Abstract
Refining calcium test for diagnosis of medullary thyroid cancer: cutoffs, procedures and safety
C Mian, M Perrino, C Colombo, et al.
J Clin Endocrinol Metab 2014; 99: 1656–1664.
Serum calcitonin (CT) measurement is used to screen for sporadic medullary thyroid carcinoma (MTC), with stimulation using pentagastrin (Pg) sometimes necessary as a confirmatory test. However, poor Pg availability means other methods are now needed. Basal CT (bCT) and calcium-stimulated CT (Ca-sCT) are suggested as alternatives to Pg, and their performance for preoperative MTC identification was investigated in this study.
Calcium stimulation (25 mg/kg calcium gluconate) was performed in 91 prethyroidectomy patients (50 with bCT ≥10 pg/mL, 32 with bCT <10 pg/mL and 9 RET mutation carriers). CT was measured at 0, 2, 5 and 10 min post calcium infusion on the Immulite 2000 platform. There were no adverse events during calcium stimulation.
Receiver operator characteristic curves were used to compare bCT and Ca-sCT concentrations with histology, and area under curve showed similar performance with bCT (optimum cutoffs >26 pg/mL [women], >68 pg/mL [men]) and Ca-sCT (cutoffs >79 pg/mL [women], >544 pg/mL [men]) for differentiating MTC from non-MTC.
In conclusion, performance of modern CT assays may mean stimulated CT tests are unnecessary. However, if needed, high-dose calcium stimulation is reliable, potent and safe.