Gammacarboxyglutamate (Gla) is an uncommon amino acid formed by vitamin K action. Increasing evidence indicates that Gla-proteins
are involved in the regulation of calcification processes in both bone tissue and atherosclerotic vessel wall. In a population-based
study we have previously shown that in a group of 113 postmenopausal women the presence of abdominal aortic calcifications
is associated with a reduced vitamin K status. In the present study we investigated whether this reduced vitamin K status
was also associated with differences in bone mass or circulating calciotropic hormone levels. Serum immunoreactive osteocalcin
with low affinity for hydroxyapatite (irOC
free) was used as a marker for vitamin K status. After correction for age it was found that women with atherosclerotic calcifications
had a 7% lower bone mass as measured by metacarpal radiogrammetry (mean difference: 3.2 mm
2, 95% CI: −0.2–6.5,
P= 0.06). No differences between both groups of women were observed for serum intact parathyroid hormone (PTH) and serum 25-hydroxyvitamin
D levels. In the atherosclerotic women (n = 34), markers for vitamin K status were inversely associated with bone mass (r
=−0.47,
P= 0.013), whereas no such association was found in the nonatherosclerotic women (n = 79). It is concluded that the atherosclerotic
women in this study may be at higher risk for osteoporotic fractures as evidenced by their lower bone mass and higher serum
irOC
free levels. The finding that in atherosclerotic women vitamin K status is associated with bone mass supports our hypothesis that
vitamin K status affects the mineralization processes in both bone and in atherosclerotic plaques.
Key words: Vitamin K – Gammacarboxyglutamate — Osteocalcin — Calcification — Atherosclerosis — Bone mass.
Received: 15 January 1996 / Accepted: 3 May 1996