Potassium
Potassium is a mineral that controls nerve and muscle function. One very important muscle—the heart—beats at a normal rhythm because of potassium. In addition potassium is necessary for maintaining fluid and electrolyte balance and pH level. In order for potassium to perform these functions, blood levels must be kept between 3.5 and 5.5 mEq/L. The kidneys help keep potassium at a normal level. Potassium levels that are too high or too low can be dangerous.
Potassium comes from the foods we eat. Healthy kidneys remove excess potassium in the urine to help maintain normal levels in the blood. Since most foods have potassium, low potassium (hypokalemia) is uncommon in people who eat a healthy diet. Poor food intake, excessive vomiting and diarrhea and taking certain medications, such as diuretics, can cause low potassium levels.