Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
Chromogranin A (CgA) is an acidic, hydrophilic protein of 49 kDa present in chromaffin granules of the neuroendocrine cells and is a member of the granin family. Its biological functions have not been completely elucidated, but it is known to be the precursor of several functional peptides including vasostatin, pancreastatin and parastatin. CgA is also released from neuro-endocrine-derived tumours including foregut, midgut and hindgut gastrointestinal NETs, pheochromocytomas, neuroblastomas, medullary thyroid carcinomas, some pituitary tumours, and pancreatic NETs. For this reason, measurement of tissue and circulating CgA is recommended for diagnosis and monitoring of NETs by most of the relevant societies (ENETS, UKINETS, NANETS).
Specimen container paediatric:
Serum – SST
Specimen container adult:
Serum – SST
Minimum volume paediatric:
1 mL blood
Minimum volume adult:
1 mL blood
Special requirements:
Fasting recommended.
Sample stability:
Separated: 3 days at 20 to 25°C, 2 days at 4-8°C
Transport requirements:
Ambient
Interpretation:
Although CgA is used as a marker for neuroendocrine tumours, raised CgA can sometimes be seen in non-neuroendocrine tumours. High levels of CgA may also be found in cases of benign diseases (gastrointestinal disorders, kidney failure, cardiovascular disorders). CgA values may rise during treatment with proton pump inhibitors (PPI). It is recommended to stop PPI treatment for at least two weeks before determination of CgA.
Reference ranges:
<102 µg/L
Factors affecting result:
N.B. Heterophilic antibodies can interfere with immunoassays.
PPI therapy can cause significant elevations in CgA.