[Clinical evaluation of a new thyroglobulin immunoradiometric assay in the follow-up of differentiated thyroid carcinoma].
OBJECTIVE
Formal and clinical comparison of a new 3 (rd) -generation-Tg-IRMA (3-G-IRMA; Dynotest Tg-plus) with a conventional Tg-IRMA (3-G-IRMA; SELco Tg-assay) for patients with differentiated thyroid carcinoma. In addition we evaluated, if thyroglobulin (Tg) levels above a specific threshold concentration indicate the need for further investigations for residual disease.


METHODS
Tg concentration of 105 sera of 93 consecutive patients with a differentiated thyroid cancer was determined with both assays and compared at different cut-off values (Dynotest Tg-plus: 0.2, 1, 2 ng/ml; SELco Tg-assay: 0.5, 1, 2 ng/ml) with the clinical results in respect to the corresponding TSH concentration.


RESULTS
Tg concentration did not show any significant difference (SELco Tg-assay 0.5 ng/ml, Dynotest Tg-plus 0.2 ng/ml). The Tg-values of both assays correlated with 97%. However, correlation of recovery in both assays was small (40%). The sensitivities and specificities of both assays at different cut-offs and TSH values did not reveal significant differences. In patients with TSH concentration > 30 micro U/ml the functional assay sensitivity was superior to arbitrary cut-offs in the decision to start further evaluations.


CONCLUSIONS
In our study neither formal nor clinical significant differences between two Tg-assays were found. In a hypothyroid patient (TSH > 30 micro U/ml, Tg concentration exceeding the functional assay sensitivity) further investigations for residual disease are warranted. Higher thresholds are of limited value, due to an unacceptably high rate of false negative results.
Sahlmann
C-O
CO
Zentrum Radiologie, Abteilung Nuklearmedizin, Georg-August-Universität Göttingen, Robert-Koch-Str. 40, 37075 Göttingen. csahlmann@med.uni-goettingen.de
Schreivogel
I
I
Angerstein
C
C
Siefker
U
U
Lehmann
K
K
Altenvoerde
G
G
Hüfner
M
M
Meller
J
J
D002277:Carcinoma / Q000097:blood* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D009362:Neoplasm Metastasis; D011863:Radioimmunoassay / Q000379:methods; D015203:Reproducibility of Results; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood / Q000473:pathology; D013972:Thyrotropin / Q000097:blood; D013997:Time Factors
D013972:Thyrotropin; D013954:Thyroglobulin
Klinischer Stellenwert eines neuen Thyreoglobulin-immunoradiometrischen Assays in der Nachsorge des differenzierten Schilddrüsenkarzinoms.