OVERVIEW
The concentration of potassium in human serum is only 3.5 to 5.5 mmol/L, but it is essential for life activities. The main role of potassium in the body is to maintain acid-base balance, participate in energy metabolism and maintain normal neuromuscular function. When there is a lack of potassium in the body, it will cause general weakness, fatigue, weakened heartbeat, dizziness, and severe potassium deficiency will also lead to respiratory muscle paralysis and death. In addition, low potassium will slow down gastrointestinal peristalsis, leading to intestinal paralysis, aggravated anorexia, nausea, vomiting, abdominal distension and other symptoms.
Causes
1. Decreased potassium intake
General diet is rich in potassium, so as long as you can eat normally, your body will not be deficient in potassium. Patients with gastrointestinal obstruction, coma, and long time fasting after surgery cannot eat. If these patients are not supplemented with potassium at the same time when nutrition is fed into the vein or the potassium supplementation is not enough, it can lead to potassium deficiency and hypokalemia. If insufficient intake is the only cause, the degree of potassium deficiency can be relieved within a certain period of time because of the potassium conserving function of the kidney. When potassium intake is insufficient, the urinary potassium excretion can be reduced to less than 20 mmol/L within 4-7 days, and then to 5-10 mmol/L within 7-10 days (the urinary potassium excretion is 38-150 mmol/L in normal).
2. Excessive potassium excretion
(1) Loss of potassium through the gastrointestinal tract This is the most important cause of potassium loss in children, and is common in patients with severe diarrhea and vomiting accompanied by large amounts of digestive fluid loss.
(2) Loss of potassium through the kidney This is the most important cause of potassium loss in adults. The common factors causing the increase of potassium discharge from the kidney are: (1) long-term continuous use of diuretics or excessive dosage; (2) certain renal diseases; (3) excessive adrenocorticotropic hormone; (4) increase of anions not easily reabsorbed in the distal tubule; (5) magnesium deficiency; and (6) alkalosis.
(3) Transdermal potassium loss
3. Transfer of extracellular potassium to intracellular tissue
Hypokalemia may occur when extracellular potassium is transferred into the cell, but the total amount of potassium in the body does not decrease.
Symptoms
Potassium deficiency reduces muscle excitability, preventing smooth contraction and relaxation of muscles and making them easily tired. In addition, it can hinder intestinal peristalsis and cause constipation; it can also lead to heart attacks. When the body’s potassium intake is insufficient, sodium will carry a lot of water into the cells, making the cells edema leading to cell rupture. Lack of potassium in the blood will make blood sugar high, leading to hyperglycemia. In addition, potassium deficiency causes the most serious damage to the heart, and a lack of potassium is probably one of the leading causes of death from heart disease in humans.
When there is a lack of potassium in the body, it can cause general weakness, fatigue, arrhythmia, dizziness, and severe potassium deficiency can lead to death from respiratory muscle paralysis. In addition, low potassium will slow down gastrointestinal peristalsis, leading to intestinal paralysis, aggravated anorexia, nausea, vomiting, abdominal distension and other symptoms.
Examination
1. Blood test indicators
Decrease in serum potassium concentration <3.5mmol/L, blood pH at the high limit of normal or >7.45, sodium ion concentration at the low limit of normal or <135mmol/L.
2. Urine laboratory indicators
Urine potassium concentration is reduced, urine pH is acidic, and urine sodium excretion is high.
3. Electrocardiogram
The earliest manifestations are ST-segment depression, T-wave depression, widening, inversion, δ-wave, Q-T time prolongation, and the above changes can be improved after potassium supplementation.
Diagnosis
1. Prolonged fasting or scanty eating, vomiting, diarrhea, prolonged use of diuretics without potassium supplementation.
2. Weakness, decreased tendon reflexes, apathy, drowsiness, abdominal distension, myasthenia gravis, palpitations, arrhythmias and other clinical manifestations.
3. Serum potassium <3.5 mmol/L.
4. Electrocardiogram showing T-wave hypoplasia, bi-directionality, inversion or presence of U-wave.
Treatment
The prevention and treatment of low potassium is based on the treatment of the cause of the disease and potassium supplementation. Clinically, a certain amount of 10% potassium chloride solution can be added into oral or intravenous rehydration solution. Eating more potassium-rich foods is also a safe and effective method, especially eating more fruits and vegetables. Potassium-rich fruits include bananas, strawberries, oranges, grapes, grapefruit, watermelon, etc. Spinach, yam, beans, amaranth, scallions and other vegetables are also rich in potassium; soybeans, mung beans, fava beans, kelp, seaweed, purple seaweed, yellow fish, chicken, milk, cornmeal and so on, also contain a certain amount of potassium. Various fruit juices, especially orange juice, are also rich in potassium and can replenish water and energy.