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).