Urinary cGMP concentrations in severe primary pulmonary hypertension

Background-Prognostic evaluation of patients with primary pulmonary hyperte nsion (PPH) requires right heart catheterisation. The development of accura te non-invasive methods for monitoring these patients remains an important task. Cyclic guanosine monophosphate (cGMP) is an indicator of the action o f natriuretic peptides and nitric oxide on target cells. Plasma and urinary cGMP concentrations are raised in patients with congestive heart failure i n whom they correlate closely with haemodynamic parameters and disease seve rity. The aim of the present study was to determine whether the urinary con centration of cGMP could be used as a non-invasive marker of haemodynamic i mpairment in patients with severe PPH. Methods-Urinary cGMP concentrations were measured in 19 consecutive patient s with PPH, seven with acute asthma, and 30 normal healthy controls. Result-Patients with PPH had higher urinary cGMP concentrations than asthma tic patients or normal healthy controls (p = 0.001). Urinary cGMP concentra tions were higher in patients with severe haemodynamic impairment-that is, those with a cardiac index (CI) of less than or equal to 2 1/ min/m(2) (p = 0.002)-and urinary cGMP concentrations were inversely correlated with CI ( r = -0.69, p = 0.002) and venous oxygen saturation (r = -0.65, p = 0.003). Conclusion-Urinary cGMP concentrations may represent a non-invasive indicat or of the haemodynamic status of patients with severe PPH.