Hypokalemic periodic paralysis as a manifestation of thyrotoxicosis.

OBJECTIVE: To study the clinical characteristics of patients who suffer from hypokalemic periodic paralysis, as the presenting symptoms of thyrotoxicosis. MATERIAL AND METHOD: A retrospective review of 29 patients who presented with the syndrome of hypokalemic periodic paralysis as the symptom of thyrotoxicosis at Ratchaburi Hospital between January 1,1995 and December 31, 2007. Patients'data, diagnosis, blood chemistry, and thyroid function test were collected from medical records. RESULTS: All patients exhibited muscle weakness for a duration of one to two days, while all patients with hypokalemic periodic paralysis were determined to have high serum thyroid hormone and diagnosed with thyrotoxicosis. Patients with hypokalemic periodic paralysis were the first symptom leading to diagnosis of thyrotoxicosis. The attack of weakness occurred during the night in all patients. The patients, 96.6% being male, showed improvement of their symptoms through potassium replacement and thyrotoxicosis treatment using propylthiouracil and non selective beta adrenergic blocker All patients recovered and did not demonstrate reoccurring hypokalemic periodic paralysis. The degree of muscle weakness was found to correlate significantly (p < 0.05) with level of serum potassium, magnesium, and duration of weakness. CONCLUSION: It is important to determine blood thyroid hormone in all patients with hypokalemic periodic paralysis.