Protective Effect of Vitamins K₂ and D₃ on Prednisolone-Induced Loss of Bone Mineral Density in the Lumbar Spine

Background: Although vitamin K₂ has been shown to prevent prednisolone-induced loss of bone mineral density of the lumbar spine in patients with chronic glomerulonephritis, the magnitude of this effect remains to be clarified. The aim of this prospective study is to compare the protective effect of vitamin K₂ with that of vitamin D₃ on prednisolone-induced loss of bone mineral density in patients with chronic glomerulonephritis. Methods: Sixty patients (28 men, 32 women) were randomly divided into 4 groups (n = 15 each group): control (group C), vitamin D ₃ alone (alfacalcidol, 0.5g μg/d; group D), vitamin K₂ alone (menatetrenone, 45 mg/d; group K), and vitamins D₃ plus K ₂ (group D + K). Alfacalcidol and menatetrenone therapy were started at the same time as prednisolone. Bone mineral density of the lumbar spine (L2 to L4) was determined by means of dual-energy X-ray absorptiometry, and various biochemical parameters of calcium and bone homeostasis were assessed before and at the end of week 8 of treatment. Results: Treatment with prednisolone alone caused loss of bone mineral density, which could be fully prevented in groups D, K, and D + K. However, marked reductions in levels of several biochemical markers of both bone formation and resorption also were observed in all groups. The preventive effect in groups K and D + K on loss of bone mineral density induced by prednisolone was similar to that in group D. The elevation in serum calcium levels observed in group D was attenuated in group D + K. Conclusion: Protective effects of vitamin K₂ or vitamins D₃ and K ₂ on prednisolone-induced loss of bone mineral density are similar to that of vitamin D₃.