Endocrine Abstracts

Introduction

Thyrotoxicosis debuted early after thyroid lobectomy is described in approximately 54% of cases. It has also been described in a few case reports after non thyroid neck surgeries or in invasive laryngeal cancer after total laryngectomy and debulking hemithyroidectomy.

Case presentation

Patient aged 53 years old, known with laryngeal carcinoma of 37/28/40 mm located at piriform sinus, linked by the left vocal chords, with posterior invasion of cricoid cartilage, and with lysis of the left lamina of the thyroid cartilage. He is referred for surgical cure. One months before surgery the patient had normal TSH and FT4. The day after laryngectomy and debulking left thyroid lobectomy, the patient developed tachycardia (113 bpm), without other symptoms for hyperthyroidism, associated with normal TSH: 0.95 uUI/ml and increased FT4. Day 3 after surgery, TSH was undetectable with a highly increased FT4: 87 pmol/l (4 times x ULN). He received Metoprolol 100 mg/zi and no antithyroid medication. Six days post-surgery, the FT4 levels decreased to almost half 48 pmol/l (2× ULN). At day 12 after surgery, under 100 mg Metoprolol/day, the patient still had tachycardia, with no other signs of hyperthyroidism, the right thyroid lobe was not palpable, while biologically he had only a subclinical thyrotoxicosis TSH: 0.016 uUI/ml, FT4: 18.5 pmol/l (n: 9–19), TPOAb: 14.4 UI/ml (n < 5.6).

Discussion

Thyrotoxicosis debuted early after thyroid lobectomy alone or in the context of other neck surgery (eg for invasive laryngeal cancer) needs correct diagnosis and differentiation from Graves’ disease. It is transient, probably due to cell destruction produced by intrasurgical manipulation of the thyroid gland, therefore requires only symptomatic, but not antithyroid drug treatment. A clue for the diagnosis is the rapid decrease of FT4 and the lack of TRAb antibodies.

Conclusion

Clinicians should be aware of the potential for a transient episode of thyrotoxicosis early after thyroid lobectomy + /- associated with other non-thyroid neck surgeries.