Acute and one-year effects of cinacalcet in patients with persistent primary hyperparathyroidism after unsuccessful parathyroidectomy.

OBJECTIVE

We report the acute effects of cinacalcet on calcium and parathyroid hormone (PTH) levels and the effects of 1 year of therapy on calcium and phosphorus metabolism in 4 patients with persistent primary hyperparathyroidism (PHPT) after unsuccessful parathyroidectomy.

PATIENTS: Four patients (3 women; age, 24 to 71 years) were studied after 1 to 3 parathyroid operative procedures. All of them had elevated serum total and ionized calcium levels, decreased serum phosphorus, and increased concentrations of intact PTH.

METHODS

Calcium and PTH responses to an acute dose of oral cinacalcet (30 mg) were studied at baseline. Effects of cinacalcet (30 mg b.i.d.) on serum calcium, phosphorus, and PTH, and urinary calcium and phosphorus were studied at 1, 3, 6, and 12 months of therapy.

RESULTS

PTH concentrations were reduced by 13.0% to 86.7% after acute cinacalcet administration. Chronic therapy with cinacalcet was followed by a decrement in serum total calcium (10.2% at 12 months) and ionized calcium (10.1%) and an increase in serum phosphorus (20.8%), with only a modest decrement in PTH levels (5.1%). All patients had normal serum total and ionized calcium levels at 3 to 12 months of therapy. Urinary calcium decreased by 20.0% at 12 months.

CONCLUSIONS

Cinacalcet was effective in normalizing calcium and phosphorus concentrations in patients with persistent PHPT after unsuccessful parathyroidectomy.