Abstract
Introduction:
Vitamin K (VK) as well as vitamin D (VD) play an important role in osteoporosis. Vitamin K1 (VK1) and vitamin K2 (VK2, menaquinone-4 (MK-4) and menaquinone-7 (MK-7)) are significant for the metabolism of skeletal muscle. 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 (25(OH)D2 and 25(OH)D3) reflect circulating VD levels. More sensitive measurements remains to be developed. In the present study, a new high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of VK1, VK2(MK-4 and MK-7) as well as 25(OH)D2 and 25(OH)D3 levels in human serum.
Methods:
We developed a simple LC-MS/MS method for the determination of VK1, MK-4, MK-7, 25(OH)D2 and 25(OH)D3 levels in human serum and validated the method in a study cohort of 200 patients divided into the premenopausal women group and postmenopausal osteoporosis patient group.
Results:
The overall precision (coefficient of variation, CV) ranged from 2.66-10.11% in the specified working range (0.05-5 ng/mL) for VK1, MK-4 and MK-7. Serum VK1, MK-4 and MK-7 levels in postmenopausal women with osteoporosis were 1.187 ± 0.0.094 ng/mL, 0.058 ± 0.009 ng/mL and 0.885 ± 0.064 ng/mL, respectively (mean ± standard deviation, SD). Serum VK1, MK-4 and MK-7 levels in premenopausal women were 1.143 ± 0.103 ng/mL, 0.028 ± 0.003 ng/mL and 1.553 ± 0.226 ng/mL, respectively. Serum 25(OH)D2 and 25(OH)D3 levels in postmenopausal women with osteoporosis were 0.757 ± 0.056 ng/mL and 11.72 ± 0.632 ng/mL, respectively. Serum 25(OH)D2 and 25(OH)D3 levels in premenopausal were 1.793 ± 0.575 ng/mL and 12.42 ± 1.069 ng/mL, respectively.
Conclusion:
A new LC-MS/MS method for determination of serum VK and VD levels was evaluated and validated. MK-7 in plasma decreased earlier than VD in postmenopausal osteoporosis patients. MK-7 status is significantly associated with osteoporosis and could be considered a predictable biomarker in the diagnosis of osteoporosis in postmenopausal women.
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