Severe thyrotoxicosis after parathyroid surgery for hyperparathyroidism

Thyroiditis After Parathyroidectomy

Various clinical manifestations of thyroiditis after parathyroidectomy have been reported in the literature, ranging from mild symptoms to tachyarrhythmias and myocardial infarction. We report 2 cases of post-parathyroidectomy thyroiditis. Both patients had primary hyperparathyroidism and underwent parathyroidectomy for a solitary parathyroid adenoma. They subsequently developed symptoms of hyperthyroidism, including palpitations and heat intolerance. Laboratory investigations demonstrated a suppressed TSH level with elevated free T4 levels and low uptake on thyroid radioiodine scan, confirming the diagnosis of thyroiditis. The patients were managed conservatively, and their symptoms gradually resolved with normalization of thyroid hormone levels. A review of 27 cases reported to date reveals that this condition is mostly attributed to manipulation of the thyroid during parathyroid surgery. It occurs more frequently in patients who undergo 4-gland parathyroidectomy for secondary or tertiary hyperthyroidism and is self-limited within a few weeks. The case reports highlight the importance of recognizing thyroiditis as a potentially underrecognized complication of parathyroid surgery. Further research is warranted to better understand the underlying pathophysiology and to establish potential risk factors for its development post-parathyroidectomy.

Transient hyperthyroidism after surgery for secondary hyperparathyroidism: a common problem

Background

Postoperative hyperthyroidism occurs in approximately one third of patients following parathyroidectomy due to primary hyperparathyroidism (PHP), but has only rarely been described in secondary hyperparathyroidism (SHP). The frequency, course, and laboratory markers of postoperative hyperthyroidism in SHP remain unknown. Our purpose was to evaluate the frequency and the clinical course of postoperative hypcrthyroidism following surgery of SHP and to determine the diagnostic value of thyroglobulin in this setting.

Material and Methods

A total of 40 patients undergoing parathyroidectomy because of SHP were included in this study. Thyroid stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fl4), and thyroglobulin (Tg) were determined one day before and on day 1, 3, 5, 10, and 40 after surgery. At each of these visits patients were clinically evaluated for signs or symptoms of hyperthyroidism.

Results

Biochemical evidence of hyperthyroidism was evident in 77% of patients postoperatively despite of preoperatively normal serum levels. TSH dropped from 1.18 ± 0.06mU/L to 0.15 ± 0.07mU/L (p = 0.0015). Free triiodothyronine (fT3) and fT4 levels increased from 2.86 ± 0.02ng/L and 10.32 ± 0.13ng/L, respectively, to their maximum of 4.83 ± 0.17ng/L and 19.35 ± 0.58ng/L, respectively. Thyroglobulin levels rose from 3.8 ± 0.8ng/mL to 111.8 ± 45.3ng/mL (p < 0.001). At day 40 all thyroid related laboratory values were within normal range. Correlation analysis of postoperative values revealed significant correlations for lowest TSH (r = -0.32; p = 0.038), and highest fT3 (r = 0.55; p < 0.001) and fT4 levels (r = 0.67; p < 0.001) with Tg.

Conclusion

Transient hyperthyroidism is frequent after parathyroidectomy for SHP with Tg being a suitable marker. Awareness of this self-limiting disorder is important to avoid inappropriate and potentially harmful treatment.

Post-parathyroidectomy thyrotoxicosis and atrial flutter: a case for caution

Despite transient hyperthyroidism reportedly occurring in ∼30% of post-parathyroidectomy (PTX) patients with primary hyperparathyroidism, it has rarely been described in the internal medicine literature. It occurs within days of surgery, is usually clinically mild or silent, and typically spontaneously resolves within weeks. Patients can, however, unusually present with symptoms and signs of thyrotoxicosis, including arrhythmias. We report a case of a hemodialysis patient who developed self-limited hyperthyroidism after intra-operative thyroid manipulation and excision during PTX surgery for secondary hyperparathyroidism that failed medical management. The patient was symptomatic with agitation, restlessness and new-onset atrial flutter, which required electrical cardioversion and temporary beta blockade. It is important that clinicians be aware of this potential surgical complication, so as to not attribute manifestations to post-PTX divalent cation disorders (i.e. hungry bone syndrome), thereby allowing prompt diagnosis and treatment. Post-operative monitoring of thyroid function is warranted for at least some subsets of patients: individuals who undergo thyroid exploration and palpation as part of their surgery to localize the parathyroid glands, as well as those with underlying cardiac disease or who are otherwise at high risk from even mild states of hyperthyroidism.