Comparative evaluation of recombinant human thyrotropin-stimulated thyroglobulin levels, 131I whole-body scintigraphy, and neck ultrasonography in the follow-up of patients with papillary thyroid microcarcinoma who have not undergone radioiodine therapy

Context: Although the prognosis of papillary thyroid microcarcinoma (PTMC) is usually excellent, the optimal follow-up strategy has never been investigated. Objective: The objective of the study was to investigate the role of neck ultrasonography (US), whole-body scintigraphy (WBS), and serum thyroglobulin levels (Tg) after recombinant human (rh) TSH in the follow-up of very low-risk PTMC patients. Design: The study was a 5-yr observational study based on a 6- to 12-month follow-up after near total thyroidectomy. Setting: The study population consisted of ambulatory patients. Patients: Eighty consecutive patients diagnosed with PTMC, who had not undergone postoperative radioiodine treatment because of unifocal tumor without lymph node metastases and who did not have anti-Tg antibodies, were included. Main Outcome Measures: WBS and Tg after both rhTSH and neck US were measured. Results: rhTSH-Tg was 1 ng/ml or less in 45 (Tg-) and more than 1 in 35 (Tg+) patients. WBS showed no pathological uptake in any patient. US identified node metastases in two Tg (+) and one Tg (-) patients. rhTSH-Tg levels positively correlated with thyroid bed iodine uptake (r=0.40, P<0.0001). To date (32 +/- 13 months after surgery), all node-negative patients have undetectable Tg levels on LT4 treatment and negative US. Conclusions: For the initial follow-up of PTMC patients without risk factors and anti-Tg antibodies and who did not undergo radioiodine treatment: 1) WBS is useless; 2) US is highly sensitive in detecting node metastases; and 3) detectable rhTSH-Tg levels mainly depend on small normal tissue remnants. In this subgroup of PTMC patients, neck US might be regarded as a primary tool for the initial follow-up.