SAT-385 - New Onset Atrial Fibrillation with Rapid Ventricular Response from Thyroiditis Following Parathyroidectomy for Primary Hyperparathyroidism

Background

Thyroiditis following parathyroid surgery is relatively common but typically does not have clinically significant consequences. In one study, 24% of patients developed transiently suppressed thyroid stimulating hormone (TSH), but only 2% of patients developed symptoms of hyperthyroidism [1]. Thyroiditis in these cases is believed to be due to manipulation of thyroid tissue during parathyroid surgery [1]. The following case demonstrates that thyroiditis following parathyroid surgery can result in severe complications including new onset atrial fibrillation with rapid ventricular response.

Case

An 80-year-old woman with a history of osteoporosis who underwent left superior parathyroidectomy for primary hyperparathyroidism one week prior presented to the emergency department with dizziness. She was diagnosed with new onset atrial fibrillation with rapid ventricular response despite having no prior cardiac history. TSH level was 0.02 mIU/L and free thyroxine (FT4) level was 3.9 ng/dL with normal thyroid studies prior to that. Sestamibi scan prior to parathyroid surgery revealed a focus of retained radiotracer inferior to the right thyroid lobe suspicious for right inferior parathyroid adenoma. However, intraoperative biopsies of right inferior and superior parathyroids revealed normal parathyroid tissue and intraoperative biopsy of left superior parathyroid revealed hypercellular parathyroid tissue. Intact parathyroid hormone level improved from 103 pg/mL to 51 pg/mL following resection of left superior parathyroid. Beta blockade was initiated with gradual improvement in heart rate from 120 to 80 beats per minute and conversion to normal sinus rhythm. TSH and FT4 levels both normalized within four weeks of hospitalization, at which time beta blockade was discontinued.

Conclusion

This unusual case demonstrates that a patient with no known history of cardiac disease can develop atrial fibrillation from severe thyroiditis following parathyroid surgery. Both surgeons and endocrinologists must be aware of the risk of thyroiditis so that they can educate their patients regarding signs and symptoms of thyroiditis following parathyroid surgery to prevent serious complications of untreated thyrotoxicosis. This is especially important if there needs to be significant manipulation of thyroid tissue during the surgery. Future research might allow care teams to better predict the risks of developing thyroiditis and complications from thyroiditis following parathyroid surgery in individual patients.

References

[1] Wang R, et al. (2024). Retracting the thyroid matters: Who develops asymptomatic transient thyrotoxicosis after parathyroidectomy. The American Journal of Surgery, 230, 9-13.

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