Response of secondary hyperparathyroidism to cinacalcet depends on parathyroid size.
OBJECTIVE
Several reports have indicated that the measurement of parathyroid gland size assists the management of patients with secondary hyperparathyroidism. This study examined whether parathyroid gland enlargement influenced the response of secondary hyperparathyroidism to cinacalcet.


METHODS
Clinically stable hemodialysis patients with secondary hyperparathyroidism that was resistant to conventional treatment received cinacalcet for 6 months. Based on the parathyroid gland size measured by ultrasonography, the patients were divided into group S (gland <500 mm(3)) and group L (gland >or=500 mm(3)). Serum levels of intact parathyroid hormone (intact PTH), bone-specific alkaline phosphatase, osteocalcin, and cross-linked N-terminal telopeptide of type 1 collagen were measured over time.


RESULTS
Twenty-four patients completed the study. In group S, all markers of bone metabolism and intact PTH were significantly decreased after 3 months of cinacalcet treatment. In contrast, there were no significant changes of these parameters, except for intact PTH, after 3 months in group L. After 6 months of cinacalcet treatment, however, all of the markers of bone metabolism were significantly decreased in both groups.


CONCLUSIONS
The response to cinacalcet differed between groups S and L. Thus, the presence of parathyroid enlargement (nodular hyperplasia) may delay the response of secondary hyperparathyroidism to cinacalcet.
Hirai
Takayuki
T
Department of Internal Medicine, Hakuai Clinic, Kure City, Japan.
Nakashima
Ayumu
A
Takasugi
Norihisa
N
Yorioka
Noriaki
N
D000069449:Cinacalcet; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D008297:Male; D009281:Naphthalenes / Q000627:therapeutic use*; D009929:Organ Size; D010280:Parathyroid Glands / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D014463:Ultrasonography
D009281:Naphthalenes; D000069449:Cinacalcet