Kidney Week

Abstract: TH-OR70

Tubular Secretion of Creatinine and Clinical Outcomes: The AASK Trial

Session Information

• Preventing Progression and Reassessing Race in GFR Estimation
  November 04, 2021 | Location: Simulive, Virtual Only
  Abstract Time: 04:30 PM - 06:00 PM

Category: CKD (Non-Dialysis)

• 2101 CKD (Non-Dialysis): Epidemiology, Risk Factors, and Prevention

Authors

• Garimella, Pranav S., University of California San Diego, La Jolla, California, United States

Pranav S. Garimella, MD, FASN, MPH

• Cummins, Kevin M., California State University Fullerton, Fullerton, California, United States

Kevin M. Cummins,

• Gassman, Jennifer J., Cleveland Clinic, Cleveland, Ohio, United States

Jennifer J. Gassman,

• Gabbai, Francis B., University of California San Diego, La Jolla, California, United States

Francis B. Gabbai,

• Ix, Joachim H., University of California San Diego, La Jolla, California, United States

Joachim H. Ix,

Background

Tubular secretion is a critical kidney function that is not routinely assessed. We evaluated the association of tubular secretion of creatinine calculated using the difference between either measured glomerular filtration rate (mGFR) or estimated GFR (eGFR) and 24-hour urine creatinine clearance (CrCl) with long-term clinical outcomes.

Methods

This prospective analysis of the African American Study of Kidney Disease (AASK) included 999 participants with baseline measures of iothalamate mGFR, creatinine based eGFR and 24-hour urine CrCl. Tubular secretion of creatinine was calculated in two ways as the difference between 1) CrCl and mGFR (mTS_cr); and 2) CrCl and eGFR (eTS_cr). The associations between mTS_cr and eTS_cr with incident end-stage kidney disease (ESKD) and cardiovascular disease (CVD) and all-cause mortality were evaluated using Cox regression.

Results

At baseline, the mean mGFR was 45.3 ml/min/1.73 m², and the mean CrCl was 49.3 ml/min/1.73 m². The mean (SD) mTS_cr and eTS_cr were 4.0 (14) and 6.5 (14) ml/min/1.73/m² respectively. Over 4.2 years of follow up there were 149 ESKD, 82 all-cause mortality, and 132 incident CVD events. Each 10 ml higher mTS_cr (HR 0.73, 95% CI 0.58-0.93) and each 10 ml higher eTS_cr (HR 0.59, 95% CI 0.44, 0.79) were associated with lower risk of ESKD, after adjustment for mGFR or eGFR, proteinuria, and other potential confounding factors (Table). Associations between mTS_cr or eTS_cr with lower risk of all-cause mortality or CVD events were not detected.

Conclusion

eTScr provides a measure of creatinine secretion similar to mTScr and is strongly associated with risk of ESKD, independent of GFR, proteinuria, or other risk factors. This allows for the incorporation of eTScr into epidemiological studies which may not have collected mGFR.

Funding

• NIDDK Support