Single-sample 99mTc-diethylenetriamine penta-acetate plasma clearance in advanced renal failure by the mean sojourn time approach.
OBJECTIVE
The single-sample Tc-diethylenetriamine penta-acetate (DTPA) clearance method by Christensen and Groth is recommended by the Radionuclides in Nephrourology Committee on Renal Clearance for use in adults with an estimated glomerular filtration rate (GFR) > or = 30 ml/min. The purpose of this study was to test a new Tc-DTPA single-sample low clearance formula for GFR lesser than 30 ml/min.


METHODS
Twenty-one adult patients (29 investigations) were included. Reference clearance was calculated with both Cr-EDTA and Tc-DTPA according to Brøchner-Mortensen with samples drawn between 3 and 24 h. Single-sample clearance was calculated from a 24 h sample using the low clearance formula(Equation is included in full-text article.) C(t) is the activity of the tracer in the plasma sample t minutes after the injection and Q0 is the injected amount. ECV is the extracellular volume in ml defined as the distribution volume of the tracer. ECV is estimated from the body surface area as ECV=8116.6xbody surface area-28.2.


RESULTS
The mean difference between reference and Tc-DTPA single-sample clearance was -0.5 ml/min (SD 1.0 ml/min) for Tc-DTPA and -0.8 ml/min (SD 1.2 ml/min) for Cr-EDTA as reference clearance.


CONCLUSIONS
In adult patients it is possible, even with GFR lesser than 30 ml/min, to get an accurate determination of Tc-DTPA plasma clearance from a single sample using the mean sojourn time approach. The blood sample should be obtained about 24 h after injection of the GFR tracer.
Gref
Margareta C
MC
Department of Clinical Physiology, Institution of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden. Margareta.Gref@vll.se
Karp
Kjell H
KH
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D012015:Reference Standards; D012189:Retrospective Studies; D016284:Technetium Tc 99m Pentetate / Q000097:blood* / Q000493:pharmacokinetics*; D013997:Time Factors
D016284:Technetium Tc 99m Pentetate