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PTD - 187

Test Directory -  CA19-9

Please note that for monitoring purposes results from Basildon and Southend are comparable, but results from other laboratories may differ due to methodological differences


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 hepatobilary disease associated with cholestasis.

Request Form

Combined Pathology Blood form (Yellow/Black)


Analysed by referral laboratory if specific criteria met.

Specific Criteria

Monitoring of known pancreatic and gastrointestinal carcinoma.

Patient Preparation

None required



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

Turnaround Time

1 week




2 ml


Yellow top (SST) tube

Causes for Rejection

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.


Critical Difference 52%

CA19-9 levels are elevated in most pancreatitic adenocarcinomas, approx. 50% of gastric carcinomas and approx. 30% of colorectal carcinomas. Levels may also be elevated in benign conditions: acute and chronic pancreatitis, hepatocellular jaundice, cirrhosis, acute cholangitis and cystic fibrosis. Levels should be interpreted with caution and levels between 100 and 200 may be due to cholestasis.

Lab. Handling

Processing: Aliquot (MPA) and store at 4C in separating fridge (CB39). Referral:  CA19 and send or NO199 and save in separating freezer (CB40) at -20C, saved frozen rack.

Version 1.1 / July 2014                                                                                                           Approved by: Consultant Biochemist