PLASMA CGMP LEVEL AS A MARKER OF THE HYDRATION STATE IN RENAL REPLACEMENT THERAPY

We investigated, whether plasma cyclic guanosine 3':5'-monophosphate ( cGMP) may be suited as a marker of hyperhydration in hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD). In 81 HD patien ts the levels of atrial natriuretic peptide (ANP) and cGMP were marked ly elevated before HD (ANP: 165 +/- 11.1 pg/ml; cGMP 43.5 +/- 2.2 pmol /ml). Significantly lower values (P < 0.01) were found after HD (ANP: 97 +/- 8.4 pmol/ml; cGMP 19.5 +/-1.5 pmol/ml). Twenty-three patients h ad cGMP levels above 20 pmol/ml after HD. Therefore ''dry body weight' ' was reduced in these patients. This resulted in a ''normalization'' of cGMP values to a postdialytic range below 20 pmol/ml in the majorit y of patients. All seven patients with persistently high cGMP levels d espite weight reduction had left sided heart failure. In 33 CAPD patie nts ANP was slightly lower than after HD (68 +/- 10.4 pg/ml), and the cGMP level (22.4 +/- 2.3 pmol/ml) was between pre- and postdialytic va lues in HD. In eight CAPD patients with clinical signs of hypervolemia plasma cGMP, but not ANP, was significantly elevated. We conclude tha t the plasma cGMP level appears to be a reliable marker for fluid over load in patients on renal replacement therapy with normal heart functi on.