Low plasma potassium level can cause muscle weakness, lassitude, constipation as well as rhabdomyolysis and arrhythmias, when severe. In muscle, low plasma potassium increases resting membrane potential (hyperpolarization) of myocytes that tend to make muscle more refractory to excitation, leading to muscle weakness. Hypokalemia can be associated with a myriad of causes including drugs of abuse...
