Patients with end-stage renal disease on maintenance hemodialysis commonly develop hyperphosphatemia, a complication that is associated with increased mortality risk. While it is known that hyperphosphatemia contributes to vascular calcification, there are accumulating data that suggest an association with endothelial cell dysfunction.
Jinwoo Jung, MD, and colleagues conducted a cross-sectional study among patients on hemodialysis with hypertension. Results were reported in BMC Nephrology [doi:10.1186/s12882-022-02918-0].
The researchers obtained pre-hemodialysis measurements of total peripheral resistance index (TPRI, non-invasive cardiac output monitor) and plasma levels of endothelin-1 (ET-1) and asymmetric dimethylarginine (ADMA). They then determined the routine peridialytic blood pressure measurements from that treatment and the most recent pre-hemodialysis serum phosphate levels.
Independent associations between serum phosphate and blood pressure, TPRI, ET-1, and ADMA were determined using generalized linear regression analysis, while controlling for demographic variables, parathyroid hormone (PTH), and interdialytic weight gain.
The analyses included data from 54 patients. Mean prehemodialysis supine and seated systolic and diastolic blood pressures were 146, 158, 91.5, and 86.1 mm Hg, respectively. Mean serum phosphate was 5.89 mg/dL.
Phosphate was significantly correlated with all prehemodialysis blood pressure measurements (r=.03, P=.04; r=0.4, P=.002; r=0.5, P<.001; and r=0.5, P=.003, respectively). The correlations with phosphate and TPRI, ET-1, and ADMA were 0.3 (P=.01), 0.4 (P=.007), and 0.3 (P=.05), respectively.
After controlling for baseline characteristics, PTH, and interdialytic weight gain, the independent associations between phosphate and prehemodialysis diastolic blood pressure, TPRI, and ET-1 were retained.
“Serum phosphate concentration is independently associated with higher prehemodialysis blood pressure, vasoconstriction, and markers of endothelial cell dysfunction,” the researchers said. “These findings demonstrate an additional negative impact of hyperphosphatemia on cardiovascular health beyond vascular calcification.”