Pathology Handbook



Carbohydrate Antigen 19-9

Clinical Indications

CA19-9 is used as a tumour marker in pancreatic, colorectal and biliary tract tumours. Serum CA19-9 is grossly raised in ~80% of stage 2 pancreatic carcinoma (may also be raised in chronic pancreatitis but rarely >60 kU/L).  However, elevated levels are also found in hepatobiliary disease associated with cholestasis (may be >9,000 kU/L).

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Analysed by referral laboratory if specific criteria met.

Specific Criteria

Monitoring of known pancreatic and gastrointestinal carcinoma.

NOTE:  If a patient is having serial tumour marker levels monitored the tests must all be done at the same laboratory as there are significant variations between assays

Turnaround Time

1 week




7 ml


Vacutainer gold top

Lab Handling

Sent to referral laboratory (Charing Cross)

Causes for Rejection

Unlabelled or incorrectly labelled sample; not meeting specific criteria for analysis

Reference Range

Less than 33 kU/L

Half-life in Serum

Approx. 1 day but can vary from less than 1 day to 3 days.


CA19-9 levels are elevated in most pancreatic adenocarcinomas, ~50% of gastric carcinomas and ~30% of colorectal carcinomas. Levels may also be elevated in benign conditions: acute and chronic pancreatitis, hepatocellular jaundice, cirrhosis, acute cholangitis and cystic fibrosis.

CA19-9 is excreted in bile and levels should be interpreted with caution in cholestasis.

Approximately 5% of the population cannot express this antigen (Lewis a-b-) so the test cannot be used to screen for an unknown malignancy