Plasma ANP and cGMP Levels in CAPD Patients

Abstract

Determining a dialysis patient`s dry-weight is an exercise that oftentaxes the clinical judgement of even the most astute nephrologist. This is all the more true for CAPD, where undetected hyperhydration may be even more frequent than in hemodialysis, because patients treat themselves at home and the ultrafiltration volume is less well predictable. Therefore, a reliable and easily accessible biochemical marker for the detection of fluid overload would substantially enrichthe diagnostic manual. It has repeatedly been shown that in chronic hemodialysis patients, the plasma levels of the atrial natriuretic peptide (ANP) and of its second messenger cyclic GMP (cGMP) are markedly elevated. The levels of both substances fall during ultra- filtration and thus reflect the hydration state. Previous studies from our laboratory have demonstrated a particularly close relation between the postdialytic plasma cGMP level and the hydration state in chronic hemodialysis patients. There are only few data on ANP and cGMP levels in CAPD. We conducted the following study in order to determine ANP and cGMP levels in patients treated with CAPD, to compare them with the ones found in hemodialysis and to assess their value as markers of fluid overload.