Thyrotoxic, hypokalaemic periodic paralysis: Polynesians, an ethnic group at risk.

BACKGROUND: Thyrotoxic, hypokalaemic periodic paralysis (TPP) is a reversible cause of severe muscle weakness that occurs in a small minority of thyrotoxic patients. Most cases to date have been reported in Asian men.

AIMS: To evaluate the ethnic distribution of patients with TPP.

METHODS: Retrospective analysis of all patients presenting with thyrotoxicosis and hypokalaemia with paralysis to two New Zealand hospitals.

RESULTS: Seventy-one per cent of the 21 patients with TPP were of Polynesian ethnicity (Maori and Pacific Islander), 24% Asian and 5% European. Based on population demographics, these figures suggest a 37-fold overrepresentation for Polynesians and 159-fold for Asians compared with New Zealand Europeans.

CONCLUSION: Polynesian, in addition to Asian people, are two ethnic groups at particular risk of TPP, and this condition must be considered in the differential diagnosis for patients presenting to the emergency department with severe hypokalaemia and weakness.