title: Basal and stimulated calcitonin and procalcitonin by various assays in patients with and without medullary thyroid cancer.
abstract: BACKGROUND
  Calcitonin (CT) is a sensitive marker for evaluation of medullary thyroid cancer (MTC). However, CT measurement can vary with assay- and nonassay-dependent factors, and procalcitonin (PCT) measurement has been proposed for evaluating questionable increases in CT.
  
  
  METHODS
  We tested 2 fully automated CT assays (Immulite [IL] and Liaison [LIA]) and 1 nonautomated CT assay (IRMA, Medipan) and compared these results with PCT (Brahms Kryptor). We evaluated preanalytical conditions and PCT cross-reactivity in sera of 437 patients with clinical conditions associated with hypercalcitoninemia. Additionally, we determined the true "nil" CT concentration in 60 thyroidectomized patients and defined CT cutoff concentrations for pentagastrin stimulation testing in 13 chronic kidney disease (CKD) patients and 10 MTC patients.
  
  
  RESULTS
  Markedly decreased CT concentrations were found after storage of sera for >2 h at room temperature and >6 h at 4 °C. Cutoff concentrations for basal and stimulated CT were disease and assay dependent. Proton pump inhibitor therapy was the most frequent reason for increased CT. PCT concentrations were higher in patients with MTC than in patients with CKD without infections (P<0.001). Whereas IL and LIA demonstrated comparable analytical quality, the IRMA gave increased CT concentrations in nil sera and showed cross-reactivity with PCT in patients with concomitant bacterial infection.
  
  
  CONCLUSIONS
  IL, LIA, and IRMA detected increased CT concentrations in non-MTC patients and discriminated MTC from CKD patients in pentagastrin tests. PCT assessment may be helpful in the diagnostic work-up of increased CT concentrations in questionable clinical circumstances.
authors.affiliation: Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, Department of Internal Medicine, Neurology and Dermatology, Clinic for Endocrinology and Nephrology, University of Leipzig, Leipzig, Germany. juergen.kratzsch@medizin.uni-leipzig.de
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kratzsch
authors.forename: Anne
authors.initials: A
authors.lastname: Petzold
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Raue
authors.forename: Walter
authors.initials: W
authors.lastname: Reinhardt
authors.forename: Martina
authors.initials: M
authors.lastname: Bröcker-Preuss
authors.forename: Rainer
authors.initials: R
authors.lastname: Görges
authors.forename: Klaus
authors.initials: K
authors.lastname: Mann
authors.forename: Wolfram
authors.initials: W
authors.lastname: Karges
authors.forename: Nils
authors.initials: N
authors.lastname: Morgenthaler
authors.forename: Markus
authors.initials: M
authors.lastname: Luster
authors.forename: Christoph
authors.initials: C
authors.lastname: Reiners
authors.forename: Joachim
authors.initials: J
authors.lastname: Thiery
authors.forename: Henning
authors.initials: H
authors.lastname: Dralle
authors.forename: Dagmar
authors.initials: D
authors.lastname: Fuhrer
mesh_terms: D001331:Automation; D014408:Biomarkers, Tumor / Q000097:blood*; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D002138:Calibration; D018276:Carcinoma, Medullary / Q000097:blood / Q000175:diagnosis*; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D010418:Pentagastrin; D011498:Protein Precursors / Q000097:blood*; D055550:Protein Stability; D012015:Reference Standards; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D013964:Thyroid Neoplasms / Q000097:blood / Q000175:diagnosis*; D013965:Thyroidectomy
chemical_list: D014408:Biomarkers, Tumor; C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D010418:Pentagastrin; D015740:Calcitonin Gene-Related Peptide