A controlled trial of the early treatment of secondary hyperparathyroidism with calcitriol in hemodialysis patients.
BACKGROUND
Calcitriol is widely used in conjunction with phosphorus-binders containing calcium to treat secondary hyperparathyroidism in dialysis patients. Its efficacy in patients with severe hyperparathyroidism is diminished, in part, due to glandular hyperplasia associated with decreased calcitriol and calcium receptors.


METHODS
We, therefore, developed a prospective, randomized trial comparing i.v. calcitriol plus calcium carbonate (CaCO3) compared to CaCO3 alone (control) in patients with mild to moderate hyperparathyroidism who were within the first year of initiating hemodialysis. Patients underwent calcium (Ca) suppression/stimulation testing at baseline and after six and twelve months of treatment to indirectly assess parathyroid gland hyperplasia.


RESULTS
In the calcitriol group, the amino-terminal parathyroid hormone (N-PTH) decreased significantly from a baseline value of 70 +/- 12 pg/ml at month zero to 22 +/- 7 and 19 +/- 6 pg/ml at months 6 and 12, respectively (the conversion factor of amino-terminal PTH to intact PTH is 6, i.e., 10 pg/ml N-PTH equals 60 pg/ml intact PTH). In contrast, the N-PTH levels in the CaCO3 alone group did not change. The change in nadir N-PTH levels at month 12 compared to month zero decreased by 14 +/- 7% in the calcitriol group but increased by 96 +/- 59% in the control group (p < 0.05). In addition, the increment in N-PTH levels during hypocalcemic stimulation decreased by 68 +/- 6% at month 12 compared to month zero but increased by 61 +/- 42% in the control group. Although total calcium and phosphorus levels were not different between the two groups, ionized calcium values were higher in the calcitriol group. The incidence of hypercalcemia was the same in both groups and the episodes were asymptomatic.


CONCLUSIONS
Pulse calcitriol therapy is effective in preventing progression of secondary hyperparathyroidism in hemodialysis patients with mild to moderate disease. Based on Ca suppression/stimulation tests, calcitriol was more successful in preventing gland growth than CaCO3 alone. Further studies are needed to determine if the strategy of early treatment of mild to moderate hyperparathyroidism by pulse calcitriol is safe and effective in hemodialysis in patients.
Delmez
J A
JA
Renal Division and Chromalloy American Kidney Center, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA.
Kelber
J
J
Norwood
K Y
KY
Giles
K S
KS
Slatopolsky
E
E
D002117:Calcitriol / Q000627:therapeutic use*; D002118:Calcium / Q000097:blood; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000188:drug therapy*; D010758:Phosphorus / Q000097:blood; D006435:Renal Dialysis; D013997:Time Factors
D010758:Phosphorus; D002117:Calcitriol; D002118:Calcium