Decreases in parathyroid gland volume after cinacalcet treatment in hemodialysis patients with secondary hyperparathyroidism.

BACKGROUND/AIM: Cinacalcet, an allosteric modulator of the calcium-sensing receptor, effectively reduces serum parathyroid hormone (PTH). It was examined whether a regression of parathyroid glands in hemodialysis patients with secondary hyperparathyroidism was induced by cinacalcet treatment. METHODS: Ultrasonography of the parathyroid glands was performed to examine the changes in the parathyroid gland volumes after cinacalcet treatment in 58 patients. RESULTS: After cinacalcet treatment, serum calcium, phosphate, alkaline phosphatase, and intact PTH significantly decreased (p < 0.0001). The total volumes of the parathyroid glands were significantly decreased 6 months after cinacalcet treatment (942 +/- 747 vs. 708 +/- 550 mm(3), p < 0.0005). There was a significant positive correlation between the parathyroid gland volumes at the start of cinacalcet treatment and the volume reduction in parathyroid glands (r = 0.716, p < 0.0001). Of the 58 patients, the total parathyroid gland volume was decreased in 42 patients and increased in 16 although the doses of cinacalcet, phosphate binders or vitamin D were not significantly different. In both groups, the intact PTH serum levels were significantly decreased after cinacalcet treatment. CONCLUSION: Cinacalcet treatment in patients with secondary hyperparathyroidism significantly reduced the total parathyroid gland volume in a short 6-month period. This study suggests that cinacalcet treatment may postpone parathyroidectomy and/or reduce cases.

Effects of Long-Term Cinacalcet Administration on Parathyroid Gland in Hemodialysis Patients with Secondary Hyperparathyroidism.

BACKGROUND/AIM: Cinacalcet, an allosteric modulator of the calcium (Ca) sensing receptor, reduces the level of parathyroid hormone (PTH) in serum as well as parathyroid gland volume following administration in hemodialysis patients with secondary hyperparathyroidism, though long-term results are yet to be reported. METHODS: Serum parameters (n = 23), together with total parathyroid gland volume (n = 18), were determined in Japanese hemodialysis patients given cinacalcet treatment for 8 years. RESULTS: Following initiation of cinacalcet therapy, levels of serum Ca, phosphate, and intact PTH were significantly decreased. Furthermore, the baseline total volume of the parathyroid gland was 1,272 mm3 (496-2,836 mm3), which was then decreased after 6 months to 796 mm3 (377-1,146 mm3) and then to 332 mm3 (175-570 mm3) after 8 years. There was significant positive correlation between parathyroid gland volume at the start of cinacalcet treatment and reduction in volume during the 8 years cinacalcet treatment. The dose of phosphate binder was significantly decreased in a time-dependent manner after 8 years of cinacalcet treatment, likely because serum phosphate showed a progressive decrease with the treatment. CONCLUSION: In the present patients, long-term treatment with cinacalcet progressively decreased the total volume of parathyroid glands, as well as levels of intact PTH and phosphate in serum in a time-dependent manner. On the contrary, cinacalcet administration did not cause secondary failure or over-suppress the transition of parathyroid gland activity to hypoparathyroid status. These results suggest that cinacalcet treatment may postpone the need for parathyroidectomy and/or reduce its use even after long-term administration for up to 8 years.

Positive correlation of serum bio-intact PTH(1-84) but not intact PTH with parathyroid gland size in hemodialysis patients.

To evaluate the usefulness of newly-developed bio-intact parathyroid hormone (Bio-PTH) assay, which measures exclusively intact PTH(1-84) molecule, serum PTH level determined by Bio-PTH assay, in comparison with second-generation intact PTH (I-PTH) assay, was examined for its correlation with parathyroid gland size. Serum PTH was determined in 46 male HD patients, together with bone formation markers bone alkaline phosphatase, intact osteocalcin, N-terminal propeptide of type I collagen, and bone resorption markers deoxypyridinoline, pyridinoline, beta-crossLaps. Maximal diameter of parathyroid gland was determined with ultrasonography as the parathyroid gland size. Serum Ca and Pi correlated significantly with parathyroid gland size rationalizing our method to define parathyroid gland size. Serum Bio-PTH was correlated significantly in a positive manner with parathyroid gland size (R = 0.308, P = 0.0474), whereas serum I-PTH did not. Furthermore, parathyroid gland size did not exhibit a significant correlation with any of bone formation markers or bone resorption markers. The lack of correlation between bone markers and parathyroid gland size in HD patients may be explained by the occurrence of refractoriness of bone to PTH. In conclusion, serum Bio-PTH assay could provide a better assay than I-PTH assay to estimate parathyroid function in HD patients, due mainly to its exclusive correlation with parathyroid gland size.

Relationship between parathyroid gland size and responsiveness to maxacalcitol therapy in patients with secondary hyperparathyroidism.

BACKGROUND: Although vitamin D has been reported to be useful in the treatment of patients with secondary hyperparathyroidism, it is not effective in some of them. The goal of this study was to see whether a relationship could be found between maxacalcitol responsiveness and parathyroid gland size. METHODS: Parathyroid gland size was measured by ultrasonography in 25 patients with secondary hyperparathyroidism [serum intact parathyroid hormone (PTH) >300 pg/ml, 58.1 +/- 2.8 years old, 15 males and 10 females], who were treated with maxacalcitol. Patients were divided into two groups according to the mean value of the maximum diameter of the glands: group S with a diameter <11.0 mm and group L with a diameter >or =11.0 mm. Between the two groups there were no significant differences in serum intact PTH, calcium or phosphate level or duration of haemodialysis. RESULTS: Mean (+/- SE) maximal diameter of detectable parathyroid glands was 11.0 +/- 0.7 mm before treatment. At 4-24 weeks after administration of maxacalcitol, intact PTH concentrations decreased significantly in group S (from 546 +/- 39 to 266 +/- 34 pg/ml at 24 weeks; P < 0.01), but did not significantly change in group L (from 481 +/- 39 to 403 +/- 49 pg/ml at 24 weeks). At 24 weeks after maxacalcitol administration, the number of detectable parathyroid glands was significantly decreased in group S (from 2.2 +/- 0.3 to 1.8 +/- 0.4; P < 0.05), but not in group L. Serum calcium increased significantly in group L (from 9.6 +/- 0.2 to 10.2 +/- 0.3 mg/dl; P < 0.05), but not in group S. There was a significant correlation between reduction in PTH and parathyroid gland size (r = -0.42, P < 0.05). CONCLUSIONS: These results indicate that the responsiveness to maxacalcitol therapy of secondary hyperparathyroidism is dependent on parathyroid gland size and that the simple measurement of maximum parathyroid gland diameter by ultrasonography may be useful for predicting responsiveness to maxacalcitol treatment.