TKT and Pleural effusion: A meta‐analysis including 49 studies suggested that the pooled sensitivity and specificity of pleural effusion CEA for diagnosing MPE were 0.549 and 0.962.14 In a previous study,18 the diagnostic value of TK, neuron‐specific enolase (NSE), CEA, and cytokeratin fragment 19 (CYFRA 21‐1) was determined, and the TK concentration was investigated using a radio enzyme assay.