CA 19-9 - Tumour Marker
Investigation : CA 19-9 - Tumour Marker
Specimen type : Serum
Spec container : Serum Gel 
Volume required : 5 ml
Reference range : <35 KU/l
Turnaround : <48 hours

Carbohydrate antigen (CA) 19-9

Reference range: <35KU/l

Additional information on CA19-9 and its clinical use can be found here: CA19-9.

CA 19-9 is a high molecular weight glycoprotein. The 3 - 7% of the population who have the Lewis a-negative/b-negative blood group do not synthesize CA 19-9.

Malignancies with elevated CA 19-9
Pancreatic carcinoma, cholangiocarcinoma, gastric carcinoma and colorectal carcinoma.

Benign conditions associated with elevated CA 19-9
Acute and chronic pancreatitis, hepatocellular jaundice, cirrhosis, acute cholangitis, cystic fibrosis. Ca 19-9 can be >5,000 KU/L in cholangitis.

CA 19-9 is neither sufficiently specific nor sensitive enough to be used in screening for early pancreatic carcinoma in asymptomatic individuals.

Main clinical applications:

  1. Useful in the diagnosis of pancreatic carcinoma in patients with pancreatic masses. Levels can be high (hundreds) in the context of jaundice or ascites and this marker should not used routinely in patients with these conditions unless a pancreatic mass is seen on imaging. Specialist hepatobiliary interpretation may be required.
  2. May be a useful preoperative marker for determining the resectability of a pancreatic carcinoma. The tumour is unlikely to be resectable if the CA 19-9 concentration is greater than 250 KU/l.
  3. Surveillance and monitoring therapy in pancreatic carcinoma. Serial CA 19-9 measurements have a greater sensitivity and specificity than individual measurements for determining response to treatment or predicting progressive disease.
  4. May be a diagnostic aid in cholangiocarcinoma.

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