Response of serum angiotensin converting enzyme, plasma renin activity and plasma aldosterone to conventional dialysis in patients on chronic haemodialysis.

The aim of this study was to examine serum angiotensin converting enzyme (SACE) activity and the renin-angiotensin-aldosterone system in patients on chronic haemodialysis during one routine dialysis session. Fourteen patients (8 men and 6 women; mean age 51.9 +/- 17 years) with end stage renal disease, receiving regular haemodialysis treatment for an average of 6 months, were studied. The patients were dialysed for 4 hours three times a week using cellulose membranes (cuprophan). After an overnight fast blood samples were taken from the patients before and after the haemodialysis session. Serum and plasma were separated and stored at -20 degrees C until assayed for SACE, plasma renin activity (PRA) and plasma aldosterone (PA). For comparison, SACE, PRA and PA were also measured in 8 patients after renal allotransplantation and on treatment with cyclosporin A (5 men, 3 women; mean age 38.9 +/- 12.3 years) and in 19 healthy subjects (13 men, 6 women; mean age 38.9 +/- 12.3 years). SACE levels in patients with chronic renal failure and on haemodialysis (17.55 +/- 9.03 nmol/ml/min) and in patients with renal transplantation (18.12 +/- 3.92) were significantly higher than those of the healthy subjects (9.27 +/- 1.67) (p < 0.0001, respectively). At the end of the dialysis session SACE levels in patients with chronic renal failure (14.9 +/- 7.19) did not increase in respect to pre-dialysis levels (17.55 +/- 9.03; p = 0.132). PRA and PA values increased after the dialysis session (p < 0.026 and p < 0.044, respectively). Correlation of SACE with PRA and PA was not demonstrated before or after the dialysis session. In patients with chronic renal failure and on haemodialysis our findings suggest that a disarrangement exists between the circulatory components of the reninangiotensin-aldosterone system before and after the dialysis session.