Background and aim: Assessment of volume of distribution (VD) and half-life (T1/2) values during glomerular filtration rate (GFR) investigations is a useful quality control check. The aim of this study was to derive reference data for VD and T1/2 and also to provide reference data for GFR from studies performed using 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA).
Methods: This was a retrospective study of 126 healthy potential kidney donors (age range 18–59 years). The GFR was evaluated from 99mTc-DTPA plasma clearance using the 2004 British Nuclear Medicine Society guidelines. The association between VD and body surface area (BSA) was assessed. T1/2 was correlated with age and GFR. The correlation between the Brochner-Mortensen-corrected GFR (BM-GFRCorr) and age was evaluated.
Results: The uncorrected VD value (l) was 10.1×BSA±40.6% (P<0.01). The corrected VD value (l) was 8.19×BSA±34.4% (P<0.01). In individuals under the age of 40 years, the mean T1/2 was 95.0 min±36.2%. In individuals aged 40 years and above, the T1/2 increased at a rate of 0.49 min/year (P=0.04); the T1/2 (min) was 9480×(1/BM-GFRCorr)±35.1% (P<0.01). In individuals younger than 40 years of age, the correlation between BM-GFRCorr and age was not statistically significant (P=0.45), and the mean GFR was 108 ml/min/1.73 m2±27.5%. In individuals aged 40 years and above, the BM-GFRCorr was 170−(1.55×age) ml/min/1.73 m2±36.7% (P<0.001).
Conclusion: Well-defined reference data for VD and T1/2 can be used for quality control checks in GFR investigations. In addition to these, reference data for GFR using 99mTc-DTPA have been defined. This will enhance the interpretation of adult 99mTc-DTPA GFR measurements.