A comparison of glomerular filtration rate values determined using four radionuclide techniques in healthy volunteers

Glomerular filtration rate (GFR) is widely regarded as a reliable method of determining renal function. Very little information is available on normal GFR values, especially on methods using ^99m Tc. The purpose of this study was firstly to obtain GFR values in healthy volunteers to compare three different ^99mTc-DTPA renal clearance methods. Secondly, the ^99mTc-DTPA values were compared to corresponding values obtained from ⁵¹Cr-EDTA renal clearance. Finally a normal range for GFR in the authors´ department was established. Forty healthy volunteers were recruited and divided into two age groups. The first ranged from 18 to 50 years and the second between 51 and 70 years. Four methods of determining GFR were applied simultaneously i.e. (i) a two blood sample method with ⁵¹ Cr-EDTA (used as the reference method), (ii) a single sample imaging and urine collection method, (iii) a single sample imaging and urine quantification method and (iv) a two blood sample method with ^99mTc-DTPA. All GFR values were normalized to body surface area. 95% confidence intervals indicated no significant differences between GFR calculated with the different methods. The distribution of the GFR values for both age groups was done and normal ranges for the different age groups calculated. GFR decreased with age from an average of 85.5 ml/min (18-30 years) to 71.7 ml/min (61-70 years). The GFR values obtained using the four different renal clearance methods showed no significant differences and thus one range of normal values for different age groups is suggested