engleski

Detection of thyroid hormones produced by thyroid remnant or thyroid metastases

Radiolabelled thyroid hormones and their precursors (131-T3/T4 and 131-I-T2), produced by any thyroactive tissue (thyroid remnant or metastases), could be detected chromatografically in serum or urine of patients with operated differentiated thyroid cancer. Since 1993 we have been using chromatography additionally to 131-I-whole body scan, ultrasonography of the neck and thyroglobulin determination. The aim of the study was to evaluate the percentage of patients with thyroactive tissue left after thyroidectomy and radioablation with 131-I. A total of 202 chromatographies (162 in serum and 40 in urine) were performed for 94 differentiated thyroid cancer patients who were followed-up one to nine times in the period from 1993-1998. The main points observed during the chromatography study were these: 1. 131-T3/T4 peak was registered in 53% of patients after total thyroidectomy and radioablation (47% in serum and 10% in urine samples). 2. 131-I-3,3’-T2 peak was detected in 45% of patients (46% in serum and 13% in urine samples). 3. On urine chromatogram, which usually contains only 131-I-iodide, both radiolabelled products were found in patients with measurable serum T3 and T4 concentrations. 4. In serum and urine samples of some patients, that were taken during the follow-up study, 131-I-T3/T4 peak or/and 131-I-3,3’-T2 peak were registered consecutively or randomly. Serum and urine chromatography results suggest that iodine metabolism of differentiated thyroid cancer is very variable-it differs in the number of peaks and in peak radioactivity, not only from patient to patient, but also during the follow-up of the same patient. Variations in iodine metabolism are probably dependent on the amount of residual or metastatic thyroid tissue, thyrocyte’s membrane permeability, the strength of iodine accumulation in thyrocytes, renal function and possibly on other factors.

Detection of thyroid hormones produced by thyroid remnant or thyroid metastases

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