Objective To explore value of procalcitonin (PCT) in diagnosis and differential diagnosis of medullary thyroid carcinoma.
Methods A tatal of 277 patients with thyroid nodules diagnosed by ultrasound-guided fine needle aspiration biopsy were selected, including 142 cases of benign nodules, 24 cases of medullary thyroid carcinoma, and 111 cases of non-medullary thyroid carcinoma (61 cases of papillary carcinoma, 30 cases of thyroid follicular carcinoma and 20 cases of undifferentiated carcinoma). Calcitonin (CT), carcinoembryonic antigen (CEA), thyroid stimulating hormone (TSH) and PCT were detected by luminescence method in all the patients.
Results The CT level in patients with benign nodules, non-medullary thyroid carcinoma and medullary thyroid carcinoma showed a rising trend, and the differences were statistically significant (P < 0.05 or P < 0.01). The levels of PCT in patients with medullary thyroid carcinoma, benign nodules and non-medullary thyroid carcinoma were (3.10±2.87), (0.20±0.19) and (0.14±0.10) μg/L respectively, and PCT level in patients with medullary thyroid carcinoma was significantly higher than that in patients with benign nodules and non-medullary thyroid carcinoma (P < 0.01). The levels of PCT in patients with thyroid papillary carcinoma, thyroid follicular carcinoma and undifferentiated thyroid carcinoma were (0.18±0.12), (0.07±0.04) and (0.13±0.01) μg/L respectively, and PCT level in patients with medullary thyroid carcinoma was significantly higher than that in patients with papillary thyroid carcinoma, thyroid follicular carcinoma and undifferentiated thyroid carcinoma (P < 0.01). The area under curve (AUC) of PCT in the diagnosis of medullary thyroid carcinoma was 0.978 (95%CI, 0.959 to 0.997) and P value was less than 0.001; when the cut-off value was 1.58 μg/L, the sensitivity and specificity were 99.00% and 98.78%, respectively. The AUC of PCT level in the diagnosis of non-medullary thyroid carcinoma was 0.990 (95%CI, 0.990 to 1.000, P < 0.001); when the cut-off value was 1.66 μg/L, the sensitivity and specificity of PCT in the diagnosis of medullary thyroid carcinoma were 99.10% and 99.90%, respectively.
Conclusion When screening medullary thyroid carcinoma in patients with thyroid nodules, PCT is a specific index, which can be used as a supplemented or replaced serum marker to CT. In patients with non-medullary thyroid carcinoma, PCT can also be used as an effective index to distinguish medullary thyroid carcinoma.
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