Plasma pyrophosphate and vascular calcification in chronic kidney disease.
BACKGROUND
Pyrophosphate (PPi) is a potent inhibitor of vascular calcification and may be deficient in renal failure. We sought to determine whether plasma PPi is affected by dialysis or the mode of dialysis and whether it correlates with vascular calcification.


METHODS
PPi was measured in plasma samples stored from a recent study of vascular calcification in 54 HD patients, 23 peritoneal dialysis (PD) patients and 38 patients with stage 4 chronic kidney disease (CKD). Calcification was quantified in a standardized section of the superficial femoral artery using computed tomography, and PPi was measured by enzyme assay, at both baseline and 1 year.


RESULTS
Baseline plasma PPi was weakly correlated with age and serum phosphate, but not with alkaline phosphatase activity or other biochemical parameters, and did not differ between HD, PD and CKD patients. Both baseline calcification score and change in the calcification score at 1 year decreased with increasing quartiles of plasma PPi. In a multivariate analysis, plasma PPi was independently correlated with baseline calcification (P = 0.039) and the change in calcification (P = 0.029).


CONCLUSIONS
Plasma PPi is negatively associated with vascular calcification in end-stage renal disease (ESRD) and CKD but is not affected by dialysis, the mode of dialysis or nutritional or inflammatory status. Although these data are consistent with an inhibitory effect of PPi on vascular calcification, further studies are needed to establish a causal role.
O'Neill
W Charles
WC
Renal Division, Department of Medicine, Emory University, Atlanta, GA, USA. woneill@emory.edu
Sigrist
Mhairi K
MK
McIntyre
Christopher W
CW
D000368:Aged; D002114:Calcinosis / Q000097:blood* / Q000000981:diagnostic imaging*; D002908:Chronic Disease; D011756:Diphosphates / Q000097:blood*; D005260:Female; D005263:Femoral Artery / Q000000981:diagnostic imaging; D006801:Humans; D007674:Kidney Diseases / Q000097:blood* / Q000628:therapy*; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010530:Peritoneal Dialysis; D006435:Renal Dialysis; D014057:Tomography, X-Ray Computed
D011756:Diphosphates