Underestimation of impaired kidney function with serum creatinine

Area of Science:

• Nephrology
• Clinical Chemistry
• Diagnostic Medicine

Background:

• Serum creatinine (SCr) is a common biomarker for assessing kidney function.
• Normal SCr levels can mask significantly reduced glomerular filtration rate (GFR).
• Early detection of renal dysfunction is critical for timely intervention.

Purpose of the Study:

• To quantify the misclassification rate of patients with reduced GFR but normal SCr.
• To evaluate the effectiveness of the reexpressed four-variable Modification of Diet in Renal Disease (MDRD) equation for GFR estimation.
• To highlight the limitations of relying solely on SCr for diagnosing kidney impairment.

Main Methods:

• Analysis of 928 patients' serum creatinine measurements.
• Calculation of estimated GFR (eGFR) using the reexpressed four-variable MDRD study equation.
• Comparison of eGFR results with SCr levels to identify discrepancies.

Main Results:

• 29.1% of patients had renal dysfunction based on eGFR (<60 ml/min/1.73 m²).
• Only 17.5% showed abnormal renal function based on SCr (>1.5 mg/dl).
• SCr misclassified 11.6% of patients with impaired kidney function, with higher rates in females (15%) than males (9%).

Conclusions:

• Relying solely on normal SCr can lead to underdiagnosis of renal impairment.
• The reexpressed four-variable MDRD equation aids in early identification of kidney dysfunction.
• Integrating eGFR calculations is essential for comprehensive renal function assessment.