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Kidney Week

Abstract: TH-OR70

Tubular Secretion of Creatinine and Clinical Outcomes: The AASK Trial

Session Information

Category: CKD (Non-Dialysis)

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


  • Garimella, Pranav S., University of California San Diego, La Jolla, California, United States
  • Cummins, Kevin M., California State University Fullerton, Fullerton, California, United States
  • Gassman, Jennifer J., Cleveland Clinic, Cleveland, Ohio, United States
  • Gabbai, Francis B., University of California San Diego, La Jolla, California, United States
  • Ix, Joachim H., University of California San Diego, La Jolla, California, United States

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.


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 (mTScr); and 2) CrCl and eGFR (eTScr). The associations between mTScr and eTScr with incident end-stage kidney disease (ESKD) and cardiovascular disease (CVD) and all-cause mortality were evaluated using Cox regression.


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) mTScr and eTScr 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 mTScr (HR 0.73, 95% CI 0.58-0.93) and each 10 ml higher eTScr (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 mTScr or eTScr with lower risk of all-cause mortality or CVD events were not detected.


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.


  • NIDDK Support