Comparative Effects of Haemodialysis and Haemofiltration on Plasma Atrial Natriuretic Peptide

The effects of 4 h haemodialysis (15 patients) or 4 h haemofiltration(five patients) on plasma concentrations of atrial natriureticpeptide (ANP) were compared by means of a sensitive radioreceptorbinding assay, and related to accompanying changes in body weight,blood pressure and plasma renin activity. Before dialysis, plasmaANP concentrations were considerably elevated: haemodialysisgroup 10–484 pmol/l (mean 156 pmol/l); haemofiltrationgroup 72–320 pmol/l (mean 170 pmol/l). Although plasmaconcentrations of ANP fell markedly with treatment in both groups:post-haemodialysis 2–187 pmol/l (mean 67 pmol/l); post-haemofiltration47–135 pmol/l (mean 79 pmol/l), after treatment it remainedabove the normal range in 14 of the 20 patients. Pretreatmentplasma ANP was related to systolic blood pressure (r=0.459;P<0.05) but bore no relationship to mean or diastolic bloodpressure, or plasma renin activity. The fall in plasma ANP concentrationduring treatment correlated with the postural blood pressuredrop after dialysis (r=0.505; P<0.05), but was unrelatedto changes in weight or plasma renin activity with haemodialysisor haemofiltration. Plasma ANP concentrations rose rapidly againin the 60 min after dialysis treatment, without change in bodyweight. These results show that high levels of biologically active ANPcirculate in end-stage renal disease. The fact that these arenot reduced to normal by haemodialysis or haemofiltration, despiterestoration to normovolaemic or hypovolaemic state, suggeststhat the increased levels of ANP in end-stage renal failureare due to both hypervolaemia and other factors, which may includeoccult cardiac dysfunction and loss of renal clearance.