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Predictive value of pentagastrin test for preoperative differential diagnosis between C‐cell hyperplasia and medullary thyroid carcinoma in patients with moderately elevated basal calcitonin levels
Author(s) -
Milone F.,
Ramundo V.,
Chiofalo M. G.,
Severino R.,
Paciolla I.,
Pezzullo L.,
Lombardi G.,
Colao A.,
Faggiano A.
Publication year - 2010
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.2009.03759.x
Subject(s) - pentagastrin , medicine , endocrinology , calcitonin , medullary cavity , thyroid carcinoma , basal (medicine) , differential diagnosis , hyperplasia , medullary carcinoma , predictive value , thyroid , pathology , stomach , gastric acid , insulin
Summary Background and Objectives Medullary thyroid carcinoma (MTC) is a calcitonin (CT)‐secreting neuroendocrine tumour originating from thyroid C cells. Serum CT concentrations are helpful in the early detection of MTC, while it is still unclear whether they can be used also for the differential diagnosis between MTC and C‐cell hyperplasia (CCH), a precancerous condition in familial MTCs but with unclear clinical significance in sporadic MTCs. Nowadays, surgery is recommended in all patients with basal or pentagastrin (PG)‐stimulated CT value of 100 pg/ml or more, without discriminating if they are affected with MTC or CCH only. The objective of this study was to investigate the utility of the PG test for CT in distinguishing CCH from MTC before surgery. Patients and Methods Sixteen of 20 patients with thyroid nodules and basal CT levels between 15 and 100 ng/l had a positive PG test (>100 ng/l PG CT peak) and form the basis of the data analysis. A diagnosis of MTC was histologically proved on surgical samples in seven patients and of CCH in nine other patients. Four patients with neither FNAB nor PG test consistent with a diagnosis of MTC did not undergo thyroidectomy. Results A peak of CT of 275 ng/l after PG was able to significantly distinguish patients with MTC from patients with CCH, with 100% sensitivity and 89% specificity ( P = 0·002). PG‐stimulated calcitonin levels >275 ng/l had a positive predictive value (PPV) value for diagnosis of MTC of 100%, and PG‐stimulated calcitonin levels <275 had a PPV for the diagnosis of CCH of 89%. Conclusions A CT cut‐off after PG of 275 ng/l is suggested to be highly predictive in distinguishing CCH from MTC before surgery, and this may be helpful in selecting patients for thyroid surgery.