An unusual cause of leg weakness


Ambreen Qayum, Darshi Sivakumaran, Kingston Hospital, Surrey


A 30 years old Asian male presented to AE with an acute onset of progressive muscle weakness and was subsequently unable to mobilise with complete paraplegia.


Initial investigations showed a raised Creatine kinase of 3600 u/L, lactate of 3 mmol/L and potassium of 3.4 mmol/L


His symptoms quickly resolved after an IV infusion of Hartmannís solution. Although his presentation seemed to be suggestive of hypokalemic periodic paralysis, subsequent history, examination and thyroid function test confirmed primary hyperthyroidism in keeping with thyrotoxic periodic paralysis


He was commenced on carbimazole and beta-blockers at his first presentation and remains well since this episode.


Learning points: Thyrotoxic periodic paralysis is an uncommon disorder characterised by simultaneous thyrotoxicosis, hypokalemia and paralysis. The presentation is similar to hypokalemic/familial periodic paralysis and can be easily overlooked unless it is considered and thyroid function tests are checked. Failure to identify thyrotoxic periodic paralysis can result in presentations and puts patients at risk of rebound hyperkalemia due to excessive potassium replacement.

We present the characteristic features of the condition, causes and treatment.