title: Serum calcitonin negative medullary thyroid carcinoma.
abstract: BACKGROUND
  Medullary thyroid carcinomas (MTC) constitute about 5 to 7% of thyroid neoplasms. They originate from parafollicular C cells which produce Calcitonin, a hormone which has an impact on calcium metabolism and represents the biochemical activity of MTC. In rare cases pre-operative serum calcitonin can be negative.
  
  
  METHODS
  We report on a 73-year-old female patient with a rare case of a serum calcitonin negative medullary thyroid carcinoma who suffered fulminant post-operative course and died of multiple metastasis.
  
  
  CONCLUSIONS
  This case shows that in very rare cases MTCs do not secrete calcitonin making diagnosis and tumour follow-up difficult. To this date, only few reports describing this combination of circumstances were found in the English literature.
authors.affiliation: Department of General and Visceral Surgery, Augusta Krankenanstalt, Academic Teaching Hospital, Ruhr-University Bochum, Germany. michael.sand@ruhr-uni-bochum.de
authors.forename: Michael
authors.initials: M
authors.lastname: Sand
authors.forename: Marcos
authors.initials: M
authors.lastname: Gelos
authors.forename: Daniel
authors.initials: D
authors.lastname: Sand
authors.forename: Falk G
authors.initials: FG
authors.lastname: Bechara
authors.forename: Gerd
authors.initials: G
authors.lastname: Bonhag
authors.forename: Ellen
authors.initials: E
authors.lastname: Welsing
authors.forename: Benno
authors.initials: B
authors.lastname: Mann