Hypokalemic thyrotoxic periodic paralysis: clinical characteristics and predictors of recurrent paralytic attacks.

BACKGROUND AND PURPOSE: To study the clinical characteristics of hypokalemic thyrotoxic periodic paralysis (hoTPP) and identify the predictors of recurrent paralytic attacks before achieving the euthyroid status.

METHODS

We retrospectively analyzed 45 hoTPP patients who were admitted during the 7-year study period.

RESULTS

A tendency towards male predominance was observed among the 45 patients (91.1%, 41/45). The mean onset age was 32.9 +/- 10.0 years (range: 16-54 years). No significant differences were observed in the onset age between male and female patients. Precipitating factors included rest/sleep at night, hot weather, upper respiratory tract infections (URIs), and excessive physical activities. Atypical weakness was observed in nine (20%, 9/45) patients. One patient initially diagnosed with sporadic periodic paralysis eventually developed hoTPP.

DISCUSSION: In provocative tests, hypokalemia was not a consistent finding during paralytic attacks. Before achieving the euthyroid status, the rate of recurrent attacks was as high as 62.2%, and peaked in the first 3 months after hoTPP was diagnosed. Patients with URIs exhibited a higher incidence of recurrent paralytic attacks than those without (odds ratio = 13.00; 95% confidence interval = 1.08-156.08; P = 0.04).