Primary Hyperparathyroidism: Short-term Calcimimetics Treatment - Relevance for Parathyroid Surgery Decisions?

The study evaluates if short-term treatment with calcimimetics may be used for patients with PHPT as a relevant guide in the decision of when to choose parathyroid surgery, by predicting the outcome of surgical treatment.

120 ± 2 patients with primary hyperparathyroidism scheduled for parathyroid surgery will be included in the study after informed consent and will receive study medication with cinacalcet, Mimpara® 30 mgx1 for four weeks. In case of persistent hypercalcemia after two weeks of treatment with Mimpara® 30 mgx1, the dosage of Mimpara® will be increased to 60 mg daily. During the study drug treatment period, the patients will be followed closely at least once a week with clinical monitoring and control of serum ionized calcium, given the risk of side effects and hypocalcemia. If the concentration of ionized calcium in serum will decrease to a subnormal level (<1.15 mmol/l), the Mimpara® treatment will be discontinued temporarily and only reinserted in a lower dose (30 mg x 1) if the concentration of ionized calcium raises over 1.33 mmol/l. The size of the cohort has been decided after power estimations based on the results in study part A. Both groups will go through the test panel of self-rating scales described above at four occasions (Figure).

The Outcome to be registered are the changes from baseline to the end of the study medication period compared to the changes postoperatively, thus the changes between the Visit 2 to Visit 6 and the changes between Visit 2 and Visit 7 and Visit 8 respektively.

Assessments and Procedures Visit 1: Clinical examination (general condition, neck, blood pressure, cor et pulm). Screening of patients with primary hyperparathyroidism scheduled for parathyroid surgery. Patient that fulfills inclusion and exclusion criteria will be asked to participate in the study.

Visit 2: Informed consent is signed. Test panel of self rating scales (Quality of Life Questionnaire-Core 30 (QLQ-C30), Positive States of Mind (PSOM )and Hospital Anxiety and Depression scale (HAD), cognitive test (Montreal cognitive assessment (MoCA-Test)) and muscle strength (Timed stand test). Blood samples are drawn within 2 weeks before and analyzed for: parathyroid hormone (p-PTH), s-ionized calcium, p-total calcium, p-albumin, p-creatinine, p-phosphate, s-25-OH-D-vitamin and p-TSH. Initiation of treatment with Mimpara® 30 mg x 1. Clinical examination (general condition, blood pressure). For fertile women, a pregnancy test is demanded before enrollment.