Endocrine Abstracts

Objective: To assess the sensitivity of granins – chromogranin A (CgA), secretogranin II (SgII), and secretoneurin (Sn) as biochemical and immunohistochemical markers of non-functioning pituitary adenomas (NFPAs):

Methods: 50 patients with NFPAs were included in the study. Tissue samples were immunostained for pituitary hormones, Ki-67, αSU, CgA, SgII, and Sn. Furthermore, we have determined the levels of CgA, SgII in the serum and Sn in the plasma samples by ELISA method in patients before and after surgical treatment.

Results: Of the 50 NFPA 27 (54%) were gonadotropic tumours, 12 (24%) were null cell adenomas, immunopositivity for ACTH was determined in six cases (12%), for GH in four cases (8%), and for PRL in one case (2%). The median level of Ki-67 was 2.8% (min. 0.2% and max. 7%). We divided all patients in four groups by the degree of granin immunopositivity. High immunopositivity for CgA was found in ten cases (21%), for SgII in 17 (34%), for Sn in 24 (52%) compared to negative staining in 8 (17%), 10 (20%), and 2 (4%) respectively. High immunopositivity for all granin types was more frequent in gonadotropinomas, negative or slow staining for CgA and medium to high staining for SgII and Sn was more typical for ACTH and GH silent adenomas. The average serum CgA concentration before operation was 60.3 nmol/l (±5.2), after surgical treatment 67.84 (±9.8), SgII serum 24.9 (±8.9) and 27.6 (±8.9), plasma Sn 3.2 (±0.2) and 3.4 (±0.3) serum respectively. In healthy subjects the average levels of CgA and Sn were comparable with NFPAs patients 60.2 (±10.5) and 4.1 (±0.7), respectively, but healthy subjects had lower levels of SgII 14.8 (±7.30). We did not found any correlation between granin levels and their tissue expression.

Conclusions: Our work shows that a majority of NFPAs are truly secreting adenomas with significant numbers comprising potentially hazardous cortico- and somatotropinomas. CgA, SgII, and Sn have a high expression in most of the NFPAs, but their serum/plasma levels before and after surgical treatment were not much different from the controls and did not correlate with immunohistochemical results. So serum CgA and plasma SN measurement do not represent a helpful biochemical marker of NFPAs potential hypersecretion, except of SgII, but this requires further study on a large sample of patients.