Pyrophosphate and Arterial Calcification in Chronic Kidney Disease (Predical)

Arterial calcifications start at early stages of chronic kidney disease (CKD) and are associated to cardiovascular mortality. Pyrophosphate (PPi) is an endogenous compound, which stops the mineralization process in bones and is expected to act at ectopic sites. In uremic rats, low PPi plasma levels are associated with high calcium content in the aorta and peritoneal administration of PPi blocks this process. People on maintenance dialysis or kidney transplant recipients have low plasma levels of PPi and show high scores of arterial calcification. The purpose is to determine the role of low PPi in the development of arterial calcifications in patients with CKD stage 3 or 4. To that aim, 252 patients with eGFR between 59 et 20 ml/min/1,73 m2 will be recruited and will be examined at baseline and three years later.

The investigator will collect the usual clinical history and data. Risk factors and cardiovascular events are identified. A blood sample dedicated to the study and necessary for routine care is taken. The pulse wave velocity and systolic pressure index are measured. A myocardial CT scan coupled with a computed tomography is performed. The patient collects stools at his home, simply conditions them and sends them by mail to the centre, which stores them.

A blood sample dedicated to the study and necessary for routine care is taken. The pulse wave velocity and systolic pressure index are measured. A myocardial CT scan coupled with a computed tomography is performed. The patient collects stools at his home, simply conditions them and sends them by mail to the centre, which stores them.

To show that low plasma levels of PPi at baseline is associated with a high progression of arterial calcification at three years after adjustment for confounding variables

Inclusion Criteria: eGFR between 59 et 20 ml/min/1,73 m2 twice at three month interval Exclusion Criteria: kidney transplantation acute inflammatory disease or active cancer