Serum Urea Nitrogen, Creatinine, and Estimators of Renal Function

The relationship between mortality rate and renal dysfunction for older adults was the focus of the present study. Linearity comparisons were made between predictors of renal functioning (serum urea nitrogen (SUN) level, creatinine level, Modification of Diet in Renal Disease (MDRD) rate, and Mayo estimated glomerular filtration rate (eGFR) and one-year mortality risk, risk magnitude, and relative importance of predictors. The study sample was comprised of 44,437 hospital patients who had myocardial infarction (MI) and 56,652 patients with heart failure (HF).

Key Findings:

  • One year after discharge, the mortality rate was 33.8 percent for MI patients and 37.7 percent for HF patients.
  • Poorer renal functioning was related to higher mortality risks. SUN level, creatinine level, and eGFR were linearly related to mortality risk.
  • MDRD had a J-shaped relationship with mortality and did not identify mortality risks for patients whose eGFR was normal or near-normal.
  • Out of all of the renal dysfunction predictors, the magnitude of adjusted mortality risk was highest for SUN level and eGFR. SUN level was the most important predictor for HF patients.

Additional study of the role of the Mayo eGFR as a predictor of mortality for older MI or HF patients is recommended.