Glomerular filtration rate measurement: a neglected test in urological practice

Area of Science:

• Nephrology
• Nuclear Medicine
• Clinical Chemistry

Background:

• Accurate measurement of glomerular filtration rate (GFR) is crucial for clinical practice and renal function monitoring.
• Existing methods for GFR assessment vary in accuracy and reproducibility.

Purpose of the Study:

• To evaluate the accuracy and reproducibility of different GFR measurement techniques in a clinical setting.
• To compare 99mTc-DTPA clearance, 24-hour creatinine clearance, and estimated creatinine clearance against a reference method.

Main Methods:

• Simultaneous clearance measurements of iohexol (reference), 99mTc-DTPA, 24-hour renal creatinine, and estimated creatinine were performed in 31 patients.
• Reproducibility was assessed through repeat measurements for each method.

Main Results:

• 99mTc-DTPA clearance demonstrated high accuracy (mean difference 0.2 mL/min) and reproducibility (5.4%) compared to the reference method.
• 24-hour creatinine clearance showed significant inaccuracy (mean difference 21.6 mL/min) and poor reproducibility (24.3%).
• Estimated creatinine clearance offered better accuracy (mean difference 0.6 mL/min) and reproducibility (6.1%) than 24-hour creatinine clearance.

Conclusions:

• Single-injection 99mTc-DTPA clearance is an accurate and reproducible method for GFR assessment and renal function monitoring.
• 24-hour creatinine clearance is not sufficiently accurate or reproducible for clinical use.
• Estimated creatinine clearance from a single serum sample is a viable alternative to the traditional 24-hour urine collection method.