Calcitonin and procalcitonin in patients with medullary thyroid cancer or bacterial infection.
To evaluate procalcitonin (PCT) utility as a marker of medullary thyroid cancer (MTC). Calcitonin (CT) and PCT levels were measured in MTC patients and patients with serious bacterial infections. 70 patients were enrolled in the study: 6 MTC active patients: 4 with disseminated, unreoperable disease and 2 re-operated patients, in whom markers were checked before and after surgery; 23 MTC patients in remission after radical surgery; 11 non-toxic nodular goiter (NTNG) patients; 30 patients with severe, bacterial infection or sepsis. All MTC active patients had greatly elevated CT and PCT levels. In two re-operated patients, marker levels decreased but were still above the reference range. In 15 MTC patients in remission, the levels of either marker were not increased. Both markers were slightly increased in 3 patients in this group, while CT was elevated in 5 patients. In all but 1 patient in the NTNG group, both marker levels were not elevated. Among patients with bacterial infection, PCT and CT levels showed no increase in 8 patients, both markers were elevated in 10 patients, and an increase of PCT levels was seen in 10 patients while of CT only in 2 patients. Correlations between CT and PCT values were very strong in MTC patients (r = 0.95; p = 0.004 for active MTC, r = 0.60; p = 0.002 for MTC patients in remission) and in patients with NTNG (r = 0.77; p = 0.02). In patients with infection, both parameters were completely independent (r = 0.002; p = 0.99). PCT measurement could be an alternative to CT measurement for evaluation of MTC status.