Can procalcitonin be useful for medullary thyroid cancer?

Calcitonin, the best known marker for medullary thyroid cancer (MTC), has several laboratory limitations which limit its use in the routines of non-specialized laboratories. Procalcitonin, the precursor of calcitonin, is free from these drawbacks. The aim of this study was to compare calcitonin and procalcitonin levels in MTC patients with active disease or in remission, and in patients with non-toxic nodular goiter (NTNG).

Forty-three serum samples, obtained from 40 patients (6 MTC active disease patients, 23 MTC patients in remission, and 11 NTNG patients), were tested for calcitonin and procalcitonin levels. The levels of both markers were measured in 2 MTC patients with active disease before and after surgery. One was re-operated due to neck relapse, the other one due to liver metastases.

Both procalcitonin and calcitonin levels were considerably higher in all MTC patients with the active disease. In two re-operated patients, the levels of both markers decreased after surgery but remained above the reference range. In the remission group of MTC patients, 18 had both markers within the reference range, 2 had slightly elevated calcitonin, and 3 patients exhibited both markers slightly increased. In the NTNG group, all but one patient had normal procalcitonin and calcitonin levels. Analysis revealed a significant correlation between procalcitonin and calcitonin levels (r = 0.7383; p < 0.0001).

Procalcitonin has a similar distribution of values as calcitonin and may be used for evaluation of MTC status in some situations when accurate CT estimation is not achievable.