Potassium deficiency can cause an irregular heartbeat, says MedlinePlus. Other symptoms include heart palpitations, tiredness, constipation and numbness or tingling. The patient may also suffer damage to his muscles, weak muscles or muscles that go into spasm.
Potassium is an element the body needs to help its cells work the right way, says MedlinePlus. It's also an electrolyte, according to Healthline. This means it carries an electrical charge. When there is not enough of it, a system that relies on electrical activity, such as the heart, can't function properly.
Potassium deficiency, or hypokalemia, can be caused by kidney disease, alcoholism, bulimia, excess use of laxatives and diuretic medications, says MedlinePlus.