Prediction of disease status by recombinant human TSH-stimulated serum Tg in the postsurgical follow-up of differentiated thyroid carcinoma.
Stimulation with recombinant human TSH (rhTSH) has been introduced in clinical practice as an effective alternative to thyroid hormone withdrawal for the diagnostic follow-up (Tg measurement and 131-iodine whole-body scan) of patients with differentiated thyroid cancer. The present study was specifically aimed to evaluate the utility of rhTSH-stimulated serum Tg measurements in patients with undetectable serum Tg values, on L-T(4) therapy, as the only test to differentiate patients with persistent disease from patients who are disease-free. We studied 72 consecutive patients with differentiated thyroid cancer, previously treated with near-total thyroidectomy and 131-I thyroid ablation. Admission criteria were: an undetectable (<1 ng/ml) serum Tg, on L-T(4) therapy, and negative anti-Tg antibodies. The study design consisted of a Tg-stimulation test after rhTSH, during L-T(4), followed by diagnostic WBS and serum Tg measurement off L-T(4). After rhTSH, serum Tg remained undetectable in 41 of 72 patients (56.9%). A negative rhTSH Tg test agreed with an undetectable hypo-Tg in 36 of 41 cases (87.8%), all without evidence of metastatic disease at hypo-WBS. In 5 of 41 cases (12.2%), hypo-Tg was detectable (1.1-7.8 ng/ml), in association with negative hypo-WBS or faint uptake in the thyroid bed. Serum Tg converted from undetectable to detectable after rhTSH in 31 of 72 patients (43.1%), with a peak Tg ranging between 1.2 and 23.0 ng/ml. Hypo-Tg was always detectable in these patients (100% concordance), and it was significantly higher than rhTSH-stimulated Tg (P < 0.0002). Hypo-WBS was positive in 23 of 31 patients (74.2%), showing thyroid residues in 12, cervical lymph nodes in 7, and lung metastases in 4 cases. In 8 of 31 cases, hypo-WBS was negative, despite detectable serum Tg. Thus, rhTSH-stimulated Tg was able to detect all cases of documented local or distant metastases. In conclusion, our data indicate that, in patients with undetectable basal levels of serum Tg, rhTSH-stimulated Tg represents an informative test to distinguish disease-free patients (not requiring WBS) from diseased patients (requiring further diagnostic and/or therapeutic procedures).
Pacini
F
F
Department of Endocrinology and Metabolism, University of Pisa, 56124 Pisa, Italy. fpacini@endoc.med.unipi.it
Molinaro
E
E
Lippi
F
F
Castagna
M G
MG
Agate
L
L
Ceccarelli
C
C
Taddei
D
D
Elisei
R
R
Capezzone
M
M
Pinchera
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D011379:Prognosis; D011994:Recombinant Proteins / Q000494:pharmacology; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D013965:Thyroidectomy; D013972:Thyrotropin / Q000097:blood / Q000494:pharmacology*; D013974:Thyroxine / Q000627:therapeutic use
D011994:Recombinant Proteins; D013972:Thyrotropin; D013954:Thyroglobulin; D013974:Thyroxine