Detektion okkulter medullärer Schilddrüsenkarzinome bei Patienten eineruniversitären Schilddrüsen-Ambulanz: Diagnostischer Wert von Calcitonin-Screening, Pentagastrintest und Gastrinrezeptorszintigraphie

In patients with medullary thyroid carcinoma or neoplastic c-cell hyperplasia extremely elevated basal calcitonin levels are known. The aim of this study was to analyze the value of a basal calcitonin screening for early diagnosis of medullary thyroid carcinoma or neoplastic c-cell hyperplasia in a large population of clinically inconspicuous individuals. The diagnostic value of elevated calcitonin levels after Pentagastrin stimulation test, the use of preoperative diagnostic ultrasound, and CCK-2-receptor scintigraphy with 111Indium-D-Glu1-sulfated Minigastrin in terms of predictive values were also evaluated. Additionally the correlation between the pathologic tracer enhancement, the calcitonin levels and the final histological diagnosis was analysed. In conclusion we re-evaluated our current diagnostic algorithm. A total of 4858 patients over a period of 47 months were reviewed. All of them underwent testing of basal calcitonin level in serum blood and were clinically examined in the thyroid ambulance of a medicine university hospital. 300 patients off all had increased calcitonin levels considering normal cut off values < 4,6 pg/ml in women and < 11,5 pg/ml in men. 259 of them underwent a stimulation test with Pentagastrin. 1,1% of these patients had also elevated stimulated calcitonin levels >100,0 pg/ml. Patients having stimulated calcitonin levels less than 100,0 pg/ml were advised to control the calcitonin level once a year. 34 of 55 patients with suspicious calcitonin levels and prior to thyroidectomy had additional CCK-2 receptor scintigraphy with 111Indium-D-Glu1 sulfated Minigastrin. Finally 32 patients underwent surgery whereof two had a medullary thyroid carcinoma. The prevalence to suffer from medullary thyroid carcinoma in this population was 0,04%. Both patients with medullary thyroid carcinoma had an advanced basal and the stimulated calcitonin level compared with patients with c-cell hyperplasia or a thyroid without pathological findings. For differential diagnosis of thyroid carcinoma, neoplastic, nodulary or diffuse ccell hyperplasia or an inconspicuous thyroid the calcitonin test (basal and stimulated) by itself can not be used. 104 On the basis of the results of the present study it is very important using a diagnostic cascade. First basal calcitonin level should be checked in blood serum. In case of extensive values (dependance on used assay), a stimulation test with Pentagastrin should be added. Only a stimulated value >100,0 pg/ml presumes the existence of a medullary thyroid carcinoma or a neoplastic c-cell hyperplasia. The extreme value of stimulated calcitonin of 100,0 pg/ml appears to be correct, because after thyroidectomy we detected more pathological thyroids (CA, nodulary-, diffuse C-cell hyperplasie), than thyroids without pathological findings. Indication for thyroidectomy in these patients is only seen in pathologically elevated calcitonin levels after stimulation. Scintigraphy with 111Indium-D-Glu1 sulfated Minigastrin is inadequate for primary diagnosis of medullary thyroid carcinoma. The more it is important in postoperative clinical monitoring, detecting recurrent disease or metastases, or in cases of persistent increased calcitonin levels.