Recurrent paralysis in a young man

Abstract

Listen

Translate article

A 22-year-old man presented in July, 1997, with 1 day history of weakness of both legs that progressed to involve his arms over a few hours. He was breathless, with no sensory abnormalities or sphincter involvement. He had had more than 200 similar episodes of weakness over the past 9 years, requiring multiple admissions. He had hypokalaemia during at least five admissions. He was diagnosed with hypokalaemic periodic paralysis (HOPP). Every time he became weak he would treat himself with potassium chloride, and the weakness would respond. He denied any precipitating factors. Previously he had been given acetazolamide, but he stopped taking this drug because it increased episodes of weakness. On examination he was drowsy, irritable, cyanosed, with grade 2 motor quadriparesis. Respiratory rate was 56/min with chest expansion of 0·5 cm. There were no signs of meningeal irritation or cranial nerve, sensory, cortical, or sphincter involvement. Full blood count was normal. The serum sodium was 136 mmol/L, potassium 1·8 mmol/L, chloride 112 mmol/L, and bicarbonate 9·2 mmol/L. Arterial blood gas analysis showed pH 7·26, a PaO2 of 23·3 mm Hg with an O2 saturation of 76·9%. Urine pH was 7·0, dipstick was negative for protein and glucose and microscopy was normal. The serum concentrations of urea, creatinine, glucose, uric acid, calcium, phosphate, liver function tests, creatinine kinase, and lactose dehydrogenase were normal. The patient was ventilated and potassium chloride and sodium bicarbonate were given. He had a rapid recovery over the next 24 hours. Urine pH remained alkaline. 24-hour excretion of phosphate, uric acid, and calcium was normal. There was no aminoaciduria or glycosuria. Urinary sodium was 43·2 mmol/L, potassium 32·6 mmol/L, chloride 69 mmol/L. Fractional excretion of bicarbonate at induced serum bicarbonate of 21·2 mmol/L (after a bicarbonate infusion) was 3·2% and U-B pCO2 11·2 mm Hg. Serum and urinary osmolality were normal. Radiographs of the chest, and bones showed osteopenia. Electrocardiogram showed U waves initially which became normal after correction of serum potassium. Radiological examination of the kidneys were normal. Viral serology was negative. Thyroid function was normal. Nerve conduction studies were normal. Electromyography showed a diminution of interference pattern. The patient was discharged on oral sodium bicarbonate and potassium chloride, when his pH was 7·34 with bicarbonate of 19·2 mmol/L. Over the next 2 years, he had only two episodes of weakness, each brought about by discontinuation of the therapy, and both responded to reinstitution of potassium chloride and bicarbonate. A screen of the family members was negative for any acidification defect.