Routine Measurement of Serum Calcitonin Concentration is Useful in Early Detection of Medullary Thyroid Carcinoma Among Patients with Nodular Thyroid Disease / 대한내분비학회지

ABSTRACT

BACKGROUND: Serum calcitonin is a sensitive and specific marker for diagnosis of medullary thyroid carcinoma (MTC) and its determination leads to accurate preoperative diagnosis and gives chances of definite cure. However, since many non-MTC diseases are also associated with calcitonin elevation, its significance in patients with mild or moderately elevated basal serum calcitonin levels is not clear. Furthermore, the normal value of calcitonin using immunoradiometric assay (IRMA) kit has not so far been definitely ascertained. This study is aimed at assessing the clinical significance of routine measurement of serum basal calcitonin concentration in nodular thyroid disease patients and evaluating the pentagastrin stimulation test in case of mild or moderate elevation of basal calcitonin level. We also measured serum calcitonin value in 408 normal individuals. METHODS: The basal serum calcitonin concentrations using a commercial IRMA kit (Medgenix CT-U.S.-IRMA) were measured in 818 patients with nodular thyroid disease (average age 45 years with a range from 13 to 82 years; 125 males and 693 females) who visited thyroid clinics in Samsung Medical Center between June 1997 and December 1998. Serum concentrations of T3, T4, TSH and thyroid autoantibodies were measured and ultrasonography of thyroid and thyroid scan using 131I or 99mTc-pertechnetate were performed in all patients. We also studied 408 healthy subjects without any thyroid disease (average age 48 years with a range from 20 to 86 years; 224 females). RESULTS: The calcitonin value in normal subjects was found to range from 0 to 13 pg/mL, and it was shown that men had higher calcitonin level than women (p 10pg/mL) in nodular thyroid disease was 1.71% (14/818), and the incidence of MTC was 0.73% (6/818) in this study. MTC was found in all patients with basal serum calcitonin levels more than 100 pg/mL. Pentagastrin stimulation test was also required to diagnose MTC in patients with basal serum calcitonin levels between 30 and 100pg/mL. The calcitonin concentration stimulated by pentagastrin increased more than 400pg/mL or more than 3.8 times of basal concentration. It was possible to diagnose MTC with fine needle aspiration and cytology in only one case out of six patients with MTC. CONCLUSION: Fine needle aspiration and cytology in diagnosing MTC was not sensitive and not devoid of false positive results. We confirmed that serum calcitonin measurement was very useful means for the preoperative diagnosis of unsuspected MTC. Pentagastrin stimulation test may be a reliable means of evaluation in nodular thyroid disease patients with mild or moderate elevation of basal calcitonin level. We recommend routine measurement of serum calcitonin concentration in patients with nodular thyroid disease.