Hypokalemia is a lower than normal amount of potassium in the blood. Potassium is one of the main electrolytes and it is concentrated within the cells of the human body. As only 2% of the body's total potassium is available in the blood stream, even small changes in the serum levels of potassium tends to affect the body function. If the serum potassium level falls, muscles and nerves of the body are particularly affected.
How hypokalemia occurs
Normal potassium level when measured in the serum ranges from 3.5 to 5.0 mEg/liter. A normal intake of potassium daily is about 70 -100 mEq and the kidney is required to remove the same amount each day. In case more is removed, the body's total potassium store will be decrease. The result is hypokalemia, that is, hypo = low, kal= potassium, emia= in the blood occurs.
Symptoms of hypokalemia
Breakdown of muscle fibers, 'rhabdomyolysis', causes muscle weakness or spasms, muscle aches and muscle cramps.
Potassium affects the way neuromuscular cells discharge energy and consequently when the level falls, the cells cannot 'repolarize' and they are unable to fire repeatedly.
There could be changes in electrocardiogram findings (EKG or ECG) especially in the repolarization section of the EKG as heart is also a muscle. Irregular heartbeats 'palpitations' may also be perceived. In severe cases, hypokalemia can lead to dangerous disturbances in heart rhythm 'arrhythmia' or abnormal heart rhythms 'dysrhythmias'. Other symptoms of low potassium are:
- Paralysis which may include the lungs
- Tingling or numbness
- Nausea or vomiting
- Abdominal bloating
Patients with hypokalemia tend to pass large amounts of urine and feel thirsty most of the time. While a small drop in potassium does not cause symptoms, a big drop in the level can be life threatening.
Causes of hypokalemia
There could be several causes for low potassium occurrence in the body. Some common causes are:
- Use of water pills or diuretics
- Chronic laxative abuse
- There could be loss of potassium through stomach and intestines. These could be by way of vomiting, enemas or excessive laxative use and ileostomy operation.
- Illness and other medications used for asthma or emphysema, steroids or theophylline and aminoglycosides.
- Disorders in the kidney such as renal tubular acidosis leading to chronic kidney failure.
Magnesium deficiency and leukemia cause hypokalemia.
- Use of insulin
- Certain metabolic states such as alkalosis which are used for shifting potassium across cells can lower the concentration of potassium measured in the blood.
- Eating disorders such as bulimia
- Eating large amounts of licorice or using products such as herbal teas and chewing tobaccos that contain licorice made with glycyrrhentic acid
- Decreased food intake or malnutrition
Diagnosis of low potassium
A health provider normally takes blood samples of the patient and checks for potassium levels. Other tests include:
- Arterial blood gas
- BUN and serum creatinine level
- Blood tests to estimate the levels of glucose, magnesium, calcium, sodium, phosphorous, thyroxine and aldosterone levels.
Hypokalemia can also be a secondary problem which could be part of the evaluation for an underlying disease. For instance, if a patient with high blood pressure is treated with diuretics, the potassium levels are also monitored. Patients exhibiting vomiting and diarrhea, dehydration and weakness may have their electrolytes tested in order to determine whether body potassium losses may need to be replaced.
Treatment for hypokalemia
Mild hypokalemia may be treated by intake of potassium supplements by way of mouth. Serum potassium levels above 3.0 mEq/liter is not considered dangerous or of great concern. Potassium rich foods include fresh fruits like bananas, oranges, strawberries, avocados and apricots, fresh vegetables like greens, mushrooms, peas, beets and tomatoes, meats like beef, fish and turkey and juices like orange, apricot and grape fruit.
Persons with severe deficiency may need to get potassium intravenously. When potassium needs to be given intravenously, it has to be given slowly. Potassium is irritating to the vein and must be given at a rate approximately 10mEq/liter per hour. Infusing potassium too quickly can cause heart irritation and promote potentially dangerous rhythms ventricular tachycardia.
A type of hypokalemia can cause paralysis when there occurs too much of thyroid hormone in the blood 'thyrotoxic periodic paralysis.' Treatment lowers the thyroid hormone level and raises potassium level in the blood.
Very rarely, a critical situation can occur when the potassium in the body shifts from the serum into the cells of the body. This drops the serum potassium levels to 1.0 mEq/liter or even lower. This can cause immediate muscle weakness and the patient cannot move. In such case, treatment of potassium replacement intravenously is effective and recovery occurs within 24 hours.
Prevention of hypokalemia
Potassium is essential for the cells, especially nerve and muscle cells and she can get potassium through food. It should be remembered that hypokalemia is a metabolic disorder that occurs when the level of potassium in blood drops too low.
Hence, eating a rich and well balanced diet helps prevent low potassium conditions. Foods high in potassium include bananas, bran, Brussels sprouts, granola, kiwi, lima beans, milk, oranges, peaches, peanut butter, peas and beans and tomatoes.
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