Association of hyperphosphataemia with haemodynamic disturbances in end-stage renal disease

Because recent data demonstrated that the shortened survival and excess cardiovascular death of end-stage renal disease (ESRD) patients are predicted by hyperphosphataemia, we examined the haemodynamic alterations associated with high serum phosphorus levels in ESRD patients on haemodialysis.

Sixty-six ESRD patients were studied. Patients were separated arbitrarily into two groups, i.e. with predialysis serum phosphate <2 mmol/l ('normal' phosphate) and, serum phosphate >2 mmol/l ('high' phosphate). Cardiac and arterial function and structure were analysed by computer-assisted ultrasonography.

Hyperphosphataemic patients were characterized by higher diastolic and mean blood pressures (P<0.05), and higher cardiac index (P<0.001) caused by an increased stroke index (P<0.05) and higher heart rate (P<0.01). The cardiac work index was significantly increased in patients with higher phosphate levels (P<0.01). Hyperphosphataemic patients tended to have a higher common carotid artery diameter (P=0.07), but similar carotid artery intima-media thickness, and lower carotid wall-to-lumen ratio (P<0.05) than patients with 'normal' serum phosphorus. As a result of lower wall-to-lumen ratio in the presence of higher mean blood pressure, the carotid tensile stress was higher in hyperphosphataemic ESRD patients (P<0.05).

These findings suggest that, in stable ESRD patients, hyperphosphataemia is associated with increased BP, hyperkinetic circulation, increased cardiac work, and high arterial tensile stress. These haemodynamic abnormalities could favour the development of cardiovascular complications and contribute to high cardiovascular morbidity and mortality.