Unusual causes of hypokalaemia and paralysis.

We demonstrate how the application of physiological principles may help to identify unusual causes of a very low plasma potassium (K+) concentration (P(K)) and paralysis. In the two patients described, the short time course of the illness suggested that there was an acute shift of K+ into cells. The combination of a low rate of excretion of K+, the absence of a metabolic acid-base disorder, and the fact that the clinical findings occurred very soon after a large intake of carbohydrate supported this impression. Surprisingly, the P(K) remained low for many hours after these stimuli to shift K+ into cells had abated. The missing link in this story was eventually provided by the attending medical team with the help of their mentor, Professor McCance.