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Test Code Chromogranin A Chromogranin A, Serum

Reporting Name

Chromogranin A, S

Useful For

Follow-up or surveillance of patients with known or treated carcinoid tumors

 

An adjunct in the diagnosis of carcinoid tumors

 

An adjunct in the diagnosis of other neuroendocrine tumors, including pheochromocytomas, medullary thyroid carcinomas, functioning and nonfunctioning islet cell and gastrointestinal amine precursor uptake and decarboxylation tumors, and pituitary adenomas

 

A possible adjunct in outcome prediction and follow-up in advanced prostate cancer


Specimen Required


Patient Preparation: Proton pump inhibitor drugs should be discontinued for at least 2 weeks before collection.

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic screw-top aliquot tube

Specimen Volume: 0.5 mL

Collection Information: Spin down and remove serum from clot. Do not submit in original tube.


Specimen Type

Serum

Specimen Minimum Volume

0.2 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Frozen 365 days

Day(s) and Time(s) Performed

Monday through Friday; 2:30 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Immunofluorescent Assay

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 XL665 (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 XL665. This energy is then emitted as fluorescence at 665 nm. A ratio of the energy emitted at 665 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intensity is proportional to the number of antigen-antibody complexes formed, and therefore to antigen concentration.(Unpublished Mayo method)

Reference Values

<93 ng/mL

Reference values apply to all ages.

Test Classification

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

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

Forms

If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

General Request Form (T239) (http://www.mayomedicallaboratories.com/it-mmfiles/general-request-form.pdf)

Oncology Test Request Form (T729) (http://www.mayomedicallaboratories.com/it-mmfiles/oncology-request-form.pdf)

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

Original collection tube: serum not poured off into an aliquot tube