Table 5.

Sources of misclassification for a decline in renal function

Renal Function MethodMeasurement Errora (Decreased Precision)Measurement Bias (Decreased Accuracy)
Measured GFR (iothalamate clearance)+ +0
Estimated GFRb (MDRD or Cockcroft-Gault)++ + +
Reciprocal SCrb (1/SCr)++ + +
Creatinine clearance+ + ++
  • a Physiological variability and assay error.

  • b Systematic changes in creatinine production (muscle mass or protein intake), tubular creatinine secretion, or extrarenal creatinine clearance causes bias, whereas random fluctuations contribute to error.\