Plasma Atrial Natriuretic Peptide Levels in Continuous Ambulatory Peritoneal Dialysis Patients

Hikaru Koide, MD, Division of Nephrology, Department of Medicine, Koto Hospital, 6-8-5 Ojima, Koto-ku, Tokyo 136 (Japan) Dear Sir, The cardiothoracic ratio (CTR) as determined from the chest x-ray is a simple and noninvasive method for determining the presence of volume overload, although it is not consistently reliable. The present study showed the plasma level of atrial natriuretic peptide (hANP) to be a more reliable method for determining the volume overload status in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). We studied 73 CAPD patients (46 males, 27 females) aged 15-68 years (mean 45.2) without overt edema or uncontrolled hypertension (mean blood pressure ≥ 110 mm Hg). The duration of CAPD ranged from 2 to 64 months (mean 25.6). All patients received standard peritoneal dialysis fluid (Dianeal® PD-2; Baxter Healthcare), 1.5, 2.5 or 4.25%, and four exchanges of 2 liters of dialysate daily. None of the patients had peritonitis at the time of the study or in the previous 4 weeks. Dietary sodium intake was restricted to 7 g/day. Blood samples were collected in the morning for plasma hANP assay from the 73 CAPD patients and from 39 age-matched healthy control subjects (26 males, 13 females) after they had rested in the supine position for approximately 30 min. Plasma hANP was measured by a specific and sensitive radioimmunoassay [ 1 ]. Recovery of synthetic hANP by this method was 96.7%. Results are presented as the mean ± SD. The significance of differences was analyzed by Student’s t test for unpaired data. A level of p < 0.05 was accepted as statistically significant.