IV calcitriol treatment in patients with early-stage secondary hyperparathyroidism prevents parathyroid (PT) gland growth, researchers report.

Masatomo Taniguchi, MD, of the Graduate School of Medical Sciences at Kyushu University in Fukuoka, Japan, and collaborators randomized patients with mild hyperparathyroidism to receive either daily oral calcitriol (33 patients) or IV calcitriol (27 patients) over a 12-month period.

Calcitriol was modulated to keep serum intact parathyroid hormone (PTH) between 100 and 150 pg/mL. The mean age of the patients was 66 years in the oral calcitriol group and 59 years in the IV calcitriol group, but the difference was not significant.

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Both groups had comparable declines in serum PTH and similar increases in serum calcium, the authors reported in Nephrology Dialysis Transplantation (2008;23:3662-3669). As assessed by ultrasonography, the maximum PT volume increased significantly from 49 to 101 mm3 in the oral calcitriol group. Patients in the IV calcitriol group, however, experienced a nonsignificant decline in maximum volume from 96 to 89 mm3.

Total gland volume increased from 65 to 134 mm3 in the oral calcitriol recipients but declined nonsignificantly from 150 to 135 mm3 in the IV calcitriol arm. The changes of both maximum and total gland volume were significantly larger in the oral calcitriol than the IV calcitriol group.

When ultrasonography demonstrates PT enlargement in the presence of mild secondary hyperparathyroidism, IV vitamin D therapy should be started at an early stage, the authors concluded.