Abstract :
[en] Background: Matrix Gla protein (MGP) is known to act as a potent local inhibitor of vascular calcifications.
However, in order to be active, MGP must be phosphorylated and carboxylated, with this last process being
dependent on vitamin K. The present study focused on the inactive form of MGP (dephosphorylated and
uncarboxylated: dp-ucMGP) in a population of hemodialyzed (HD) patients. Results found in subjects being treated
or not with vitamin K antagonist (VKA) were compared and the relationship between dp-ucMGP levels and the
vascular calcification score were assessed.
Methods: One hundred sixty prevalent HD patients were enrolled into this observational cohort study, including
23 who were receiving VKA treatment. The calcification score was determined (using the Kauppila method) and
dp-ucMGP levels were measured using the automated iSYS method.
Results: dp-ucMGP levels were much higher in patients being treated with VKA and little overlap was found with
those not being treated (5604 [3758; 7836] vs. 1939 [1419; 2841] pmol/L, p <0.0001). In multivariate analysis,
treatment with VKA was the most important variable explaining variation in dp-ucMGP levels even when adjusting
for all other significant variables. In the 137 untreated patients, dp-ucMGP levels were significantly (p < 0.05) associated
both in the uni- and multivariate analysis with age, body mass index, plasma levels of albumin, C-reactive protein, and
FGF-23, and the vascular calcification score.
Conclusion: We confirmed that the concentration of dp-ucMGP was higher in HD patients being treated with VKA. We
observed a significant correlation between dp-ucMGP concentration and the calcification score. Our data support the
theoretical role of MGP in the development of vascular calcifications. We confirmed the potential role of the inactive
form of MGP in assessing the vitamin K status of the HD patients.
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