Abstract
The relationship between phosphorus metabolism and PTH was studied in regular hemodialysis patients.
In 123 hemodialysis patients there was a negative correlation between phosphorus and ionized calcium and a positive correlation between phosphorus and ionized calcium and a positive correlation between phosphorus and PTH, but there was no significant correlation between ionized calcium and PTH.
In 420 sets of data for 36 hemodialysis patients followed for over one year we discovered a positive correlation between phosphorus and PTH and between ionized calcium and PTH, but not between phosphorus and ionized calcium.
In phosphorus groups classified by 1mg/dl differences in serum levels, increases in PTH were dependent on increases in phosphorus, but there were no significant differences in ionized calcium among the phosphorus groups. The HS-PTH levels in 3 groups (phosphorus 5mg/dl group, 6mg/dl group and 7mg/dl group) were significantly higher than in the below 4mg/dl group. When HS-PTH levels were compared in 3 groups, the below 4mg/dl group (HS-PTH: 10.5±13.4ng/ml), the 4-6mg/dl group (HS-PTH; 18.8±20.2ng/ml) and the over 6mg/dl group (HS-PTH: 23.2±20.8ng/ml), the HS-PTH levels in much-higher-phosphorus group in the over 6mg/dl group were found to be significantly higher than in the other groups. The phosphorus level in the over 15ng/ml HS-PTH group (6.4±1.6mg/dl) was significantly higher than in the below 15ng/ml HS-PTH group (5.7±1.6mg/dl). The ionized calcium significantly higher levels in the high HS-PTH group was an unexpected finding.
In conclusion, we suspect that the mechanism by which phosphorus regulates PTH secretion in regular hemodialysis patients is not stimulation by ionized calcium but by other factors.
