title: Routine calcitonin measurement in nodular thyroid disease management: is it worthwhile?
abstract: OBJECTIVE
  To evaluate the diagnostic accuracy of routine calcitonin measurement in patients with nodular thyroid disease.
  
  
  METHODS
  Consecutive patients with nodular thyroid disease (n = 640) were studied. Serum calcitonin levels were measured under basal conditions, and when basal values were between 10-100 pg/mL, testing was repeated after pentagastrin (PG) stimulation. Patients with previously diagnosed or familial medullary thyroid cancer (MTC) were excluded. Patients were operated on when basal or stimulated calcitonin >100 pg/mL or when other surgical indications were present.
  
  
  RESULTS
  Four cases of MTC were identified. MTC was diagnosed in 75% of patients with basal calcitonin >100 pg/mL. One out of 11 patients with basal calcitonin between 10-100 pg/mL was diagnosed with MTC. PG stimulation resulted in elevation in 4 cases, where 1 case was diagnosed with MTC. Positive predictive value for basal calcitonin levels in the preoperative diagnosis of MTC was 5% for values between 10-100 pg/mL and 100% for values >100 pg/mL. Possible reasons for false positivity were papillary thyroid cancer in 17%, renal insufficiency in 8.3%, Hashimoto thyroiditis in 17% and β-blocker use in 33%. Positive predictive value for the PG test (>100 pg/mL) was 25% in the entire series. The cost of adding calcitonin measurement (±PG stimulation) to the preoperative work-up, resulted in €912.68 per MTC patient to detect the disease.
  
  
  CONCLUSIONS
  Basal calcitonin measurement together with PG stimulation in cases of basal calcitonin >10 pg/mL detects MTC in 0.62% of patients with nodular thyroid disease.
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Yigit
authors.initials: Y
authors.lastname: Turk
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Ozer
authors.initials: O
authors.lastname: Makay
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Ozdemir
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Gozde
authors.initials: G
authors.lastname: Ertunc
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Batuhan
authors.initials: B
authors.lastname: Demir
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Gokhan
authors.initials: G
authors.lastname: Icoz
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Mahir
authors.initials: M
authors.lastname: Akyildiz
authors.affiliation: Division of Endocrine Surgery, Department of General Surgery, Ege University Hospital, Izmir, Turkey.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Yilmaz
keywords: Calcitonin; Cytology; Thyroid nodule