Serum thyreoglobulin (Tg) and whole body scintigraphy (I-131 WBS) have been used to detect recurrent and metastatic thyroid cancers postoperatively. However, discordant results of Tg measurement and 131I WBS have been reported. Negative 131IWBS and a positive Tg test are usually found, but less common occurrence of positive 131IWBS and a negative Tg test has also been demonstrated in a small but significant number of cases. Therefore, the aim of the study was to retrospectively analyse patients with positive 131I WBS after total thyreoidectomy and again 1 year after the radioactive iodine.
There were 52 patients included in the study. Four weeks after surgery, during which thyroid hormone treatment was not introduced, each patient received an ablative dose of 131I. The evaluation of the WBS was qualitative and considered positive if thyroid remnant, lymphatic node or metastasis were detected. WBS and serum Tg was measured 12 months after 131I ablation with thyroid hormone suppression. We considered positive any Tg level above the sensitivity values and negative if lower than this level. Tg levels were related to the existence of a positive scan or a negative one. In our 52 WBS positive patients concordant positive Tg levels were observed in 42 patients while in 10 patients we found a negative Tg levels after the surgery. After 1-year follow-up, out of initially 42 concordant patients 8 patients showed remaining concordant positive Tg and WBS values. Discordant results were observed in 13 patients (4 patients were Tgand WBS+ while 9 patients were Tg+ and WBS-). In the majority of patients (50%) remained with concordant results
but changed from Tg+ and WBS+ to Tg- and WBS-. Diagnostic WBS is an additional valuable tool, besides Tg levels, in the follow up of patients after total thyreoidectomy
