TITLE:
Consumptive Hypothyroidism: T3 or Not T3, That Is the Question
AUTHORS:
Kevin Hess, Soraya Bascoy, James Lenhard
KEYWORDS:
Hypothyroidism, Consumptive Hypothyroidism, Neuroendocrine Tumors
JOURNAL NAME:
Open Journal of Endocrine and Metabolic Diseases,
Vol.11 No.10,
October
31,
2021
ABSTRACT: Consumptive hypothyroidism is often the clinical condition that results
from neoplasms producing their own selenodionases that convert T4 needed to be
converted to active T3 into an active form of thyroid hormone, rT3. This often
requires treatment with high doses of IV T4, with or without doses of T3 as
well, until the neoplasm is treated. This principle is demonstrated in the
below case of a 65 y/o female with medical history significant for Ia Kappa
multiple myeloma, complete heart block s/p AICD placement, and papillary
thyroid cancer status post thyroidectomy in 2020, who had initially presented with persistent bone pain, progressive
encephalopathy and failure to thrive with more than a 50 lb weight loss
over a few months. Labs on presentation were
not remarkable for progression of her underlying multiple myeloma,
however, she
was found to have a new significantly elevated TSH. She underwent imaging with
a CT chest, abdomen, and pelvis, which showed new hepatic lesions, subcutaneous
nodules, and new pulmonary nodules with associated lymphadenopathy and a
left-sided pleural effusion. CT-guided liver biopsy evinced a metastatic
neuroendocrine carcinoma, further supported by an elevated calcitonin and
chromogranin. She was treated with high dose IV T4 at 1.38 mcg/kg however
continued to worsening thyroid function labs. She was then started on
Liothyronine at 20 mcg and subsequently improved. This patient’s case illustrates the importance of considering consumptive
hypothyroidism when thyroid profile
abnormalities and symptoms of severe hypothyroidism are seen in the
context of malignant neoplasms, and further illustrates the important of considering T3 as part of the treatment regimen when IV T4 is not resulting in improvement.