Single-sample methods to measure GFR with technetium-99m-DTPA.
Many single-sample methods have been suggested to simplify the methodology of glomerular filtration rate (GFR) measurement. The relative accuracy of these competing methods is still not clear for clinical practice.


METHODS
Fifty-four GFR studies with 99mTc-DTPA were performed on 37 adult patients (serum creatinine 0.8-10 mg/dl). Each study included a UV/P, plasma clearance method (three-sample) and single-sample methods. The single-sample methods used were those of Christensen and Groth (modified by Watson), Constable, Dakubu, Groth and Aasted, Jacobsson, Morgan, Russell and Tauxe.


RESULTS
When the GFR > or = 30 ml/min (n = 26), all of the single-sample methods were highly correlated with UV/P. The correlation of the single-sample method with the plasma clearance was higher than with UV/P. In this group (GFR > or = 30 ml/min), the Groth 4-hr sample method had the best value of both absolute difference and percent absolute difference (mean +/- s.e. = 11.05 +/- 2.51 ml/min and 14.08% +/- 2.43%, respectively). Most single-sample methods do not perform well at GFR < 30 ml/min (n = 28), and none of them has a good correlation with UV/P or plasma clearance at this level of renal function. However, the Groth and Aasted's 4-hr sample method was the best compared with others (mean +/- s.e. = 8.43 +/- 1.30 ml/min for absolute difference, and 65.91% +/- 16.70% for percent absolute difference).


CONCLUSIONS
Single-sample methods may not correctly predict GFR in advanced renal failure. Groth and Aasted's method with 4-hr plasma sample has both the lowest mean absolute difference and percent absolute difference in both the group with GFR > or = 30 ml/min and GFR < 30 ml/min. All methods perform acceptably at GFR > or = 30 ml/min.
Li
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Department of Nuclear Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York, USA.
Lee
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HB
Blaufox
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MD
D000328:Adult; D000368:Aged; D003404:Creatinine; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D016284:Technetium Tc 99m Pentetate; D013997:Time Factors
D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate