A patient with known primary medullary thyroid carcinoma was found at autopsy to have a recurrence in the thyroid, and metastases in liver, lungs, and lymph nodes. Thyrocalcitonin (TCT) levels in these tissues as well as in lung and liver tissues surrounding the metastases were determined by bioassay in young rats against Medical Research Standard (MRC) B porcine TCT. All the involved tissues were found to contain high levels of TCT: the primary carcinoma containing the highest at 221 U/gm (MRC units per gram). The metastases to the lymph nodes, lungs, and liver demonstrated 60 U/gm, 38 U/gm, and 26 U/gm TCT, respectively. Although normal human lung and liver contain no appreciable quantity of TCT, the lung and liver tissues surrounding the metastases in this patient demonstrated 18 U/gm and less than 8 U/gm TCT, respectively.
Aliapoulios MA, Kacoyanis GP. Primary and Metastatic Medullary Thyroid Carcinoma: Determination of Thyrocalcitonin Content by Bioassay. Arch Surg. 1973;106(1):105–108. doi:10.1001/archsurg.1973.01350130101024
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