Endocrine Abstracts

Objective: To assess the regulation of parathormone (PTH) and serum calcium (s-Ca) in patients, on follow-up over a long time period of four years, who have primary hyperparathyroidism (pHPT) and whose condition is non-operable or who are not willing to undergo surgery.

Methods: Initially, 17 patients with documented pHPT were recruited and treated with calcimimetic cinacalcet at a dose calculated according to s-Ca levels (≤11 mg/dl or >11 mg/dl), amounting to 30–60 mg/daily (n=8) and 60–90 mg/daily (n=9). All the patients but four underwent PTH and s-Ca monitoring, firstly after 3 months and then every 6 months, together with monitoring of s-phosphorus, 25-hydroxy-vitamin D [25(OH)D] levels, and a yearly bone mineral density (BMD) check. No patients were taking other drugs, except for cholecalciferol compounds. To compensate for the small number of patients, we analyzed both mean and median values and parametric and non-parametric analysis was performed.

Results: Gr1 (n=7) and Gr2 (n=6) were matched by age 66±9.2 yr vs. 69.5±6.5 yr. S-Ca levels were statistically significantly (ss) higher at baseline in Gr1 (11.3±0.2 mg/dl) than in Gr2 (10.7±0.2 mg/dl; P<0.002). PTH levels were higher, though not ss, in Gr1 (262.8±114.9 pg/ml) than in Gr2 (180.5±17.1 pg/ml). A steep and rapid reduction of PTH was observed in Gr1 at month 3 (M3) resulting in a lower mean and median vs Gr2 for this time point as well as for the following assessments. After M24 and until M48, mean and median values for PTH were close for the 2 groups (M24: 126.6±31.2 pg/ml vs. 118±33.3 pg/ml; M48:95.3±22 pg/ml vs.100.3±9 pg/ml). A consistently increasing level of 25 (OH) D was noted throughout the study in both groups, peaking at M36. No difference in the z-score between both groups was registered. BMI tendentially decreased in both groups.

Epicrisis: Cinacalcet was effective in controlling s-Ca and reducing PTH levels in patients with moderate and severe pHPT. The effect on PTH is characterized by fluctuations and is apparently dose- and time-dependent since stabilization was achieved following several years of treatment. The steady increase of Vit D3 levels could also have contributed to PTH moderation. These results, though numerically limited, should be considered when long-term medical treatment of pHPT is applied.