Safety of calcitonin stimulation tests with calcium

Medullary thyroid carcinoma (MTC) is an aggressive form of thyroid cancer. Early detection is essential because only complete resection of the thyroid tumor and any local metastases can cure MTC. Calcitonin (CT) is a marker used for diagnosis of MTC. In controversial cases of slightly elevated CT levels, stimulation tests have shown their utility, but their safety should also be taken into account.

Our aim is to present our own experience regarding the safety of CT stimulating tests.

We applied a specific protocol of calcium stimulation test in 176 patients after informed consent (115 women with a median age of 46 years, range 21-79; 61 men with a median age of 54 years, range 22-78). We recorded the side effects and a further analysis was performed.

The most frequent side effects noted were hot flashes in 159 out of 176 patients (90.34%), followed by dysgeusia (32/176) and bradycardia (10/176). Severe bradycardia was reported in only one patient (0.568%), which was rapidly reversible. There was no correlation between patients' age, weight, height, body mass index, basal CT or peak stimulated CT, and grade of severity, but men were more likely to develop cardiovascular side effects than women, namely, bradycardia, tachycardia, ventricular or atrial extrasystoles, hypertension, hypotension, or angina (p = 0.024), with an odds ratio of 2.94 (CI: 1.11-7.76). We recommend thyroid surgery in all women with sCT above 285 pg/ml.

The calcium stimulation test is well tolerated, with few adverse reactions. The test should be performed with appropriate precautions (i.e., ECG monitoring during and after the test) to minimize the possibility of a serious event.