When serum (blood) potassium levels are low, this condition is called hypokalemia. Since the typical Western diet contains plenty of potassium, the chance of having hypokalemia if you are a healthy adult on no medication is less than 1 percent. Hypokalemia is more likely if you are taking certain diuretics or glaucoma medications, or if you have certain medical conditions, such as hyperaldosteronism or diseases affecting the kidneys. A person can have hypokalemia with no symptoms or with severe symptoms. Left untreated, symptoms usually become worse and can lead to death. It can be difficult to differentiate between symptoms of hypokalemia and complications of hypokalemia.
Hypokalemia can cause irregular heartbeats, known medically as cardiac dysrhythmias. The heartbeat may be unusually fast, a condition called tachycardia. Severe dysrhythmias can lead to cardiac arrest and lung paralysis. Severe vomiting and diarrhea in small children, which leads to fluid loss and hypokalemia, can cause cardiac arrest. Hypokalemia can also cause high blood pressure or hypertension.
Hypokalemia can cause fatigue. A person may experience muscle weakness, cramping and muscle pain (myalgia). Reduced blood flow to the skeletal muscles caused by hypokalemia can lead to rhabdomyolysis, a condition in which the muscle fibers break down. Hypokalemia can lead to paralysis, affecting the legs more frequently than the arms, although that complication is uncommon.
Diabetic patients with hypokalemia frequently have hyperglycemia, or high blood sugar levels. Hypokalemia interferes with the release of insulin and with the body's sensitivity to insulin. Controlling and treating hypokalemia can help reduce hyperglycemia and the diabetic complications it brings.
A person may find himself unusually thirsty if he has hypokalemia. He may experience constipation. He may find himself urinating frequently or passing large amounts of urine, a condition called polyuria. Hypokalemia can also lead to metabolic acidosis, respiratory acidosis, renal cystic disease and hepatic encephalopathy.