Renal function--estimation of glomerular filtration rate

Area of Science:

• Nephrology
• Clinical Chemistry
• Pediatric Nephrology

Background:

• Accurate assessment of renal dysfunction is vital for chronic kidney disease (CKD) management.
• Glomerular filtration rate (GFR) is the gold standard for kidney function but is costly to measure directly.
• Serum creatinine is a routine marker, but its sensitivity for early GFR decline is limited.

Purpose of the Study:

• To review methods for estimating GFR using prediction equations for both adults and children.
• To compare the efficacy of creatinine-based versus cystatin C-based equations for GFR estimation.
• To provide guidance for clinical laboratories on reporting estimated GFR (eGFR).

Main Methods:

• Review of prediction equations for estimating GFR.
• Comparison of serum creatinine and serum cystatin C as markers for GFR estimation.
• Evaluation of the Modification of Diet in Renal Disease (MDRD) study equation for adults.
• Assessment of cystatin C-based equations with a prepubertal factor for children.

Main Results:

• The MDRD study equation using serum creatinine provides a suitable GFR estimation in adults.
• Serum cystatin C measurement is proposed as a more sensitive marker for GFR.
• In children under 14 years, cystatin C-based prediction equations with a prepubertal factor appear superior to creatinine-based equations.

Conclusions:

• Clinical laboratories should report estimated GFR (eGFR) using prediction equations alongside serum marker values, as per NKF-K/DOQI guidelines.
• The choice of prediction equation for eGFR estimation should consider patient age, with cystatin C-based equations showing advantages in prepubertal children.
• Accurate eGFR estimation is essential for early detection and effective management of renal dysfunction.