Secondary hyperparathyroidism in patients on maintenance hemodialysis.

I measured levels of serum immunoreactive C-terminal and N-terminal parathyroid hormone (PTH), total serum calcium and ionized serum calcium in patients treated by hemodialysis. There was a correlation between the C-terminal PTH and N-terminal PTH levels. N-terminal PTH levels were not influenced by the age of the patients, but they increased as the period of hemodialysis became longer. The correlation between the level of N-terminal PTH and secondary hyperparathyroidism was good, but there was no correlation between the level of C-terminal PTH and secondary hyperparathyroidism.