Abstract
BackgroundNon-thyroidal illness (NTI) refers to changes in thyroid hormone levels in critically ill patients in the absence of primary hypothalamic-pituitary-thyroid dysfunction, and these abnormalities usually resolve after clinical recovery. However, NTI can be accompanied by primary thyroid dysfunction. We report herein a case of a woman with NTI accompanied by primary hyperthyroidism.Case presentationA 52-year-old female was admitted to the intensive care unit with heart failure and atrial fibrillation. She had a longstanding thyroid nodule, and a thyroid function test revealed low levels of triiodothyronine and free thyroxine as well as undetectable thyroid stimulating hormone (TSH). She was diagnosed with NTI, and her TSH level began to recover but not completely at discharge. The thyroid function test was repeated after 42 months to reveal primary hyperthyroidism, and a thyroid scan confirmed a toxic nodule.ConclusionThis case suggests that although NTI was diagnosed, primary hyperthyroidism should be considered as another possible diagnosis if TSH is undetectable. Thyroid function tests should be repeated after clinical recovery from acute illness.
Highlights
Non-thyroidal illness (NTI) refers to changes in thyroid hormone levels in critically ill patients in the absence of primary hypothalamic-pituitary-thyroid dysfunction, and these abnormalities usually resolve after clinical recovery
She was diagnosed with NTI accompanying heart failure and a decision was made not to replace thyroid hormones but to followup on the thyroid function testing
Primary hyperthyroidism, toxic adenoma, should be considered in patients with NTI who have an undetectable level of thyroid stimulating hormone (TSH) and a huge nodule with an atrophic remaining thyroid gland
Summary
Non-thyroidal illness (NTI) or euthyroid sick syndrome (ESS) is defined as a change in thyroid function during starvation or illness including a central reduction in thyroid stimulating hormone (TSH) secretion, decreased plasma triiodothyronine (T3) levels and decreased thyroxine (T4) and T3 binding in serum [1]. An endocrine consultation was sought to evaluate the possibility of thyroid disease She was diagnosed with NTI accompanying heart failure and a decision was made not to replace thyroid hormones but to followup on the thyroid function testing. The thyroid function tests were not followed up until February 2012 (42 months) when she consulted the endocrinology department again for follow-up of the thyroid nodule Her free T4 and T3 levels had increased to 5.30 ng/dL and 4.80 ng/mL, respectively, and TSH was < 0.005 μIU/mL. A 99m-Technetium-pertechnetate thyroid scan demonstrated heterogeneous uptake in the large nodule of the right thyroid gland with no visibility in the remaining gland, suggesting a functioning toxic nodule (Figure 2) She refused an operation or radioactive iodine therapy; 10 mg methimazole twice per day was prescribed. 0.941 ng/mL, respectively) 2 weeks later, and TSH was 0.009 μIU/mL
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