Characterization of subtypes of hypertension in CAPD patients by cyclic guanosine monophosphate

Objective:While most hypertensive patients with endstage renal disease norm alize high blood pressure with fluid removal by continuous ambulatory perit oneal dialysis (CAPD), there is a significant proportion of CAPD patients w hose blood pressure can be controlled only by antihypertensive drugs. Method and Patients:To study the hypothesis that such patients are still vo lume overloaded, we used plasma cyclic guanosine monophosphate (cGMP) as a marker for hydration status. Thirty-two CAPD patients were divided into 3 g roups: group 1, normotensive patients (n = 12); group 2, hypertensive patie nts who normalized their blood pressure with fluid removal (n = 12); group 3, hypertensive patients whose blood pressure was refractory to intensified fluid removal (n = 8). Results: Mean cGMP levels were significantly higher in dialysis-sensitive h ypertension (27 +/- 5 pmol/ml) than in dialysis-refractory hypertension (15 +/- 2 pmol/ml), or in normotensive patients (13 +/- 4 pmol/ml). Reduction of excess fluid in volume overloaded hypertensive CAPD patients resulted in a normalization of cGMP levels (14 +/- 8 pmol/ml), but did not affect this volume marker in patients with dialysis-resistant hypertension (10 +/- 4 p mol/mL). Conclusion: Plasma cGMP levels are elevated in volume overload-induced hype rtension complicating CAPD. Hypertensive CAPD patients whose plasma cGMP le vels are within normal limits have raised blood pressure refractory to volu me removal. Our findings are consistent with the hypothesis that inadequate removal of excess volume plays a major role in a subset of patients with C APD hypertension.