CA 19-9 assay in patients with extrahepatic cholestatic jaundice.

Serum concentrations of the CA 19-9 tumour marker were determined in 35 patients with histologically proven bilio-pancreatic malignancies associated with obstructive jaundice and in 35 patients with benign extrahepatic jaundice due to choledocholithiasis. At a cut-off level of 37 U/ml the sensitivity of this assay was 82.8%, but the specificity was very low (45.7%). Thus CA 19-9 can not be employed to differentiate between malignant and benign extrahepatic jaundice. Serial samples of CA 19-9 were achieved in 7 patients with benign and in 6 patients with malignant biliary obstruction, before and after the disappearance of jaundice. Serum concentrations of this tumour-antigen returned to normal concurrently with the bilirubin values only in patients with benign obstruction, remaining unchanged in all cases of malignancies. The data suggest that patients with extrahepatic jaundice should be evaluated by other examinations or by collecting serial samples for this assay.