Hypokalemia (potassium deficiency) is a condition of the low level of potassium in the body.
Hypokalemia is an electrolyte imbalance when the level of potassium is lower than it should be.
Potassium is one of the most important minerals in the human body. Most of the body potassium is stored within the cells (98%). Along with sodium they regulate the transport of different minerals through the cell membrane (due to the so called Na+/K+ pump and concentration gradient). Potassium is especially important for the muscle and nerve activity.
The normal potassium level is 3.5-5.0 mmol/L. When the level of serum potassium is under 3.5 mmol/L it is considered to be hypokalemia.
Causes and risk factors
The condition may develop due to excessive loss of the potassium with the urine caused by diuretics. Vomiting and diarrhea are also known to reduce the levels of serum potassium.
Hypokalemia is common for people with eating disorders (bulimia, anorexia nervosa), those who suffer from AIDS and alcoholismus.
Other causes of low potassium may be the following:
- Chronic kidney disease;
- Diabetic ketoacidosis;
- Alkalosis (an increase in the pH of the blood);
- Intake of steroids;
- Excessive laxative use;
- Excessive sweating;
- Folic acid deficiency;
- Magnesuim deficiency;
- Pancreatic fistula;
- Villous adenoma (a colon polyp);
- Tubulo-interstitial renal disease;
- Primary hyperaldosteronism;
- Cushing’s syndrome;
- Some antibiotic use;
- Bartter syndrome or Gitelman syndrome – hereditary defects of renal salt transporters may cause hypokalemia;
- Hypokalemic periodic paralysis is a rare hereditary condition characterized by the episodes of hypokalemia accompanied by muscle weakness or paralysis;
In extremely rare cases hypokalemia can be caused by the insufficient dietary intake of potassium.
Recommended daily intake and the sources
Normal daily intake of potassium is 270 – 390 mg/dL.
Potassium-containing foods include:
- meats such as beef, fish and turkey;
- leafy green vegetables;
- baked potatos;
- coconut water;
- citrus fruits;
According to the level of serum potassium hypokalemia is classified as
- Mild – 3.1-3.5 mmol/L;
- Moderate – 2.5-3.0 mmol/L;
- Severe – <2.5 mmol/L;
Usually mild hypokalemia is asymptomatic.
In more severe cases the following symptoms may occur:
- Muscle pain, weakness, tiredness, or cramping in arm or leg muscles, sometimes so severe that causes inability to move arms or legs due to weakness, paralysis at first begin in the lower limbs, then progress to the upper extremities and torso;
- Tingling or numbness;
- Nausea or vomiting;
- Loss of appetite;
- Abdominal cramping, bloating;
- Palpitations (feeling of the irregular heart beat);
- Polyuria (passing large amounts of urine) or polydipsia (feeling very thirsty most of the time);
- Bradycardia (abnormally slow heartbeat);
- Arterial hypotension (low blood pressure) that causes fainting;
- Cramps and tetany;
- Psychological symptoms: depression, psychosis, delirium, confusion or hallucinations;
- Respiratory depression;
See also: Iodine deficiency
Blood test is performed to measure the level of potassium. Other test include measurement of glucose, magnesium, calcium, sodium, phosphorous, thyroid hormone and aldosterone levels.
There are specific electrocardiogram (EKG, ECG) changes associated with hypokalemia.”U” waves could be seen on EKG. In severe cases, hypokalemia can disturb the heart rhythm (causing dysrhythmia).
A very low potassium level (less than 2.5 mmol/L) can be life-threatening and requires urgent medical attention.
Potassium replacement therapy is based on the severity of the symptoms and person’s condition. For every 1 mEq/L decrease in serum potassium, the potassium deficit is approximately 200-400 mEq.
The first step in the treatment of hypokalemia is to eliminate the underlying cause of electrolyte imbalance.
When the level of potassium is severely low intravenous therapy should be started immediately. Potassium is usually administered at a maximal rate of 10 mEq/hour.
When hypokalemia is mild or moderate oral replacement is recommended. Common doses are 10-20mEq /day.
Other medications are administered to reduce the symptoms of the disorder.