[Thyrotoxic periodic paralysis: a case series of four patients and literature review]

Abstract

Purpose: Periodic thyrotoxic hypokalemic paralysis (TPP) is a neuromuscular complication of hyperthyroidism. It is more common in young Asian males than in Caucasian and African patients. We report four new cases and review the literature.

Case reports: Four consecutive patients were diagnosed with TPP. They were all men with a median age of 34.5 years at presentation. Two patients originated from the Philippines, one was African and one was Caucasian ethnic background. They all presented with a paresis or flaccid paralysis, without respiratory failure. Previous similar episodes in their past medical history, the presence of profound hypokalemia (mean serum potassium level of 2 mmol/L) and the presence of clinical and biological signs of hyperthyroidism led to the diagnosis of TPP. All four patients were diagnosed with Graves' disease. Outcome was favourable in all four patients with the symptomatic treatment of TPP and treatment of Graves' disease.

Conclusion: TPP is a severe condition, due to a dysfunction of the Na(+)-K(+) ATPase pump. Initial management relies on β-blocker treatment and careful potassium supplementation. Then, medical or surgical etiological treatment of the thyrotoxicosis is essential to prevent a recurrence. The disease is probably underdiagnosed: it must be suspected when a profound hypokaliema resolves very quickly (<12hours); hyperthyroidism should always be included in the differential diagnosis of a paresis associated with hypokalemia.

Keywords: Hyperthyroidism; Hyperthyroïdie; Hypokalemia; Hypokaliémie; Paralysie périodique thyréotoxique; Periodic thyrotoxic hypokalemic paralysis.