Endocrine Abstracts

The recent unavailability of pentagastrin (Pg) in several European Countries, prompted us to evaluate the potency and tolerability of the ‘high dose calcium test’ (Ca) in the stimulation of serum human calcitonin (hCt). We compared Pg- and Ca-stimulated hCt in 19 patients already treated for medullary thyroid cancer (MTC) in remission (n=19) or in persistence (n=13), in 18 patients with chronic thyroiditis and multinodular goiter, and in 15 healthy controls. In controls, Ct never peaked above 50 pg/ml. A response of Ct was observed in 4 cases in apparent remission without differences between the 2 tests. The hCt peak in persistent patients ranged 18–3637 for Pg and 60–2932 pg/ml for Ca tests, without significant differences even in the delta increases. The hCt peak in patients with autoimmune or nodular thyroid diseases ranged 21–942 pg/ml for Pg and 5–38 000 pg/ml for Ca tests, without significant differences. Four patients with a Ct response >100 pg/ml, have been submitted to thyroidectomy. At histology, an intrathyroidal MTC was found in 3 cases while one patient, with a Ct peak after Pg of 162 and after Ca of 599, was negative either for MTC or for C-cells hyperplasia.

The number, intensity and duration of side effects were significantly lower during Ca test, being the feeling of warmth the most frequent discomfort.

In conclusion, this study demonstrated that high dose Ca test has a similar or higher potency than Pg test. In addition, Ca test was well tolerated and highly preferred by patients. These data, associated with the lower cost of Ca and its worldwide availability, indicate that the high-dose calcium is the test of choice for the pre-surgical diagnosis of MTC and for the follow up. Ongoing studies will identify the cut-off point to use for this test in the pre-surgical identification of MTC.