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ABSTRACTS PRESENTADOS AL 11th INTERNATIONAL SYMPOSIUM "RADIONUCLIDES IN NEPHRO-UROLOGY", REALIZADO EN MONTEREY, CALIFORNIA, 13-17 MAYO 2001.

 

2. DETERMINATION OF GLOMERULAR FILTRATION RATE FROM PLASMA CLEARANCE WITH Tc99m-DTPA BY SINGLE; TWO AND MULTI-SAMPLE METHODS.

Kazuo Itoh, Satoshi Tsushima, Eriko Tsukamoto and Nagara Tamaki,
· Departments of Radiology, Internal Medicine and Nuclear Medicine,
JR Sapporo General Hospital and Hokkaido University School of Medicine, Sapporo,JAPAN.

itohka51@ra2.so-net.ne.jp

 

Background.The plasma sample method following a single injection of radioactive markers has been proved to be simple and accurate for the determination of glomerular filtration rate (GFR) in clinical practice. The aim of this study was to assess clinical accuracy of single-, two-and multi-sample methods.

Patients and Methods. The study was performed on 50 patients with various degrees of renal dysfunction (29 males and 21 females; aged 27-90 years). As a reference the true GFR was determined by means of the two compartment model curve fitting 10 plasma following a single-injection of Tc99m-DTPA. The GFR was estimated by the three methods of single-, two and multi-sample between 75 and 300 min after the injection. The GFR by two and multi-sample methods was determinated with the slope and intercept algorithm and its overestimation was corrected by Brochner-Mortensen's formula.

Results. In all patients with a GFR between 12 and 169 , accuracy for the determination of GFR was identical in both the single-and five-sample methods. In 46 patients with a GFR higher than 30 , the single-sample method exhibited the lowest standard error of mean of difference in GFR. In 38 patients with a GFR lower than 120 , the two and five sample methods were more accurate than the single-sample one. The best combination of sampling time for the two samples was 120 min and 240 min after the injection.

Conclusion. Accuracy of each plasma sample method depends on the preserved GFR. As a matter of practice, the single-sample method is the first choice for a patient who is expected to have a GFR higher than 30 . The two-sample method is indicated only in a patient with severe renal failure with a GFE lower than 30 .