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HelpTEST ID CA19 Carbohydrate Antigen 19-9 (CA 19-9), Serum
Reporting Name
Carbohydrate Ag 19-9, SSpecimen Type
SerumSpecimen Required
Patient Preparation: For 12 hours before specimen collection, patient should not take multivitamins or dietary supplements (eg, hair, skin, and nail supplements) containing biotin (vitamin B7).
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.6 mL
Collection Instructions:
1. Within 2 hours of collection, serum gel tubes should be centrifuged.
2. Within 2 hours of collection, red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Frozen | 90 days | |
| Ambient | 8 hours |
Method Name
Immunoenzymatic Assay
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross Icterus | OK |
Reference Values
<35 U/mL
Day(s) Performed
Monday through Saturday
Report Available
1 to 3 daysSpecimen Retention Time
14 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
86301
Forms
If not ordering electronically, complete, print, and send Oncology Test Request (T729)
Useful For
As a potential adjunct for diagnosis and monitoring of pancreatic cancer
Potentially differentiating patients with cholangiocarcinoma and primary sclerosing cholangitis (PSC) from those with PSC alone
Clinical Information
Carbohydrate antigen 19-9 (CA 19-9) is a modified Lewis(a) blood group antigen. CA 19-9 may be elevated in patients with gastrointestinal malignancies such as cholangiocarcinoma, pancreatic cancer, or colon cancer.
Benign conditions, such as cirrhosis, cholestasis, and pancreatitis, also result in elevated serum CA 19-9 concentrations, but in these cases, values are usually below 1000 U/mL.
Individuals that are Lewis antigen negative (5%-7% of the population) do not express CA 19-9 due to the lack of the enzyme fucosyltransferase needed for CA 19-9 production. In these individuals, a low or undetectable serum CA 19-9 concentration is not informative regarding cancer recurrence.
Cautions
Carbohydrate antigen 19-9 (CA 19-9) is neither specific nor sensitive enough to be used as a cancer screen.
Some individuals do not express CA 19-9. Consequently, low values in these individuals are not informative regarding cancer recurrence.
Serum CA 19-9 levels should not be interpreted as absolute evidence of the presence or absence of malignant disease. Instead, serum CA 19-9 results should be used in conjunction with information from the clinical evaluation of the patient and other diagnostic procedures.
Some patients who have been exposed to animal antigens, either in the environment or as part of treatment or imaging procedures, may have circulating anti-animal antibodies present. These antibodies may interfere with the assay reagents and produce unreliable results.
Method Description
The Access GI Monitor assay is a 2-site immunoenzymatic sandwich assay. A sample is added to a reaction vessel along with paramagnetic particles coated with polyclonal goat-antibiotin antibody, mouse monoclonal-biotin conjugate, and a buffered protein solution. After incubation in a reaction vessel, separation in a magnetic field and washing remove materials not bound to the solid phase. A monoclonal-alkaline phosphatase conjugate is then added. After incubation in a reaction vessel, materials bound to the solid phase are held in a magnetic field, while unbound materials are washed away. The chemiluminescent substrate is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is directly proportional to the concentration of carbohydrate antigen 19-9 in the sample. The amount of analyte in the sample is determined from a stored, multipoint calibration curve.(Package insert: Access GI Monitor. Beckman Coulter; 04/2020)