Continuous positive airway pressure therapy reduces the levels of catecholamines and blood pressure in pseudophaeochromocytoma with coexisting obstructive sleep apnoea.

Background: Stress from obstructive sleep apnoea (OSA) stimulates catecholamine release and consequently can exacerbate hypertension, even in the absence of a catecholamine-producing tumour (phaeochromocytoma). As such, a positive screening test for suspected phaeochromocytoma may be misleading. There exists only a handful case reports, and no controlled trials, how continuous positive airway pressure (CPAP) to treat OSA influences catecholamine levels. We examined changes to levels of urinary catecholamine and blood pressure in response to CPAP treatment.

Methods: We conducted a meta-analysis of data aggregated from published case reports of individual patient data up to April 2020. The quality of the reports was evaluated using the risk of bias in non-randomized studies of interventions (ROBINS-I) tool.

Results: A total of 13 cases (seven men and six women) from seven reports met our search criteria. Patients had mean age of 49.1 years (range = 36-62) and body mass index of 37.4 kg/m² (range = 27-56). Most had moderate to severe OSA with CPAP treatment. Nine cases had 24-hour urinary noradrenaline assessment before and after CPAP treatment. CPAP treatment led to a 21% reduction (104 nmol/24-hours, 95% credible interval =59 to 148) in 24-hour urinary noradrenaline to within reference ranges, and 25% reduction (from 131 to 100 mmHg) in mean arterial pressure. The risk of overall bias evaluated by the ROBINS-I tool was found to be low in the majority of reports.

Conclusions: Investigations of patients suspected of phaeochromocytoma, particularly obese individuals, should exclude OSA and treat this condition if present before performing screening tests to assess for catecholamine levels.