Diurnal rhythm of plasma catecholamines in acromegaly

We investigated the 24-h profiles of the circulating levels of norepinephri ne (NE) and epinephrine (E), blood pressure (BP), and heart rate in 14 acro megalic patients, before (A) and 3-6 months after transsphenoidal surgery ( C-R, cured; A-A, active), and in 8 age-matched normal subjects (N). In addi tion, the responses of NE, E, PRA, and aldosterone to upright posture were investigated. No significant differences in the mean 24-b plasma NE and E l evels were observed between either group of acromegalics and the N subjects . Analysis of the 24-h profiles indicated a statistically significant 24-h rhythm of both NE and E in N subjects. No evidence of a 24-h rhythm of plas ma NE and E and BP was found in A patients. After surgery, a statistically significant 24-h rhythm of NE was detected in the patients with acrophase ( 13.54 and 13.45 h in C-A and A-A patients, respectively) and mesor (1019.8 +/- 45.1 and 1017.8 +/- 54.7 pmol/L in C-A and A-A patients, respectively) similar to those observed in N subjects (acrophase, 13.21 h; mesor, 942.3 /- 42.5 pmol/L). After surgery, the plasma concentration of E clearly fluct uated throughout the 24 h in both C-A and A-A patients, even if cosinor ana lysis failed to reveal a 24-h significant rhythm. A statistically significa nt 24-h rhythm of BP was restored only in C-A patients. The mean 24-h heart rate was slightly, but significantly (P < 0.05), higher in A than in N sub jects and decreased after surgery. No significant differences in upright-st imulated NE, E, and plasma aldosterone levels were observed between each gr oup of acromegalics and N subjects. However, basal and upright-stimulated P RA levels were significantly (P < 0.001) lower in A patients. In conclusion, our study demonstrates the lack of a clear circadian variati on in catecholamine levels and BP in active acromegaly and the return of a significant 24-h rhythm of NE and BP after pituitary surgery, concomitant w ith the reduction in GH and insulin-like growth factor I serum levels.