title: Identification of occult metastases of medullary thyroid carcinoma by pentagastrin-stimulated intravenous calcitonin sampling followed by targeted surgery.
abstract: BACKGROUND
  High calcitonin (CT) serum levels suggest metastatic spread in medullary thyroid carcinoma (MTC) after thyroidectomy. In limited disease stages, however, morphological investigations including ultrasound, magnetic resonance imaging (MRI) and 18F-FDG positron emission tomography ([18F]FDG-PET) may often fail to identify exact tumour sites.
  
  
  OBJECTIVE
  The aim of the present study was to establish an improved strategy to identify small cervical tumours by combining pentagastrin stimulation with bilateral cervical intravenous CT sampling followed by high-resolution ultrasound.
  
  
  METHODS
  Six MTC patients were examined, of whom five patients already had bilateral neck dissection. Five patients had sporadic MTC, and one patient suffered from MEN2a.
  
  
  RESULTS
  Retrospective analysis of all patients revealed a highly sensitive positive correlation between an early calcitonin peak (20-40 s after pentagastrin injection) and site of cervical tumour affection. Postinterventional ultrasound examination of the affected regions of the neck revealed suspicious presence; in some cases small lymph nodes of less than 1 cm in size were then surgically excised. On histology, small tumours could be identified in four patients. Postsurgical examination revealed a clear decline of basal serum calcitonin levels in four patients (between -41% and -100%). In two patients CT normalized to baseline levels (< 10 pg/ml) and in another two patients CT rendered to near normal (14 and 17 pg/ml).
  
  
  CONCLUSIONS
  Pentagastrin stimulation-based intravenous catheter sampling may be beneficial in the diagnostic work-up of MTC after thyroidectomy. Our data show that an early calcitonin peak (20-40 s after administration of pentagastrin) helps to identify tumour-affected regions.
authors.affiliation: Department of Endocrinology, Diabetes and Rheumatology, University Hospital Dusselsorf, Germany. schottmt@uni-duesseldorf.de
authors.forename: Matthias
authors.initials: M
authors.lastname: Schott
authors.forename: Holger S
authors.initials: HS
authors.lastname: Willenberg
authors.forename: Cornelia
authors.initials: C
authors.lastname: Sagert
authors.forename: Thi-Bang-Tam
authors.initials: TB
authors.lastname: Nguyen
authors.forename: Sven
authors.initials: S
authors.lastname: Schinner
authors.forename: Mathias
authors.initials: M
authors.lastname: Cohnen
authors.forename: Kenko
authors.initials: K
authors.lastname: Cupisti
authors.forename: Claus F
authors.initials: CF
authors.lastname: Eisenberger
authors.forename: Wolfram T
authors.initials: WT
authors.lastname: Knoefel
authors.forename: Werner A
authors.initials: WA
authors.lastname: Scherbaum
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000097:blood*; D002116:Calcitonin / Q000097:blood*; D018276:Carcinoma, Medullary / Q000556:secondary* / Q000601:surgery; D005260:Female; D006801:Humans; D049449:Luminescence; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D018813:Multiple Endocrine Neoplasia Type 2a / Q000556:secondary / Q000628:therapy; D018365:Neoplasm, Residual / Q000175:diagnosis* / Q000601:surgery; D010418:Pentagastrin; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000556:secondary* / Q000601:surgery; D013965:Thyroidectomy
chemical_list: D014408:Biomarkers, Tumor; D002116:Calcitonin; D010418:Pentagastrin