Calcium scores and matrix Gla protein levels: association with vitamin K status.
BACKGROUND
Vascular calcification in humans is associated with an increased cardiovascular risk. Carboxylated matrix Gla protein (cMGP) inhibits vascular calcification. Vitamin K is an essential cofactor for the activation of uncarboxylated matrix Gla protein (ucMGP). It has been suggested that patients on long-term treatment with vitamin K antagonists develop aortic valve calcifications because of lower levels of circulating MGP. We therefore hypothesized that arterial calcification and a low vitamin K status are associated with ucMGP. To that aim, we measured arterial calcium scores, the osteocalcin ratio (OCR), as a proxy for vitamin K status, and ucMGP.


METHODS
In 36 hypertensive patients, we determined the Agatston score with computer tomography scans of the abdominal aorta, carotid and coronary arteries. The total calcium score was calculated as the sum of the separate Z-scores.


RESULTS
The total calcium Z-score was significantly correlated to age (r = 0.683, P < 0.001), smoking (r = 0.372, P = 0.026), total cholesterol (r = 0.353, P = 0.034), LDL cholesterol (r = 0.490, P = 0.003), triglycerides (r = 0.506, P = 0.002), fasting glucose (r = 0.454, P = 0.005), systolic blood pressure (r = 0.363, P = 0.029) and pulse pressure (r = 0.685, P < 0.001). In multivariate regression analyses, OCR and total calcium score were significantly associated with ucMGP.


CONCLUSIONS
We found a positive association of total arterial calcium score and a high OCR (reflecting low vitamin K status) with ucMGP serum levels. This warrants further studies to explore the pathophysiological background of this phenomenon.
Rennenberg
Roger J M W
RJ
Department of Internal Medicine, Maastricht University Medical Centre (MUMC+) and Cardiovascular Research Institute Maastricht (CARIM), Maastricht, The Netherlands. r.rennenberg@mumc.nl
de Leeuw
Peter W
PW
Kessels
Alphons G H
AG
Schurgers
Leon J
LJ
Vermeer
Cees
C
van Engelshoven
Jos M A
JM
Kemerink
Gerrit J
GJ
Kroon
Abraham A
AA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002114:Calcinosis; D002118:Calcium / Q000097:blood / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000097:blood / Q000378:metabolism*; D009202:Cardiomyopathies; D016326:Extracellular Matrix Proteins / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D006973:Hypertension; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000378:metabolism*; D014057:Tomography, X-Ray Computed; D014812:Vitamin K / Q000097:blood / Q000378:metabolism*; D000097568:Matrix Gla Protein
D002118:Calcium; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D015675:Osteocalcin; D014812:Vitamin K; D000097568:Matrix Gla Protein