[en] Background: As other immunoassays, PTH determination is not free from interferences. Indeed, natural antibodies like heterophile antibodies (HAMA) and rheumatoid factor (RF) can induce falsely elevated results, leading to misdiagnosis and expensive unnecessary explorations. However, in routine practice, these interferences are not always obvious to detect. Methods: On 2084 PTH samples, we applied a validation strategy in four steps to screen for HAMA and rheumatoid factor interferences. Results: 36% of our samples presented an elevated PTH. We found a clinically plausible reason for 91% of them. The remaining 63 suspicious samples were treated with HBT and 40% of them were found to be HAMA positive. RF determination was performed on the HAMA-negative samples and RE was positive in 21 of them. They were then treated with RF-Absorbent. Nine of these 21 samples presented RE interference. Conclusion: Applying this strategy in our routine validation, we managed to avoid spuriously elevated PTH results, which could have caused medical errors as well as unnecessary cost-effective extra-investigations. (c) 2007 Elsevier B.V. All rights reserved.
Disciplines :
Laboratory medicine & medical technology
Author, co-author :
Cavalier, Etienne ; Centre Hospitalier Universitaire de Liège - CHU > Chimie médicale
Carlisi, Agnès
Chapelle, Jean-Paul ; Université de Liège - ULiège > Département de pharmacie > Chimie médicale
Delanaye, Pierre ; Centre Hospitalier Universitaire de Liège - CHU > Néphrologie
Language :
English
Title :
False positive PTH results: An easy strategy to test and detect analytical interferences in routine practice
Lips P. Vitamin D deficiency and secondary hyperparathyroidism in the elderly: consequences for bone loss and fractures and therapeutic implications. Endocr Rev 22 (2001) 477-501
Cavalier E., Delanaye P., Krzesinski J.M., and Chapelle J.P. Comparison of Liaison N-tact PTH (Diasorin) and N-tact PTH SP IRMA (Diasorin) in hemodialyzed patients. Clin Chem Lab Med 43 (2005) 890-891
Kricka L.J. Interferences in immunoassay-still a threat. Clin Chem 46 (2000) 1037-1038
Krahn J., Parry D.M., Leroux M., and Dalton J. High percentage of false positive cardiac troponin I results in patients with rheumatoid factor. Clin Biochem 32 (1999) 477-480
Marks V. False-positive immunoassay results: a multicenter survey of erroneous immunoassay results from assays of 74 analytes in 10 donors from 66 laboratories in seven countries. Clin Chem 48 (2002) 2008-2016
Levey A.S., Bosch J.P., Lewis J.B., Greene T., Rogers N., and Roth D. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of Diet in Renal Disease Study Group. Ann Intern Med 130 (1999) 461-470
Ellis M.J., and Livesey J.H. Techniques for identifying heterophile antibody interference are assay specific: study of seven analytes on two automated immunoassay analyzers. Clin Chem 51 (2005) 639-641
Holmes D.T., Levin A., Forer B., and Rosenberg F. Preanalytical influences on DPC IMMULITE 2000 intact PTH assays of plasma and serum from dialysis patients. Clin Chem 51 (2005) 915-917
Eriksson S., Halenius H., Pulkki K., Hellman J., and Pettersson K. Negative interference in cardiac troponin I immunoassays by circulating troponin autoantibodies. Clin Chem 51 (2005) 839-847
Eriksson S., Junikka M., Laitinen P., Majamaa-Voltti K., Alfthan H., and Pettersson K. Negative interference in cardiac troponin I immunoassays from a frequently occurring serum and plasma component. Clin Chem 49 (2003) 1095-1104
Cole L.A., Rinne K.M., Shahabi S., and Omrani A. False-positive hCG assay results leading to unnecessary surgery and chemotherapy and needless occurrences of diabetes and coma. Clin Chem 45 (1999) 313-314
Butler S.A., and Cole L.A. Falsely elevated human chorionic gonadotropin leading to unnecessary therapy. Obstet Gynecol 99 (2002) 516-517
Levinson S.S., and Miller J.J. Towards a better understanding of heterophile (and the like) antibody interference with modern immunoassays. Clin Chim Acta 325 (2002) 1-15
Lewis J.G., Florkowski C.M., Elder P.A., and Hunt P.J. Rheumatoid factor and false positive sex-hormone binding globulin. Clin Chim Acta 332 (2003) 139-141
Berth M., Bosmans E., Everaert J., et al. Rheumatoid factor interference in the determination of carbohydrate antigen 19-9 (CA 19-9). Clin Chem Lab Med 44 (2006) 1137-1139
Onuska K.D., and Hill S.A. Effect of rheumatoid factor on cardiac troponin I measurement using two commercial measurement systems. Clin Chem 46 (2000) 307-308
Souberbielle J.C., Boutten A., Carlier M.C., et al. Inter-method variability in PTH measurement: implication for the care of CKD patients. Kidney Int 70 (2006) 345-350
