ATRIAL-NATRIURETIC-FACTOR IN PATIENTS WITH ACROMEGALY

In acromegaly the plasma volume is chronically elevated and it returns to normal when the disease is successfully treated. To define the role of ANF in such a chronic disorder of extracellular fluid volume homeostasis the plasma level was assayed in 37 acromegalic patients with active or inactive (successfully treated) disease. Five patients were studied before and after therapy. The effects of acute change in sodium-fluid status on plasma ANF levels was examined in 7 active and 4 inactive acromegalic patients and in 7 healthy subjects. As compared to 14 patients with inactive acromegaly, 23 patients with active acromegaly had an expanded plasma volume (n=12; 50.1 vs 37.6 ml · kg-1 BW) and an increased blood concentration of growth hormone (n=23; 22.5 vs 2.1 ng · ml-1). Plasma ANF concentrations in active and inactive acromegalic patients (33.2 and 26.6 pg · ml-1, respectively) did not differ significantly from one another or from the level in the controls (26.9 pg · ml-1). In those patients there was no correlation between plasma volume and ANF level. Infusion of 21 isotonic saline in 2 h led to a similar, significant increase in ANF levels in active (from 26.2 to 72.4 pg · ml-1) and in inactive acromegalic patients (from 33.6 to 96.7 pg · ml-1) as well as in healthy subjects (from 21 to 70.6 pg · ml-1). Successful treatment reduced the plasma volume (from 49.2 to 35.8 ml · kg-1 BW) and growth hormone level (from 10.1 to 2.6 pg · ml-1), while the ANF level remained unchanged (from 33.8 to 35.5 pg · ml-1). In the patients with active or inactive acromegaly and cardiac failure the plasma ANF level was markedly increased (89.9 and 66.1 pg · ml-1, respectively) as compared to all the other groups. It is concluded that ANF levels are not elevated in chronically volume expanded acromegalic patients. In the present patients ANF was released in response to acute volume expansion, therefore it may be important in the cardiovascular and renal response to acute changes in extracellular fluid volume. © 1990 Springer-Verlag.