A 32 year old female presented with anxiety, palpitations, and diarrhea. Lab studies show elevated T4, TSH levels are low & increased long acting thyroid stimulating antibody titres. A diagnosis of Graves disease is made. But then the patient came to emergency with sudden onset of acute chest pain. CT angiography which is useful in making the diagnosis of pulmonary embolism, can be potentially dangerous in this patient because:
Patients with Graves disease produce higher levels of T4, as a result they are mildly iodine deficient, thus T4 production is somewhat limited. Iodinated contrast reverses iodine deficiency and may precipitate worsening of hypehyroidism. It may make iodine-125 therapy less successful because thyroid iodine uptake is decreased in the iodine-repleted state.
Iodinated contrast exposure in patients with Graves disease may exacerbate hypehyroidism.
Pulmonary embolism is exceedingly rare in Graves disease.
Radiation exposure in patients with hypehyroidism is associated with increased risk of subsequent malignancy.
Tachycardia with Graves disease limits the image quality of CT angiography and will not allow accurate assessment of pulmonary embolism.
Diseases of Thyroid