Hypokalaemic periodic paralysis in central Sri Lanka.

We describe 14 Sinhalese male patients with hypokalaemic periodic paralysis (HPP). The age at onset was between 10 and 32 years. Each paralytic episode lasted from 6 to 48 hours (except in one patient who had an attack lasting 5 days). The frequency of attacks varied from 8 to 10 per month in one patient to only 2 attacks over a period of 16 years in another. Four patients (28.6%) had a family history of the disease. Hypokalaemia (serum potassium 1.5 to 3 mmol/l) was documented during an attack in 11 patients. No cause for hypokalaemia was evident in any of them. Investigations including EMG, thyroid hormone level and skeletal muscle histology were within normal limits between episodes. All the patients responded well to treatment with potassium supplementation, alone or with acetazolamide.