DEPRESSED LEVELS OF CIRCULATING MENAQUINONES IN PATIENTS WITH OSTEOPOROTIC FRACTURES OF THE SPINE AND FEMORAL-NECK

Vitamin K1 functions in the conversion of glutamate residues, present in certain bone peptides, into the putatively active gamma-carboxyglutamate form. We have shown previously that the circulating levels of vitamin K1 are depressed in osteoporotic patients. However, it is known that menaquinones (vitamin K2:MK) may be more effective than vitamin K1 in this conversion of the inactive to active form of glutamate residues. A procedure for measuring such menaquinones has now demonstrated a marked deficiency of MK-7 and MK-8 in patients with osteoporotic fractures. It is suggested that estimates of circulating levels of K1, MK-7, and MK-8 might provide a biochemical risk marker of osteoporotic fractures.