A new quantitative method for estimating glomerular filtration rate and its clinical value.

BACKGROUND AND AIM

The estimation of the glomerular filtration rate (GFR) is essential for the renal function. However, all estimation methods for GFR have advantages and disadvantages. The aim of this study was to develop a new quantitative method for estimating GFR and evaluate its clinical value.

METHODS

The new GFR was estimated by quantifying the accumulation of Tc-99m DTPA in the dual kidneys and bladder during a gamma camera renogram study in 116 patients with chronic kidney disease. GFR was determined by this new method (nGFR), Gates' gamma camera technique (gGFR), a two-plasma sampling method (tGFR) and creatinine-based clearance as estimated by Cockcroft-Gault (cGFR) and abbreviated MDRD (aGFR) formulae. The correlation analysis, Bland-Altman analysis and receiver-operating characteristic (ROC) plots were carried out among above methods.

RESULTS

The nGFR value has significant correlation with tGRF (r = 0·827, P<0·01). The nGFR had the best overall performances with a lowest bias deviation (3·1 ml min(-1) /1·73 m(2) ), better precision (53·0 ml min(-1) /1·73 m(2) ), narrowest interquartile range (13·5 ml min(-1) /1·73 m(2) ) and best accuracy (68·1%) within 30% of the tGFR, compared with those of gGFR, cGFR and aGFR. The new method had the similar maximum accuracy with the Gates' method and creatinine clearance as estimated by Cockcroft-Gault and abbreviated modification of diet in renal disease (MDRD) method. The new method had better repeatability characteristic compared with the Gates' method.

CONCLUSIONS

The new method for estimating GFR had the better performances compared with the Gates' method and creatinine clearance as estimated by Cockcroft-Gault and MDRD method.