Abstract
Optimal maintenance levels of intact PTH between 130 and 200pg/mL are recommended for the treatment of secondary hyperparathyroidism in patients undergoing hemodialysis therapy. It is known that the intact PTH level is affected by changes in serum Ca concentration. In this study, we investigated whether the intact PTH level was influenced by either serum Ca level or Vitamin D pulse injection therapy.
We simultaneously measured intact PTH and C-PTH levels using the same blood samples from 123 patients with chronic renal failure who were being treated at our hospital. Relationship between intact PTH and C-PTH was analyzed separately under several conditions, such as 1) difference in serum Ca level, 2) presence or absence of diabetes, and 3) with or without Vitamin D pulse injection therapy.
The slope of the C-PTH to intact PTH ratio differed in the high Ca group (more than 10.6mg/dL) being treated with conventional Vitamin D treatment, normal Ca group and low Ca group. Influence on intact PTH level due to changes in serum Ca was much higher on conventional Vitamin D therapy than on pulse therapy. The ratio of intact PTH to C-PTH was lower in the Vitamin D pulse therapy group than in the conventional treatment group. When patients were treated with Vitamin D pulse injection therapy, C-PTH remained high and the slope of the correlation line was shifted even if intact PTH levels decreased to 130-200pg/mL.
We conclude that the intact PTH level was affected by the concentration of Ca and Vitamin D pulse injection therapy. These findings indicate that data of serum Ca and C-PTH might provide useful information in the treatment of secondary hyperparathyroidism, especially measurement of C-PTH is useful when Vitamin D pulse injection therapy is being administered.
