Endocrine Abstracts

Thyrotoxic period paralysis is a rare endocrine emergency associated with hyperthyroidism that needs urgent treatment. We present a case of a 19-year-old Chinese student who was admitted with progressive weakness in his lower limbs developing overnight. He was resident at the students’ hostel and went to sleep after ignoring mild leg weakness overnight but could not even get up from his bed in the morning. Luckily his friend called the ambulance and brought him in hospital.

At the time of admission he was found to be completely flaccid with a power of 1 out of 5 (on MRC scale) in all four limbs. The pattern of rapidly ascending flaccid paralysis with preserved cognition raised the suspicion of Guillain-Barre syndrome. But his potassium was 1.7 mmol/l and ECG was showing junctional tachycardia with long QTc (630 ms) which led to the differentials of hypokalaemic periodic paralysis. There had been a similar self-resolving milder episode of leg weakness three months ago. The thyroid functions showed overt thyrotoxicosis (TSH <0.01 mU/l, FT₄ >100 pmol/l, FT₃=35.8 pmol/l) despite the patient being clinically eu-thyroid (with the exception of tachycardia). The patient was kept on cardiac monitoring and treated by correction of hypokalaemia along with commencement of propranolol and carbimazole. There was complete recovery of the neurological deficit within 4 h.

This case reminds the importance of a rare presentation of thyrotoxicosis in southeast Asian people which can be life threatening as a result of the arrhythmogenic potential of combination of profound hypokalaemia with severe thyrotoxicosis. These people are candidates for definitive treatment of their thyrotoxicosis in form either radio-iodine or thyroidectomy.