title: Pretherapeutic estimation of kidney function in patients treated with peptide receptor radionuclide therapy: can renal scintigraphy be safely omitted?
abstract: OBJECTIVE
  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 Tc-mercaptoacetyltriglycine (MAG3) renal scintigraphy with a focus on patients treated with PRRT.
  
  
  METHODS
  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 Tc-MAG3 clearance. In 27 patients, kidney function was assessed before PRRT. Results of blood tests and Tc-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 Tc-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.
  
  
  RESULTS
  In the PRRT subgroup, laboratory test-derived kidney function correlated significantly with Tc-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 Tc-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%).
  
  
  CONCLUSIONS
  Laboratory tests of kidney function correlate significantly with Tc-MAG3 clearance. Because of the moderate accuracy for laboratory tests, Tc-MAG3 clearance is recommended as a standard test to assess kidney function before PRRT.
authors.affiliation: Departments of aNuclear Medicine bInternal Medicine II, University Hospital Würzburg, Würzburg, Germany cInstitute of Psychology, University Innsbruck, Innsbruck, Austria.
authors.forename: Rudolf A
authors.initials: RA
authors.lastname: Werner
authors.forename: Christina
authors.initials: C
authors.lastname: Bluemel
authors.forename: Constantin
authors.initials: C
authors.lastname: Lapa
authors.forename: Dirk O
authors.initials: DO
authors.lastname: Muegge
authors.forename: Theodor
authors.initials: T
authors.lastname: Kudlich
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Buck
authors.forename: Ken
authors.initials: K
authors.lastname: Herrmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000503:physiopathology* / Q000528:radiation effects; D007677:Kidney Function Tests; D007753:Laboratories; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D011878:Radiotherapy / Q000009:adverse effects*; D018000:Receptors, Peptide / Q000378:metabolism*; D012189:Retrospective Studies; D012307:Risk Factors; D012449:Safety; D017263:Technetium Tc 99m Mertiatide; D055815:Young Adult
chemical_list: D018000:Receptors, Peptide; D017263:Technetium Tc 99m Mertiatide