Endocrine Abstracts

Background: Pheochromocytomas (PHEO) and paragangliomas (PGL) are rare neuroendocrine tumors that can lead to life-threatening conditions. The diagnosis of PHEO/PGL is established by measuring normetanephrine and metanephrine. Biochemical detection usually precedes clinical diagnosis of PHEO/PGL by several years. Co-occurrence of cyanotic congenital heart disease (CCHD) and PHEO/PGL has been reported but potential association remains unclear. We aimed to compare plasma metanephrine and normetanephrine between patients with CCHD and patients with acyanotic congenital heart disease (ACCHD).

Material and Methods: We designed cross sectional study of prospective cohort including 44 patients with CHD (13 (29.5%) males, 31 (70.5%) females) of median age 37.5 (31.0-55.6) years at the time of follow up. Thirty-two (73%) patients had CCHD and 12 (27%) patients had ACCHD. Morning blood samples for plasma metanephrine and normetanephrine were collected and measured using the radioimmunoassay. Intra-assay coefficient of variation (CV) was 6–14%, inter-assay CV was 10–15%.

Results: Levels of plasma normetanephrine were significantly increased in patients with CCHD compared to ACCHD (P=0.002); 31.3% (10) patients with CCHD had increased levels of plasma normetanephrine, whereas all ACCHD patients had normal levels. Patients with lower oxygen saturation had significantly higher normetanephrine levels (ρ=-0.444, P=0.003).

Conclusions: Levels of plasma normetanephrine in patients with CCHD are higher than in patients with ACCHD, suggesting that chronic hypoxemia in CCHD contributes to the risk of PHEO/PGL development in this patients population. Routine biochemical screening for PHEO/PGL should be considered in the management of patients with CCHD, to allow timely detection of clinically important PHEO/PGL in this higher risk population. Future research is needed to better understand the association between chronic hypoxia in CCHD and PHEO/PGL.