Why do patients with pheochromocytomas/paragangliomas exhibit significantly inconsistent elevation of catecholamines and their metabolites? a large Chinese cohort study.

Abstract

Objectives: Inconsistent elevation of catecholamines (CAs) and metanephrines (MNs) was observed in pheochromocytomas/paragangliomas (PPGLs). This study aimed to explore its potential causes and report the diagnostic efficacy of MNs and CAs in a large Chinese PPGL cohort.

Methods: Clinical data and results of hormone tests were retrospectively collected. The sensitivity of plasma MNs and 24h-urinary CAs was analyzed. Clinical characteristics were compared between patients with positive and negative biochemical results, and among those with inconsistent elevation of MNs and CAs.

Results: Seven hundred and three patients were included, with a median onset age of 41.0 years. Plasma MNs (93% ~ 99%) showed prior diagnostic sensitivity to 24h-urinary CAs (74% ~ 89%). Patients with negative biochemical results presented as a smaller tumor (1.7 cm vs. 4.3 cm, P = 0.001), a higher proportion of normal blood pressure (60.0% vs. 20.5%, P = 0.002) and negative ¹³¹I-meta-iodobenzylguanidine (¹³¹I-MIBG) imaging (55.6% vs. 17.3%, P = 0.012). An earlier age of onset (40.0 vs. 41.0 vs. 44.5 years, P = 0.025), a higher proportion of paroxysmal hypertension (36.5% vs. 29.2% vs. 32.2%, P = 0.005) and the Epinephrine secretion type (79.3% vs. 37.7% vs. 48.0%, P < 0.001) were found in patients with the ratio of MNs/CAs elevation multiples <0.5 than those with the ratio between 0.5 and 2 or >2.

Conclusions: Plasma MNs exhibited a superior sensitivity than 24-h-urinary CAs in the Chinese PPGL diagnosis. Patients with a small tumor, normal blood pressure and negative ¹³¹I-MIBG imaging were prone to express negative biochemical levels. Additionally, an obvious elevation of 24-h-urinary CAs than plasma MNs was correlated to paroxysmal hypertension and the Epinephrine type.