An 80-year-old man is hospitalized because of an acute exacerbation of chronic obstructive pulmonary disease. He is started on high-dose systemic steroids, bronchodilator nebulization, and antibiotics. He initially receives non-invasive positive pressure ventilation for 12 hours. On the third day of hospitalization, his breathing improves but he complains of "fluttering in his chest." He denies chest pain or dizziness. He had similar symptoms in the past that were transient and occurred mostly at night. His other medical problems include type 2 diabetes mellitus, hypertension, hypercholesterolemia, chronic kidney disease, and osteoarthritis.
On examination, he appears comfortable. His temperature is 36.7 C (98 F), blood pressure is 110/60 mm Hg, pulse is 124/min, and respirations are 20/min. The patient's pulse oximetry is 96% on 2 liters of oxygen. His jugular venous pressure is normal. Lung auscultation reveals mild bilateral wheezing and prolonged expiration. He has no hepatomegaly, peripheral edema, or thyromegaly.
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/_Laboratory results are as follows:

ECG reveals atrial fibrillation with rapid ventricular response.
Which of the following would be the most helpful in diagnosing this patient's thyroid disorder?

Question

An 80-year-old man is hospitalized because of an acute exacerbation of chronic obstructive pulmonary disease.  He is started on high-dose systemic steroids, bronchodilator nebulization, and antibiotics.  He initially receives non-invasive positive pressure ventilation for 12 hours.  On the third day of hospitalization, his breathing improves but he complains of "fluttering in his chest."  He denies chest pain or dizziness.  He had similar symptoms in the past that were transient and occurred mostly at night.  His other medical problems include type 2 diabetes mellitus, hypertension, hypercholesterolemia, chronic kidney disease, and osteoarthritis.
On examination, he appears comfortable.  His temperature is 36.7 C (98 F), blood pressure is 110/60 mm Hg, pulse is 124/min, and respirations are 20/min.  The patient's pulse oximetry is 96% on 2 liters of oxygen.  His jugular venous pressure is normal.  Lung auscultation reveals mild bilateral wheezing and prolonged expiration.  He has no hepatomegaly, peripheral edema, or thyromegaly.
/_
/_Laboratory results are as follows:

ECG reveals atrial fibrillation with rapid ventricular response.
Which of the following would be the most helpful in diagnosing this patient's thyroid disorder?

Quizplus · Accepted Answer

11ec193a_96c4_2fc1_853d_6d8146ae1153_MD0002_00 This patient's presentation is consistent with euthyroid sick syndrome (ESS). Euthyroid sick syndrome usually occurs due to decreased conversion of T4 to T3, decreased T4 production and clearance, altered T4 protein binding, and TSH suppression. In addition to illness-associated TSH suppression, medications (e.g., glucocorticoids, dopamine, octreotide) given to hospitalized patients may also suppress TSH levels. Laboratory studies usually reveal a low serum T3 level (low T3 syndrome) due to decreased peripheral conversion of T4 to T3 by the enzyme 5'-monodeiodinase (reduced activity during illness). T3 levels are usually the first to decrease; if the illness continues, then serum TSH and T4 also become suppressed. This patient's acute atrial fibrillation is most likely due to an underlying illness. However, it is important to rule out thyrotoxicosis. Serum T3 levels will likely be high in thyrotoxicosis, but low to low-normal in glucocorticoid-induced TSH suppression and low in ESS. Although TSH may be suppressed in ESS, the levels are typically detectable and may become transiently elevated during the recovery period. In contrast, the majority of patients with undetectable TSH (< 0.01 mU/L) have hyperthyroidism. Thyroxine therapy has not been shown to be beneficial for ESS patients, and thyroid function usually improves after recovery from illness. (Choice A) Radioactive iodine uptake and scan would be useful in patients with elevated serum T3. (Choice B) Thyroid function tests can be repeated a few days after confirming a diagnosis of ESS, but T3 must first be ordered to confirm the diagnosis. (Choice C) Serum rT3 is elevated in ESS because the enzyme 5'-monodeiodinase is also responsible for its catabolism. However, rT3 levels may also be elevated in renal failure and would not be useful in this patient. (Choice D) Thyroid ultrasound is an excellent test for assessing structural thyroid problems, but is not generally useful for diagnosing thyroid dysfunction. Educational objective: Hospitalized patients commonly have low T3 due to illness suppressing the conversion of T4 to T3. In the setting of low TSH, measuring T3 levels can differentiate between hyperthyroidism (high T3) and euthyroid sick syndrome (low T3). Treating patients with euthyroid sick syndrome is not beneficial, and thyroid function usually normalizes a few weeks after recovery from illness. __________ References: Thyroid axis function and dysfunction in critical illness. (http://www.ncbi.nlm.nih.gov/pubmed/21925075) Thyroid hormone indices during illness in six hypothyroid subjects rendered euthyroid with levothyroxine therapy. (http://www.ncbi.nlm.nih.gov/pubmed/15239022)

An 80-Year-Old Man Is Hospitalized Because of an Acute Exacerbation