Abstract
Although the administration of vitamin K2 (menatetrenone) has been reported to improve the bone mineral density in patients with postmenopausal and senile osteoporosis, the role of the K vitamins in the bone diseases of dialysis patients is not well defined. In this study, we investigated the role of the K vitamins as clinical markers of bone metabolism in dialysis patients.
We measured the concentrations of vitamin K1 (phylloquinone) and vitamin K2 (menaquinone-4, 7) and clinical markers of bone metabolism in 47 chronic dialysis patients including 18 hemodialysis patients (10 men and 13 women, whose age ranged from 27 to 62 years with a mean of 45 years; duration of dialysis ranged from 12 to 108 months) and 29 peritoneal dialysis patients (16 men and 13 women, whose age ranged from 23 to 68 years with a mean of 48 years; duration of dialysis ranged from 4 to 236 months). Plasma phylloquinone concentration in all dialysis patients was measurable (0.73±0.54ng/ml). Plasma menaquinone-4 was undetectable in 44 of the 47 patients. The plasma menaquinone-7 concentration was 1.18±0.84ng/ml in 24 patients and undetectable in the others. The plasma phylloquinone concentration in the patients with undetectable amounts of menaquinone-7 was lower than that in the patients with detectable menaquinone-7 (0.94±0.90ng/ml vs. 1.70±1.35ng/ml, p<0.05). There were no significant differences in the plasma levels of the K vitamins between men and women and between hemodialysis patients and peritoneal dialysis patients. There was a significant correlation between the plasma phylloquinone level and the plasma intact-PTH level (p<0.05). The plasma phylloquinone level in the patients who had a serum intact-PTH level more than 90pg/ml was higher than that in the patients with a serum intact-PTH level less than 90pg/ml (0.82±0.80ng/ml vs. 0.55±0.56ng/ml, p<0.05). In female dialysis patients except those with an undetectable menaquinone-7 level, the bone mineral density in the lateral spine decreased significantly (p<0.05) in proportion to the increase in the menaquinone-7 level. There was no correlation between the plasma levels of the K vitamins and the normalized protein catabolic rates in the peritoneal dialysis patients.
These results indicate that the plasma phylloquinone and menaquinone-7 levels in dialysis patients are lower than those in healthy subjects, suggesting that administration of K vitamins may improve the bone metabolism in dialysis patients.
