Diagnostic Use
CA19-9 is not suitable as a cancer screening test.
CA 19-9 can assist in the diagnosis and monitoring of pancreatic cancer. It may be elevated in oesophageal, stomach, biliary tract, colon, breast, thyroid cancers and some ovarian (e.g. mature cystic teratoma) tumours.
Raised CA19-9 can also be found in gastrointestinal tract conditions including pancreatitis, liver diseases, inflammatory bowel diseases and biliary tract obstruction (both malignant or benign causes). It is not possible to reliably distinguish malignant obstructive jaundice from benign causes even when the CA 19-9 level is very high (e.g. >1000 kU/L). A steady or rising CA 19-9 after jaundice resolution could be more suggestive of malignant disease. CA19-9 can also be raised in e.g. interstitial lung or benign thyroid diseases. Heavy black tea consumption had been reported to cause falsely raised CA19-9.
Individuals with Lewis blood group negative phenotype (Le (a-b-)) have falsely low CA19-9 due to defective fucosylation and inability to express CA19-9 antigen.
Due to potential of inter-laboratory and inter-method variation, for serial monitoring purpose recommend testing CA 19-9 by the same laboratory using the same method.
Test Method
Principle: Electrochemiluminescence - Sandwich principle
Analyser: Roche Diagnostics Cobas e801
Reagents: Elecsys CA 19-9
Limitations / Interference
CA19-9 values from NSH laboratory are NOT interchangeable with MMH laboratory (assay methodology is different)