Clinica Chimica Acta 276 (1998) 19–34 Determination of serum tetranectin: technical and clinical evaluation of three sandwich immunoassays a ,e b c Annemette V. Thougaard , Claus K. Høgdall , Susanne K. Kjær , d e e, * Jan Blaakær , Irakli Jaliashvili , Michael Christiansen a Department of Clinical Studies, Royal Veterinary and Agricultural University, Frederiksberg, Denmark b Department of Obstetrics and Gynecology, Juliane Marie Centret, Rigshospitalet, Copenhagen, Denmark c Danish Cancer Society, Institute of Cancer Epidemiology, Copenhagen, Denmark d Department of Gynecology, Skejby Sygehus, Aarhus, Denmark e Department of Clinical Biochemistry, Statens Serum Institut, Copenhagen, Denmark Received 20 January 1998; received in revised form 21 April 1998; accepted 4 May 1998 Abstract The performance of two sandwich-type immunoassays for the determination of the tumour marker tetranectin using monoclonal antibodies Hyb 130-13 and 130-14 as catching layer was compared with the performance of a polyclonal assay. Sensitivities were 0.4–0.6 mg/l, and intra- and inter-assay coefficients of variation were , 10% in all assays. One-hundred-and-ten blood donors were examined, and women had higher concentrations of tetranectin in serum than men when measured with monoclonal assays (P , 0.05). In preoperative serum samples from 43 patients with ovarian cancer, tetranectin concentrations were reduced ( P , 0.001), and the mean tetranectin concentration decreased with increasing FIGO stage of the patients ( P , 0.05). In sera from patients with ovarian cancer, tetranectin concentrations were lower in the polyclonal assay than in the monoclonal assays. This could, hypothetically, be explained by ligand-binding or other conformational changes in tetranectin, influencing the antigenicity of the molecule.  1998 Elsevier Science B.V. All rights reserved. Keywords: Tumour marker; Method comparison; C-type lectin; Ovarian cancer * Corresponding author. Department of Clinical Biochemistry, Statens Serum Institut, Artillerivej 5, DK- 2300 København S, Denmark. E-mail: mic@ssi.dk 0009-8981 / 98 / $ – see front matter  1998 Elsevier Science B.V. All rights reserved. PII: S0009-8981(98)00092-8