Depressed levels of circulation menaquinones in patients with osteoporotic fractures of the spine and femoral neck

Vitamin K sub(1) 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 K sub(1) are depressed in osteoporotic patients. However, it is known that menaquinones (vitamin K sub(2):MK) may be more effective than vitamin K sub(1) 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 fracture. It is suggested that estimates of circulating levels of K sub(1), MK-7, and MK-8 might provide a biochemical risk marker of osteoporotic fractures.