Fatal thyroid crisis years after two thyroidectomies for graves' disease: is thyroid tissue autotransplantation for postthyroidectomy hypothyroidism worthwhile?

Abstract

We read with great interest about the trial of autotransplantation of cryopreserved thyroid tissue for postoperative hypothyroidism in patients with Graves’ disease by Dr Shimizu and colleagues that was published in the January 2002 issue of this journal. The idea of eliminating the need for lifelong L-thyroxine replacement because of thyroprivic hypothyroidism undoubtedly appeals to the patients. But what concerns us is that three out of the four subjects who consented to the procedure did so with a view to relieve them from frequent followup visits. Although the authors maintained that the appropriate amount of thyroid tissue could be easily removed from the forearm under local anesthesia should recurrent hyperthyroidism occur, it should be appreciated that an inherent risk exists in selecting such subjects for this procedure. Because these patients opted for autotransplantation with a view to decrease the need for frequent longterm followups, they are also exposed to the risk of severe or even potentially fatal thyroid crisis should there be undue delay in the detection and treatment of a relapse. As to the point that no cases of recurrent hyperthyroidism have been seen as a result of autotransplantation of thyroid tissue, such a conclusion is premature and would require careful evaluation of a large number of subjects over an extended period of followup to be certain. The incidence of relapse of thyrotoxicosis in those who had subtotal thyroidectomy can approach 18%, and the mean duration to relapse postthyroidectomy ranges from less than a year to 30 years or more. For those who relapsed after subtotal thyroidectomy, we would favor iodine therapy with the aim of achieving total thyroid ablation. This is because Graves’ disease, unlike other forms of hyperthyroidism, carries a persistent risk of relapse whenever remnant thyroid tissue is left behind. To underscore our point, we report a patient presenting with severe thyroid storm despite two previous thyroidectomies for persistent thyrotoxic Graves’ disease. The patient was a 53-year-old Chinese woman who first underwent subtotal thyroidectomy in 1980 after 2 years of failed thionamide therapy. Because of a relapse 3 years later, a near-total thyroidectomy was done in 1983. She remained biochemically and clinically euthyroid for nearly 18 years after the two operations. On April 19, 2001, she developed pneumonia and was admitted to the hospital. Clinically, she was pyrexial, diaphoretic, and stuporous. A prominent lid-lag with lid retraction was present, accompanied by fine tremors of her upper extremities. A thyroidectomy scar was visible, with no palpable thyroid tissue. She was in rapid atrial fibrillation and congestive cardiac failure. She was evidently suffering from thyroid storm, and propylthiouracil and sodium iodide were initiated after blood samples were collected. Propranolol was administered cautiously with digoxin and diuretics to control her heart failure. Initial blood investigations revealed free T4 61pmol/L (normal range 10–20), free T3 15.7pmol/L (normal range 5.8– 8.7), thyroid stimulating hormone (TSH) 0.01mIU/L (normal range 0.40–3.98), and TSH receptor autoantibody 17.8U/L (normal range 3.4). Over the next 5 days, she remained tachypneic and hypotensive. She died from multisystem failure 5 days later. This case serves as a grave reminder that surgical resection of the thyroid in Graves’ disease, no matter how radical it is, does not always render the patient permanently hypothyroid or confer absolute immunity to future recurrence of the illness. So we advocate iodine therapy to achieve total thyroid remnant ablation in patients with persistently active thyroid autoimmunity presenting with relapse postthyroidectomy. Relapse of thyrotoxicosis after near-total thyroidectomy is estimated at about 3%. Thyroid crisis complicating the longterm course of near-total thyroidectomy is believed to be an exceedingly rare occurrence. Our patient led us to consider what critical amount of thyroid tissue remnant could confer a significant risk of relapse of thyrotoxicosis. Although past researchers had established that the probability of relapses becomes in-