Endocrine Abstracts

Background: Pheochromocytoma is associated with systemic inflammation, but the underlying mechanisms are unclear. Hypothesising a putative effect of catecholamines on immune cells, we investigated the relationship between plasma metanephrine levels and haematological parameters – as surrogates for systemic inflammation – in patients with pheochromocytoma. Moreover, we aimed to assess the influence of preoperative α-blockade treatment on the inflammation-based scores.

Design and Methods: We included a retrospective cohort of 68 patients with pheochromocytoma who underwent adrenalectomy (mean age 53 years, 64.7% female) and two control groups matched for age, sex and body mass index: 68 patients with non-functioning adrenocortical tumours (NFAT) and 53 with essential hypertension. The full blood count and various inflammation-based scores [neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), lymphocyte/monocyte ratio (LMR), Systemic Inflammation Index (SII), Prognostic-Nutrition Index (PNI)] were assessed in all patients at diagnosis and compared between the three groups. In addition, in a subgroup of pheochromocytomas, these parameters were compared before and after preoperative α-blockade treatment (n=29, median time 110 days, IQR 78.5-261.5) and before and after adrenalectomy (n=26, median time 15.6 months, IQR 5.7-42.3).

Results: A higher inflammatory state, as reflected by both full blood count and inflammation-based scores, was observed in patients with pheochromocytoma compared to NFAT and essential hypertension, whilst no differences were found between the two control groups. Notably, plasma metanephrine levels showed a positive correlation with NLR (r=0.4631), PLR (r=0.3174), SII (r=0.3709), and a negative correlation with LMR (r=0.4368) and PNI (r=0.3741), even after adjustment for age, sex, ethnicity, BMI, and tumor size, except for PLR. After adrenalectomy, we observed a significant increase in lymphocyte count (P=0.01) with corresponding changes in the relative inflammation-based scores. Specifically, a decrease in NLR (P=0.001), PLR (P=0.003), SII (P=0.004) and a concomitant increase in LMR (P=0.0002) were detected postoperatively. Similarly, α-blockade treatment led to a reduction in NLR (P=0.007) and SII (P=0.03).

Conclusions: The preoperative systemic inflammatory state observed in patients with pheochromocytoma, reflected by high NLR, PLR and SII, as well as low LMR and PNI, and ameliorated by adrenalectomy and α-blockade, is probably related to an excessive amount of secreted catecholamines. The impact of circulating catecholamines on the systemic inflammatory response may play a role in the cardio-metabolic comorbidities in patients with pheochromocytoma and may optimise treatment approaches.