Q: What is consumptive hypothyroidism?
Answer: Consumptive hypothyroidism is a form of hypothyroidism characterized by excessive degradation of thyroid hormone. This is due to ectopic production of type 3 deiodinase, which metabolizes T4 to reverse T3 and T3 to T2.
This ectopic production signifies underlying vascular and fibrotic tumors and is found to be highly associated wiith gastrointestinal stromal tumors.
In such patients Reverse T3 (rT3) is usually high which is an inactive metabolite of thyroxine.
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2. Maynard MA, Marino-Enriquez A, Fletcher JA, et al. Thyroid hormone inactivation in gastrointestinal stromal tumors. N Engl J Med 2014; 370:1327.
3. Schmidt RL, LoPresti JS, McDermott MT, et al. Does Reverse Triiodothyronine Testing Have Clinical Utility? An Analysis of Practice Variation Based on Order Data from a National Reference Laboratory. Thyroid 2018; 28:842.