Catecholamine excretion and circadian blood pressure profile in patients with pheochromocytoma

Circadian blood pressure (BP) rhythm is often disturbed in patients with secondary forms of hypertension. The aim of the present article was to investigate changes in circadian BP profile parameters using two-step statistical approach by Fourier analysis in relation to day and night urinary catecholamine excretion in 35 patients with pheochromocytoma (mean age 42+/-19 years). Twenty-four-hour ambulatory BP measurements (ABPM) were obtained using the SpaceLabs 90,207 monitor. Daytime and night-time urine collection was obtained in all patients to determine circadian catecholamine excretion. Fourier analysis was applied to estimate measures of BP circadian rhythm in ABPM, including the highest (Max) and lowest (Min) systolic (SBP) and diastolic (DBP) BP values, norad (ampSBP, ampDBP), and early acrophase (APSBP, APDBP). The Fourier indices of circadian BP rhythm were: MaxSBP 153+/-28 mm Hg, MaxDBP 99+/-16 mm Hg, MinSBP 117+/-17 mm Hg, MinDBP 69+/-11 mm Hg, ampSBP 18+/-8 mm Hg, ampDBP 14+/-5 mm Hg, APSBP 10+/-5 (h), and APDBP 11+/-3 (h). Urine noradrenaline (NA), adrenaline (A), and dopamine (DA) excretion during the day (d) and night (n) were: dNA 103.5+/-89.8 microg/14 h, nNA 52+/-70.8 microg/10 h, dA 13.2+/-17.9 microg/14 h; nA 6.13+/-9.6 microg/10 h, dD 181.8+/-87.3 microg/14 h, and nD 89.3+/-59.8 microg/10 h. A positive correlation was observed between urine dNa excretion and MaxDBP (r=0.37, P<0.05), and urine nNA and urine dA excretion were correlated with APDBP (r=0.47, r=0.35, respectively, both P<0.05). Thus, in addition to the effect on mean 24-h BP values, catecholamines released by tumor may also disturb circadian BP rhythm in patients with pheochromocytoma.