Background: Tumor M2-PK (Tu M2-PK) as the inactive dimeric form of pyruvate kinase M2 has been proven to be elevated in breast, lung, renal and gastrointestinal malignancies. We compared this marker in 26 patients with metastatic thyroid carcinoma using the established tumor marker thyroglobulin (Tg).
Materials and methods: Plasma Tu M2-PK was measured using an ELISA assay (Schebo Biotech, Giessen, Germany) and Tg was measured in serum using an electrochemiluminescence Immunoassay (Tg Elecsys Systems, Roche, Germany), as a part of the routine follow-up of the patients.
Results: At a cut-off of 15 U/ml, Tu M2-PK was elevated in 50% of the patients; at a cut-off of 20 U/ml (grey zone 15-20 U/ml), Tu M2-PK was elevated in 27% of the patients. The correlation coefficient between serum Tg level and Tu M2-PK was -0.093.
Conclusion: Tu M2-PK is less valuable for the detection of malignant thyroid disease than Tg.