Objective To explore the relationship between serum phosphate, arterial stiffness and left ventricular mass (LVM) in patients with early-stage chronic kidney disease (CKD).

Design A cross-sectional observational study.

Setting Single centre.

Patients 208 patients with stage 2 to stage 4 non-diabetic CKD.

Interventions Arterial stiffness was determined through measurement of aortic pulse wave velocity (PWV). Cardiac magnetic resonance was used to determine LVM.

Main outcome measure Relationship between serum phosphate, aortic PWV and LVM.

Results Mean age was 54±13 years, mean glomerular filtration rate was 50±15 ml/min/1.73 m², mean serum phosphate was 1.11±0.21 mmol/l and mean PWV was 8.6±2.1 m/s. When the cohort was divided into quartiles according to serum phosphate, LVM increased across quartiles (p=0.04), with no significant differences in age, kidney function, blood pressure or PWV. Serum phosphate correlated with LVM (r=0.173; p=0.01), but PWV did not (p=0.2). In a regression model containing gender, serum phosphate, office systolic blood pressure, albumin/creatinine ratio and haemoglobin, 30% of the variation in LVM was explained (p<0.0005), with serum phosphate accounting for 5% of the variance.

Conclusion Serum phosphate is independently associated with LVM in patients with CKD. Interventional studies are required to determine whether this association is causative and whether reducing phosphate exposure reduces LVM in this population.