A new immunoradiometric assay (IRMA) system for thyroglobulin measurement in the follow-up of thyroid cancer patients

Abstract

A new commercially available kit for thyroglobulin (Tg) measurement [immunoradiometric assay (IRMA) system based on monoclonal antibodies] was used in 479 patients with thyroid carcinoma. The effective working range was 1 ng/ml, and results were strongly correlated with our homemade radioimmunoassay (RIA). This IRMA method is less susceptible to interferences of auto-antibodies than our RIA. During thyroxine (T4) treatment, the Tg level was undetectable in 98% of patients after total thyroid ablation, in 91% after total thyroidectomy and in 42% after lobectomy only. In this situation, Tg was found in all patients with large metastases and in 88% of those with small metastases. Following T4 withdrawal, Tg was detectable in all patients with neoplastic disease and in 13% of those in complete remission after total thyroid ablation. In conclusion, Tg measured with this IRMA method appears to be a reliable marker of differentiated thyroid carcinoma.

Does 131I Radioactivity Interfere with Thyroglobulin Measurement in Patients Undergoing Radioactive Iodine Therapy with Recombinant Human TSH?

“…IRMA is a reliable method for the measurement of Tg in the follow-up of DTC after total thyroidectomy [1]. Our study evaluated whether 131 I administration interferes with Tg I group, which shows no significant change in the Tg value between days 2 and 32. b The 1,110 MBq 131 I group, which shows no significant change in the Tg value between days 2 and 32 measurement using IRMA because of the relatively high energy of 131 I compared to 125 I. Usage of rhTSH for stimulation of TSH is becoming easy because of insurance coverage in Korea.…”

“…Immunoradiometric assay (IRMA) is widely used for the measurement of thyroglobulin (Tg) levels [1]. Despite debates on the discordance between commercial assay kits [2][3][4][5][6], highsensitivity human Tg IRMA can detect serum Tg concentrations of 0.2 ng/ml, and serum Tg concentrations <0.2 ng/ml are used to indicate complete remission [7].…”

Serum Tg—A Sensitive Marker of Thyroid Abnormalities and Iodine Deficiency in Epidemiological Studies

“…Serum Tg and TSH were analyzed with immunoluminometric assays (LUMITEST, BRAHMS, Berlin, Germany) using a Stratec autoanalyzer (STRATEC-BIOMEDICAL SYSTEM AG, Birkenfeld, Germany). The Tg assay had an effective working range of 1-500 g/liter (23). All assays included control samples at 3 levels at the start and end of each run.…”

Serum thyroglobulin determination in the follow-up of patients with differentiated thyroid carcinoma

“…Functional sensitivity was 1±2 ng/ml and correlation with previous RIAs was excellent in sera in which there was no interference in the assay. Since 1994, the functional sensitivity of IRMA methods has improved to less than 1 ng/ml (4,5). However, the clinical signi®cance of some of these highly sensitive IRMAs becomes questionable either because intra-and interassay precision is not stable enough from batch to batch, or because non-speci®c effects in the assay system lead to a large number of detectable, although low, Tg values that do not correspond to the clinical history or actual situation of the patients.…”