Thyroglobulin Determination, Neck Ultrasonography and Iodine-131 Whole-Body Scintigraphy in Differentiated Thyroid Carcinoma

The long-term prognosis of patients with differentiated thyroid carcinoma depends on the early diagnosis and treatment of metastases and local recurrences. We evaluated serum thyroglobulin measurements, neck ultrasonography with ultrasound-guided biopsy and 131I whole-body scintigraphy in the follow-up of 359 patients after surgical thyroidectomy and radioiodine ablation of the thyroid remnant. Serum thyroglobulin levels were determined and considered abnormal when the values were > 5 ng/ml. Ultrasonography over the entire neck region and fine-needle aspiration biopsy of the mass or enlarged lymph nodes were carried out using 5- and 7.5-MHz transducers and 23-gauge needles. Whole-body scintigraphy was performed after administration of 185 MBq (5 mCi)131I. Increased levels of thyroglobulin (ranging from 12 to > 600 ng/ml) were measured in 40 of 55 (73%) patients with metastases or local recurrences. Ultrasonography revealed occult neck masses that were not detected by other methods. Neck ultrasonography and ultrasound-guided biopsy were positive for malignancy in 23 patients. Thyroglobulin levels were undetectable in 12 (52%) of these patients and 131I whole-body scintigraphy was negative in 19 (83%) of them. The combined use of three diagnostic modalities (measurement of serum thyroglobulin, neck ultrasonography with ultrasound-guided biopsy for detecting recurrences of carcinoma in the neck region and 131I whole-body scintigraphy) appears to give the best results in the follows-up patients with differentiated thyroid carcinoma.