Plasma alpha-human atrial natriuretic peptide and volume status in chronic haemodialysis patients.

The relationship between inferior vena cava diameter (VCD), collapse-index (CI) determined by echography, and alpha-human atrial natriuretic peptide (alpha-h-ANP) concentrations were studied in 19 chronic haemodialysis patients. A significant correlation was found between VCD and alpha-h-ANP before dialysis (r = 0.78; P less than 0.0001). No such correlation was found between CI, left atrial diameter and left ventricular end-diastolic diameter, and alpha-h-ANP values. In nine patients who according to vena cava indices were hypervolaemic before dialysis (group I), alpha-h-ANP concentrations were significantly greater than in ten normo- or hypovolaemic patients (group II): 392.8 +/- 134.1 pg/ml and 168.0 +/- 62.5 pg/ml respectively. Although the same amount of fluid was ultrafiltrated in both groups, alpha-h-ANP decreased significantly in group I only, whereas in group II the decrease was not significant: 392.8 +/- 134.1 to 185.2 +/- 81.7 (P less than 0.001); 168.0 +/- 62.5 to 130.0 +/- 59 respectively. After achieving normovolaemia alpha-h-ANP concentrations in patients with a mitral valve insufficiency grade I was doubled compared to normovolaemic patients without mitral valve insufficiency, suggesting that alpha-h-ANP release will also occur from the left atrium. In the latter group alpha-h-ANP values were approximately doubled compared to healthy controls. The highly significant correlation between VCD before dialysis and changes in alpha-h-ANP during dialysis with fluid removal underlines the value of vena cava diameter in estimating volume status.