Renal patients have an increased risk for cardiovascular complications. There is also increased vascular calcification and bone metabolism is similarly abnormal in patients with chronic kidney disease.

In dialysis patients frequent episodes of hypercalcaemia occur. In a healthy bone structure those episodes of hypercalcemia are buffered by the bone. The absence of bone buffering capacity in dialysis patients can be a mechanism for vascular calcifications.

Study hypothesis.

Patient with a higher ∆ Calcium (Calcium post - Calcium pre) have a diminished bone buffering capacity indicative for adynamic bone disease compared with patients with smaller ∆ Calcium.

This may result in higher extraosseous calcification and higher pulse wave velocity

∆ PTH/∆ Calcium may reflect the sensitivity and density of the calcium receptors; this may reflect parathyroid "health"

Inclusion Criteria:

• maintenance hemodialysis patients

Exclusion Criteria:

• dialysis <3 months
• aortobifemoral graft
• calcium level predialysis >10.5 mg/dl