion.

The degrees to which secretory clearances of these solutes were maintained relative to GFR in the residual kidney, however, varied greatly. Fractional HIPP clearance was preserved in the HD patients as compared to control subjects (15±10 vs. 19±5, p 0.35). Secretion of IS and PCS, however, declined to a greater degree than the GFR in the residual kidney of HD patients, so that their fractional clearances were markedly lower than the control subjects (IS: 9.2±6.1 vs. 31±18, p<0.001; PCS: 4.4±2.7 vs. 12±3, p<0.001).

Conclusion

Secretory clearances of organic solutes are variably impaired in the residual kidney of HD patients. Residual secretory function cannot therefore be assessed by measurement of a single solute. Further studies will be required to assess the residual kidney’s contribution to removal of medications and uremic solutes which are cleared by secretion and guide adjustment of medication doses and dialysis prescriptions.

* p < 0.001, HD versus Control

Funding

• Veterans Affairs Support