Investigations

• tumour markers ^c

Why?

Raised CEA and serum tissue polypeptide levels make malignancy more likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
pleural effusion c (pre-test probability: 44%)	malignancy (cytology, pleural biopsy specimen or autopsy)	serum CEA > 8.0 mg/dl	5.4 (2.0 to 14)	90%	0.70 (0.60 to 0.82)	55%
		serum tissue polypeptide > 100 U/ml	4.8 (2.8 to 8.3)	89%	0.19 (0.12 to 0.30)	25%