Validation, role in perioperative assessment, and clinical applications of an immunoradiometric assay for human calcitonin.
We have evaluated a new immunoradiometric assay (IRMA) for calcitonin (CT) (Medgenix, Belgium). The detection limit of immunoreactive CT (IR-CT) was 2.8 pg/ml, and plasma levels of IR-CT of 134 healthy adults (dynamic range, 2.8-1000 pg/ml) were < 19 pg/ml (median 4.1 pg/ml). Both basal and pentagastrin-stimulated IR-CT levels were < 30 pg/ml and were well separated from the levels in patients with medullary thyroid carcinoma (MTC) (46-29,000 pg/ml, n = 38). In preoperative plasma samples in five patients with C-cell hyperplasia, CT IRMA confirmed the diagnosis, although in two patients RIA failed to detect a significant increase of IR-CT. By modifying the IRMA, we could identify residual tumor tissues perioperatively in patients undergoing thyroidectomy for MTC. RIA of gel-permeation chromatography showed four IR-CT peaks, but IRMA had only three peaks, suggesting that IRMA is more specific. CT-IRMA is more specific, sensitive, robust, rapid, and reliable than RIA. In addition, neat plasma can be used directly in a single step in CT-IRMA.
Wimalawansa
S J
SJ
Department of Internal Medicine (Endocrinology), Royal Postgraduate Medical School, London, UK.
Bailey
F
F
D000328:Adult; D000368:Aged; D001800:Blood Specimen Collection; D002116:Calcitonin / Q000097:blood*; D018276:Carcinoma, Medullary / Q000097:blood* / Q000601:surgery*; D002850:Chromatography, Gel; D003276:Contraceptives, Oral; D005260:Female; D005615:Freezing; D006801:Humans; D015592:Immunoradiometric Assay / Q000379:methods; D008875:Middle Aged; D017698:Postmenopause; D017697:Premenopause; D011863:Radioimmunoassay / Q000379:methods; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D013964:Thyroid Neoplasms / Q000097:blood* / Q000601:surgery*
D003276:Contraceptives, Oral; D002116:Calcitonin