A 62 y/o white female wit hyperthyroidism , diagnosed in the last 2 months c/w graves disease with severe exophthalmos , positive TSI ( no able to get the thyroid uptake and scan since she had a CT scan with contrast in the last 8 weeks ) – she was also found to have a mediastinal mass. She is taking now tapazole 30 mg poqd – and after 6 weeks her Free T4 is normal , her TSH is still low . She is going for surgery , biopsy of the mediastinal mass and possible thyroidectomy at the same time , but may need cardiac cath since she has abnormal stress test ;according to the cardiologist .Which ones should be the precautions at this time , since she is clinically euthryoid ,taking tapazole ;in case she needs the cardiac cath –due to the load of IODINE .. What other precautions should I take?
If she does have a cath, maintaining Tapazole 10 mg q8h should provide sufficient block to prevent iodide uptake and an induced exaccerbation.But actually, a big iodine load probably would be therapeutic for her hyperthyroidism. You will want to maintain the Tapazole for 2-4 weeks after any iodide load to allow the iodine and dye to be excreted.
The mediastinal mass is very interesting, and I expect you have considered the possibility of an enlarged thymus, which often occurs in Graves' disease, and might occur even in a 62 year old.
With severe exophthalmos, I would encourage consideration of thyroidectopmy as the prime treatment of her Graves, followed by RAI ablation of any residual tissue when possible, and with care to avoid hypothyroidism during her treatment as it may exacerbate the exophthalmos. You might consider thyroidectomy and biopsy of the mass.
L De Groot, MD