Name:
A 29-Year-Old with Graves’ Disease and Chest Pain
Description:
A 29-Year-Old with Graves’ Disease and Chest Pain
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T00H05M18S
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Upload Date:
2022-02-28T00:00:00.0000000
Transcript:
Language: EN.
Segment:0 .
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CATHY: Hi. Welcome to Harrison's Podclass, where we discuss important concepts in internal medicine. I'm Cathy Handy.
CHARLIE: And I'm Charlie Wiener,
CHARLIE: and we're coming to you from the Johns Hopkins School of Medicine.
CATHY: Welcome to Episode 23: A 29-Year-Old with Graves' Disease and Chest Pain
CHARLIE: Okay, so the question starts, a 29-year old woman is evaluated for anxiety, palpitations, and diarrhea, and she's found to have Graves' disease.
CATHY: Let me take a minute and just comment on Graves' disease because it is the most common cause of hyperthyroidism, or thyrotoxicosis. So, Graves' is an autoimmune phenomenon that's initiated by the production of antibodies against the thyroid-stimulating hormone, or TSH receptor. These antibodies cause excessive thyroid stimulation and the secretion of active thyroxine. Going back to the case, what you mentioned here is a common presentation for Graves' disease.
CATHY: We know it's more common in women compared to men, and the symptoms mentioned here-- anxiety, palpitations, and diarrhea-- are very common symptoms. And you may also see exophthalmos, which is the characteristic ocular finding.
CHARLIE: How is hyperthyroidism diagnosed?
CATHY: The best initial test to diagnose it would be the measurement of serum TSH level. It's typically low or undetectable, so I would expect that in this case. And then total T4 and free T4 levels would be elevated. Another way you can diagnose Graves', in addition to those serologic studies, would be by finding diffuse uptake on thyroid scanning, or the characteristic autoantibodies.
CHARLIE: Back to the question: Before she begins therapy for her thyroid condition, the patient has an episode of acute chest pain and presents to the emergency department. The treating physicians are concerned about a possible pulmonary embolism and order a CT angiogram. The radiologist, however, called to notify the treating physician that this test could be potentially dangerous. Which of the following best explains the radiologist's recommendation?
A: iodinated contrast exposure in patients with Graves' disease may exacerbate the hyperthyroidism. Option B: PE is exceedingly rare in Graves' disease. Option C: radiation exposure in patients with hyperthyroidism is associated with an increased risk of subsequent malignancy; Option D: tachycardia with Graves' disease limits the image quality of CT angiography and will not allow accurate assessment of the presence or absence of a PE. Or Option E: the radiologist is mistaken, CT angiography is safe in patients with Graves' disease.
CATHY: Well, because the patients with Graves' disease have chronic hyperstimulation of their thyroid because they're producing T4, iodine, which is necessary for the thyroid production of T4, results in a relative iodine deficiency. So, in those cases, the production of T4 is limited by the availability of iodine. When you expose patients to iodinated contrast, this can reverse the iodine deficiency and, therefore, you'll get increased secretion of T4 and worsening thyrotoxicosis.
CHARLIE: How may that be life-threatening?
CATHY: The most severe form is thyroid storm, and patients can die from this with severe cardiac or neurologic complications. There are some estimates that the mortality is high as 30%.
CHARLIE: It sounds like Option A is the correct answer-- the iodinated contrast could precipitate thyroid storm. But why are the other answers not correct?
CATHY: Well, the rest of the choices just really aren't great answers. So, PE can certainly happen in patients with Graves' disease, so I wouldn't pick that one. Radiation exposure with single CT study is not associated with an increased risk of secondary malignancies. And tachycardia doesn't preclude the assessment of PE. Remember that tachycardia is a common finding in patients with PE, so that's seen often. And I would agree with the radiologist in this case.
CHARLIE: The question talks about beginning treatment for Graves' disease-- any comment on that?
CATHY: Initially, while toxic, most patients are started on beta blockers to help control the acute symptoms. So, the options for a definitive treatment are antithyroid drugs like methimazole, surgery, or radioactive iodine. And the decision on which to use usually depends on the degree of symptoms and how quickly you need to reduce them. Comorbidities that patients have would also play into the decision of which modality to use. Going back to the question-- another reason to avoid contrast in this patient is that, besides the possibility of acutely worsening symptoms, the reversal of mild iodine deficiency may make iodine-125 therapy for Graves' disease less successful because thyroid iodine uptake is lessened in the iodine-replete state.
CATHY: And iodine-125 works best when the thyroid is so-called "iodine hungry."
CHARLIE: So, giving the iodine in the contrast could actually replete some of the iodine deficiency and make subsequent therapy less effective, right?
CATHY: That's correct.
CHARLIE: Okay, so the teaching point in this case are two: one is that iodinated contrast in patients with Graves' disease should be avoided because of precipitating worsening thyrotoxicosis or even precipitating thyroid storm. And, secondly, giving the iodine can make subsequent therapy with radioactive iodine less effective.
CATHY: For more information, you can check out Harrison's chapter on Disorders of the Thyroid, and the most recent clinical guidelines from the American Thyroid Association and the American Association of Clinical Endocrinologists came out in 2011 on Graves' disease. ♪ (music) ♪