In 2014, two external quality assessment trials were performed on 13 test items grouped in four categories. The laboratories procured the materials for the first and second trials on 13 May 2014 and 11 November 2014, respectively. The trials were performed on 13 test items, including tumour markers, thyroid hormones, cardiac marker troponin (troponin T or troponin I), and procalcitonin as a new biomarker for immunoassay methods. The bone marker carboxy-terminal collagen crosslinks (CTX) has been replaced by procalcitonin this year because only a limited number of institutions used it. External quality surveys of the 13 immunoassay test items with 8 control materials were performed as scheduled. The 13 control materials included six tumour markers, alpha-fetoprotein, carcinoembryonic antigen, carcinoma antigen 125, carbohydrate antigen 19-9, human chorionic gonadotrophin, and prostate specific antigen, as well as five thyroid markers, thyroid hormone 3 (T3), T4, thyroid stimulating hormone, free T4, and thyroglobulin. This year, procalcitonin has been introduced as a new biomarker in addition to troponin, which was introduced last year. Five homemade pooled sera and three commercial control sera were used as survey materials. The MAS Tri-point Liquimmune level 3 (Medical Analysis Systems Inc., USA) was used for controls of thyroid hormones, while Elecsys PreciControl Varia and Elecsys PreciControl Troponin (Roche, Germany) were used for controls of the new biomarkers procalcitonin and troponin, respectively. In the external quality assessment by the Immunoassay Subcommittee, 712 institutions participated in the first trial survey (response rate 97.9%), while 715 participated in the second survey (response rate 97.9%). The quality of the participating laboratories seems to be continuously improving compared to the results of their peers. Additionally, this year procalcitonin has been introduced as a new biomarker instead of the CTX, which was used in 2013, while thyroglobulin and troponin-T/troponin-I, which were used for the 2013 samples, continue to be used in surveys by the Immunoassay Subcommittee.
(J Lab Med Qual Assur 2015;37:190-208)

Keywords: Immunoassay, Quality assurance, External quality assessment, Survey, Tumour marker, Thyroid marker, Cardiac marker, Procalcitonin

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