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HelpTest Code CGAK Chromogranin A, Serum
Reporting Name
Chromogranin A, SUseful For
Aiding in monitoring disease progression during the course of disease and treatment in patients with gastroenteropancreatic neuroendocrine tumors (grade 1 and grade 2) when used in conjunction with other clinical methods
This test is not indicated for use as a stand-alone monitoring assay.
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Patient Preparation: For at least 2 weeks before specimen collection, patient should stop taking proton pump inhibitor medications.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Information: Centrifuge and aliquot serum into plastic vial. Do not submit in original tube.
Specimen Minimum Volume
0.2 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Frozen (preferred) | 90 days | |
| Ambient | 48 hours | ||
| Refrigerated | 48 hours |
Reference Values
<93 ng/mL
Reference values apply to all ages.
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
86316
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CGAK | Chromogranin A, S | 9811-1 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| CGAK | Chromogranin A, S | 9811-1 |
Method Description
Chromogranin A (CgA) is measured in a homogeneous automated immunofluorescent assay. This assay uses technology based on a variant of Forster resonance energy transfer, called time-resolved amplified cryptate emission (TRACE). A mouse monoclonal antibody against CgA is labeled with europium cryptate (TRACE donor) and a second mouse monoclonal antibody against CgA is labeled with Alexa Fluor 647 (TRACE acceptor). CgA is sandwiched between the 2 antibodies, bringing them into close proximity. When the antigen-antibody complex is excited with a nitrogen laser at 337 nm, some fluorescent energy is emitted at 620 nm, and the rest is transferred by nonradiative dipole-dipole coupling to Alexa Fluor 647. This energy is then emitted as fluorescence at 647 nm. A ratio of the energy emitted at 647 nm to that emitted at 620 nm (internal reference) is calculated for each sample. Signal intensity is proportional to the number of antigen-antibody complexes formed and, therefore, to antigen concentration.(Package insert: B R A H M S CgAII KRYPTOR Instruction for Use. Thermo Fisher Scientific Inc; V1.1us, 09/2023)
Report Available
1 to 3 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Day(s) Performed
Monday through Saturday
Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-General Request (T239)
-Oncology Test Request (T729)
Secondary ID
34641Method Name
Immunofluorescent Assay (IFA)