title: Prediction of clinically relevant hyperkalemia in patients treated with peptide receptor radionuclide therapy.
abstract: BACKGROUND
  Peptide receptor radionuclide therapy (PRRT) is applied in patients with advanced neuroendocrine tumors. Co-infused amino acids (AA) should prevent nephrotoxicity. The aims of this study were to correlate the incidence of AA-induced hyperkalemia (HK) (≥5.0 mmol/l) and to identify predictors of AA-induced severe HK (>6.0).
  
  
  METHODS
  In 38 patients, standard activity of (177)Lu-labelled somatostatin analogs was administered. Pre-therapeutic kidney function was assessed by renal scintigraphy and laboratory tests. For kidney protection, AA was co-infused. Biochemical parameters (potassium, glomerular filtration rate, creatinine, blood urea nitrogen (BUN), sodium, phosphate, chloride, and lactate dehydrogenase (LDH)) were obtained prior to 4 and 24 h after the AA infusion. Incidence of HK (≥5.0) was correlated with pre-therapeutic kidney function and serum parameters. Formulas for the prediction of severe hyperkalemia (>6.0) were computed and prospectively validated.
  
  
  RESULTS
  At 4 h, HK (≥5.0) was present in 94.7% with severe HK (>6.0) in 36.1%. Values normalized after 24 h in 84.2%. Pre-therapeutic kidney function did not correlate with the incidence of severe HK. Increases in K(+) were significantly correlated with decreases in phosphate (r = -0.444, p < 0.005) and increases in BUN (r = 0.313, p = 0.056). A baseline BUN of >28 mg/dl had a sensitivity of 84.6% and a specificity of 60.0% (AUC = 0.75) in predicting severe HK of >6.0 (phosphate, AUC = 0.37). Computing of five standard serum parameters (potassium, BUN, sodium, phosphate, LDH) resulted in a sensitivity of 88.9% and a specificity of 79.3% for the prediction of severe HK >6.0 (accuracy = 81.6%).
  
  
  CONCLUSIONS
  A combination of serum parameters predicted prospectively the occurrence of relevant HK with an accuracy of 81.6% underlining its potential utility for identifying 'high-risk' patients prone to PRRT.
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Lapa
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Rudolf A
authors.initials: RA
authors.lastname: Werner
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Bluemel
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Lueckerath
authors.affiliation: Institute of Psychology, University of Innsbruck, Innsbruck, Austria.
authors.forename: Dirk O
authors.initials: DO
authors.lastname: Muegge
authors.affiliation: Institute of Clinical Chemistry, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Strate
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Heribert
authors.initials: H
authors.lastname: Haenscheid
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schirbel
authors.affiliation: Ahmanson Translational Imaging Division, Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, Los Angeles 90095, CA, USA.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Allen-Auerbach
authors.affiliation: Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Straße 25, Bonn 53127, Germany.
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Bundschuh
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Buck
authors.affiliation: Department of Nuclear Medicine, University Hospital Würzburg, Oberdürrbacher Str. 6, Würzburg 97080, Germany.
authors.forename: Ken
authors.initials: K
authors.lastname: Herrmann
keywords: Amino acids; Hyperkalemia; Kidney function; MAG3; NET; PRRT