Endocrine Abstracts

Introduction: Chromogranin A (CgA) is a main, nonspecific marker of neuroendocrine tumours (NET). There are various commercially assays for the measurement of CgA concentration in serum or plasma. These assays differ in analytical techniques (RIA, ELISA, CLIA), have different standardization, and use different antibodies which recognize different epitopes of CgA molecule.

Aim of study: Our study was designed to confirm the noted earlier differences in CgA levels measured in serum and plasma, and to establish respective references ranges in a group of healthy males.

Material and methods: 145 male blood donors (age mean±S.D. 35.7±9.4; range 19–61 years). At each collection, blood was withdrawn into two tubes: one in EDTA2K (plasma) and one with clot activator (serum). Chromogranin A was measured by immunoradiometric kit (CIS bio, France).

Results: In blood donors, the median (and the range) of CgA concentration determined in serum samples was 42.0 ng/ml (16–108 ng/ml) and in plasma samples was 58.0 ng/ml (23–153 ng/ml). The differences between serum and plasma ranged 15–79% (median 26%). Plasma CgA levels were significantly higher in relation to serum CgA levels (P<0.0001). Correlation of CgA in serum and plasma was r=0.9099; r²=0.8493; P<0.01. The determined reference ranges for CgA measured in serum and plasma in males were: 21.0–108.0 and 31.0–153.0 ng/ml respectively.

Conclusions: Significant differences in the concentrations of CgA measured in plasma and in serum demand application of separate reference ranges adjusted to the sort of the investigated material.