Thyrotoxic periodic paralysis: a presentation of hyperthyroidism increasing in frequency around the world

Abstract

Thyrotoxic periodic paralysis (TPP) is a complication of hyperthyroidism commonly seen in Asian populations. It presents as sudden-onset muscle paralysis and hypokalaemia. Diagnosis is often delayed due to the rarity of the disease, the subtlety of the hyperthyroidism and the fleeting nature of the clinical presentation. With global expansion, physicians outside Asia should be aware of this disease for early recognition and treatment as severe cardiac arrhythmias, which may prove fatal, can occur. Several breakthroughs have been made in identifying the pathophysiological mechanism resulting in the severe hypokalaemia, including mutations in the Kir2.6 channel, an inwardly rectifying potassium channel, which results in a massive intracellular potassium shift. Treating the underlying hyperthyroidism is the definitive treatment; however, beta blockers and potassium supplementation are vital in acute management of this condition. This is a report of a case seen in Cape Town, South Africa with a review of the literature regarding the clinical features, pathophysiology and treatment.