Pronounced elevation of undercarboxylated osteocalcin in healthy children.
The vitamin K-dependent protein osteocalcin is thought to play an important role in bone metabolism. Osteocalcin contains glutamic acid (Gla) residues, which have a high affinity for calcium. Vitamin K acts as an indispensable cofactor for the formation of these residues. Inadequate dietary vitamin K intake results in the synthesis of undercarboxylated (i.e. inactive) osteocalcin (ucOC). In adults, low vitamin K status of bone is associated with low bone density and increased risk of osteoporotic fractures. Little is known about vitamin K status and bone health in children. We used a cross-sectional study design to compare the vitamin K status of bone in healthy children (n = 86) with that of adults (n = 30). In children, a marked elevation of the ratio of ucOC/carboxylated osteocalcin (cOC), indicative of a poor vitamin K status, was observed. This difference persisted after adjusting for age, gender, puberty, height, weight. Furthermore, a marked correlation between the bone markers for bone metabolism and ucOC and cOC was found in the children's group. These findings suggest a pronounced low vitamin K status of bone during growth. The question remains, however, whether children would benefit from higher vitamin K intake, for instance, by improved bone health or stronger bones.
van Summeren
Marieke
M
Department of Pediatric Immunology, University Medical Centre Utrecht, 3584 EA Utrecht, The Netherlands.
Braam
Lavienja
L
Noirt
Florence
F
Kuis
Wietse
W
Vermeer
Cees
C
D000293:Adolescent; D000328:Adult; D001842:Bone and Bones / Q000378:metabolism; D002264:Carboxylic Acids / Q000737:chemistry; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015675:Osteocalcin / Q000097:blood* / Q000737:chemistry; D012016:Reference Values; D014812:Vitamin K / Q000008:administration & dosage / Q000378:metabolism
D002264:Carboxylic Acids; D015675:Osteocalcin; D014812:Vitamin K