Development of a sensitive and specific quantitative reverse transcription-polymerase chain reaction assay for blood thyroglobulin messenger ribonucleic acid in the follow-up of patients with differentiated thyroid carcinoma.
BACKGROUND
Serum thyroglobulin is a sensitive tumor marker in the follow-up of patients with differentiated thyroid carcinoma (DTC), but the presence of endogenous anti-thyroglobulin antibodies (TgAb) can interfere on its measurement. To prevent interference by TgAb, several investigators have tried to quantify blood mRNA Tg by real-time RT-PCR, but the results have been variable, not reporting a correlation between mRNA Tg and the presence of metastases.


OBJECTIVE
The aim of the study was to evaluate the development of a sensitive and specific quantitative RT-PCR assay for blood mRNA Tg in the follow-up of patients with DTC.


METHODS
An assay employing primers located in a region not affected by alternative splicing or single nucleotide polymorphisms was developed to study 104 DTC patients (13 of 104 with positive TgAb).


RESULTS
The assay is specific for thyroid tissue because we found mRNA Tg expression in normal thyroid tissue, but we did not find any mRNA Tg expression in any extrathyroidal tissues. Quantitative mRNA Tg levels were significantly different between patients "free of disease" (82 of 104) and those with metastases (22 of 104) (2.61 +/- 0.26 vs. 27.58 +/- 1.62 pg mRNA Tg/microg RNA) (P < 0.0001). A cutoff point of 5.51 was able to discriminate between the two groups. In addition, the measurement of mRNA Tg was not affected by the presence of TgAb.


CONCLUSIONS
This new mRNA Tg quantification is a reliable method that allowed us to differentiate patients free of disease from those with metastases, and it could represent an appropriate molecular marker for the follow-up of patients with DTC, especially those with positive TgAb.
Boldarine
Valter T
VT
Laboratory of Molecular Endocrinology, Division of Endocrinology, Department of Medicine, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04039-032 Sao Paulo, SP, Brazil.
Maciel
Rui M B
RM
Guimarães
Gustavo S
GS
Nakabashi
Claudia C D
CC
Camacho
Cleber P
CP
Andreoni
Danielle M
DM
Mamone
Maria da Conceição O C
Mda C
Ikejiri
Elza S
ES
Kasamatsu
Teresa S
TS
Crispim
Felipe
F
Hojaij
Flavio C
FC
Hidal
Jairo T
JT
Biscolla
Rosa P M
RP
D000293:Adolescent; D000328:Adult; D000368:Aged; D017931:DNA Primers; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D005260:Female; D006801:Humans; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging; D009362:Neoplasm Metastasis / Q000175:diagnosis; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics; D012372:ROC Curve; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D013954:Thyroglobulin / Q000096:biosynthesis* / Q000235:genetics*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D014463:Ultrasonography; D055815:Young Adult
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D013954:Thyroglobulin