Hypokalemic paralysis in a young obese female

Profound hypokalemia with paralysis usually poses a diagnostic and therapeutic challenge.

We report on a 28-y-old obese Chinese female presenting with sudden onset of flaccid quadriparesis upon awaking in the morning. There is no family history of hyperthyroidism. She experienced body weight loss of 7 kg in 2 months.

The most conspicuous blood biochemistry is marked hypokalemia (1.8 mmol/l) and hypophosphatemia (0.5 mmol/l) associated with low urine K(+) and phosphate excretion. Surreptitious laxatives and/or diuretics abuse-related hypokalemic paralysis were tentatively made. However, her relatively normal blood acid-base status and the absence of low urine Na(+) and/or Cl(-) excretion made these diagnoses unlikely. Furthermore, she developed rebound hyperkalemia (5.7 mmol/l) after only 80 mmol K(+) supplementation. Thyroid function test confirmed hyperthyroidism due to Graves' disease. Control of the hyperthyroidism completely abolished her periodic paralysis.

Thyrotoxic periodic paralysis (TPP) should be kept in mind as a cause of paralysis in female, even with obesity, despite its predominance in adult males.