A pretherapeutic assessment of kidney function before peptide receptor radionuclide therapy (PRRT) is considered essential because of the potential renal toxicity associated with PRRT. The aim of this study was to investigate the diagnostic performance of laboratory testing and 99mTc-mercaptoacetyltriglycine (MAG3) renal scintigraphy with a focus on patients treated with PRRT.
From January to December 2013 the kidney function of 152 patients was assessed using laboratory tests [creatinine, blood urea nitrogen (BUN), and glomerular filtration rate (GFR)] and 99mTc-MAG3 clearance. In 27 patients, kidney function was assessed before PRRT. Results of blood tests and 99mTc-MAG3 renal scintigraphy, considered the reference standard, were compared in the entire patient cohort (n=152) and in both subgroups (PRRT and non-PRRT) using Student’s t-test. The cutoff values for the laboratory tests for the prediction of abnormal 99mTc-MAG3 clearance were determined by means of receiver operating characteristic analysis. In a further mathematical approach using discriminant analysis, a formula was derived for the prediction of kidney function that included all of the serum parameters.
In the PRRT subgroup, laboratory test-derived kidney function correlated significantly with 99mTc-MAG3 clearance (creatinine: r=−0.429, P=0.037; BUN: r=−0.45, P=0.027; GFR: r=0.44, P=0.022). The correlation was confirmed in the non-PRRT subgroup. The receiver operating characteristic analysis for prediction of abnormal 99mTc-MAG3 clearance resulted in area under the curves of 0.779 for creatinine alone (sensitivity 74.3%, specificity 71.1%; cutoff ≥0.995 mg/dl) and for the combination of creatinine, BUN, and GFR (sensitivity was 74.3% and specificity was 69.3%).
Laboratory tests of kidney function correlate significantly with 99mTc-MAG3 clearance. Because of the moderate accuracy for laboratory tests, 99mTc-MAG3 clearance is recommended as a standard test to assess kidney function before PRRT.
Departments of aNuclear Medicine
bInternal Medicine II, University Hospital Würzburg, Würzburg, Germany
cInstitute of Psychology, University Innsbruck, Innsbruck, Austria
* Rudolf A. Werner and Christina Bluemel contributed equally to the writing of this article.
Correspondence to Christina Bluemel, MD, Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Street 6, 97080 Würzburg, Germany Tel: +49 931 20135983; fax: +49 931 201635000; e-mail: firstname.lastname@example.org
Received July 24, 2014
Accepted July 31, 2014