Plasma concentration of human atrial natriuretic polypeptide in patients with impaired renal function

Using direct radioimmunoassay, the plasma concentration of human atrial natriuretic polypeptide (hANP) was measured in patients with impaired renal function. Patients on maintenance hemodialysis (HD) and those still on medical management (non-HD) were examined. In 13 non-HD patients with serum creatinine values from 2.0 to 8.3 mg/dl, mean plasma hANP (+/- SE) was 404 +/- 23 pg/ml, while it was 236 +/- 11 pg/ml in the normal control group (n = 15) and the difference was significant (p less than 0.001). In all patients as a whole, there was a positive correlation between plasma hANP and mean blood pressure (r = 0.56, p less than 0.05) but no correlation was present between plasma hANP and renal function. Fifty-six HD patients were divided into 2 groups depending on blood pressure level. Plasma levels of hANP in the hypertensive (BP greater than or equal to 150/90 mmHg, n = 21) and in the normotensive (BP less than 150/90 mmHg, n = 35) HD group were 588 +/- 58 pg/ml and 364 +/- 29 pg/ml, respectively, with plasma hANP in both HD groups significantly higher than in the controls (p less than 0.001). There was also a significant difference of plasma hANP between hypertensive and normotensive HD patients (p less than 0.01). However, when the normotensive HD group without cardiomegaly (cardiothoracic ratio less than 50%, n = 17) was compared with the control, the value of plasma hANP was not statistically different from that of the control group. These results suggest that plasma hANP in patients with impaired renal function is influenced by blood pressure and/or cardiac condition.