Basal and Calcium-Stimulated Procalcitonin for the Diagnosis of Medullary Thyroid Cancers: Lights and Shadows

Abstract

BackgroundProcalcitonin (proCt) was recently proposed as an alternative or in addition to calcitonin (Ct) in medullary thyroid cancer (MTC) diagnostics.MethodsSerum basal Ct (bCt) and proCt (bproCt) levels were measured before surgery from a consecutive series of patients with (n=43) and without (n=75) MTC, retrospectively collected in Padua. Serum bproCt, bCt and stimulated proCt and Ct (sproCt and sCt) were measured in another consecutive series of 33 patients seen at three tertiary-level institutions undergoing a calcium stimulation test prior to surgery, 20 of them with a final diagnosis of MTC, and 13 with non-MTC nodular disease.ResultsMedian bproCt levels were higher in MTC than in non-MTC. A positive correlation was found for bproCt with bCt (P<0.01, R2 = 0.75), and with tumor size (P<0.01, R2 = 0.39). The cut-off for bproCt differentiating between MTC and non-MTC patients was >0.07 ng/ml (sensitivity: 85.7%, specificity: 98.9%, positive predictive value [PPV]: 98.2%, negative predictive value [NPV]: 90.6%, P<0.01). While bproCt was >0.07 ng/ml in 38/39 (97.4%) patients with MTC >10 mm, it was above said cut-off only in 15/23 (65.2%) patients with tumors ≤10 mm. A sproCt >0.19 ng/ml was able to identify MTC [sensitivity: 90.0%, specificity:100.0%, PPV: 100.0%, NPV: 86.7% (P<0.01)].ConclusionsOur data suggest that bproCt can be a good adjunct to Ct for MTC diagnostic purposes. In consideration of its high specificity, it can be used in combination with Ct in MTC diagnostics, particularly in the case of mildly elevated basal Ct levels.

Diagnostic Utility of Procalcitonin for Sporadic Medullary Thyroid Carcinoma in Patients with Nodular Disease and Mild or Moderate Hypercalcitoninemia

“…The same was observed in the study by Censi et al. 5 in which all patients without MTC exhibited Ctn<30 ng/ml and 94.3% had<20 ng/ml.…”

“…In our study, 5/9 patients without MTC and with Ctn between 20 and 50 ng/ml also had pro-Ctn>0.1 ng/ml. In contrast, none of the patients without MTC with these Ctn concentrations had elevated pro-Ctn in the series of Giovanella et al 8 9 10 and Censi et al 5 .…”

“…Few studies have evaluated pro-Ctn specifically for the diagnosis of sporadic MTC in patients with nodular thyroid disease [5,8,9]. For the reasons mentioned above, pro-Ctn in this situation would be useful especially for subjects with hypercalcitoninemia < 100 pg/ ml [1].…”

“…For the reasons mentioned above, pro-Ctn in this situation would be useful especially for subjects with hypercalcitoninemia < 100 pg/ ml [1]. A small number of patients with nodular disease and mild or moderate hypercalcitoninemia have so far been evaluated using pro-Ctn measurement [5,8,9].…”

“…On the other hand, MTC is very likely in patients with thyroid nodules and basal Ctn > 100 pg/ ml in the absence of any other known cause (such as chronic renal failure, another secreting tumor). In addition, at these Ctn concentrations, pro-Ctn is almost always elevated [2][3][4][5]. Thus, to screen for sporadic MTC, pro-Ctn would be more useful in patients with basal Ctn > 10 pg/ml but < 100 pg/ml [1].…”