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Hyperkalemia
The impact of hyperkalemia and hypokalemia on acid-base balance
Both hyperkalemia and hypokalemia have adverse effects on the body's acid-base balance. In hypokalemia, the concentration of potassium in the extracellular fluid decreases, causing potassium to move from inside the cells to the extracellular fluid, while hydrogen ions move into the cells. The lack of potassium in the tubular epithelial cells of the kidney also leads to an increased secretion of hydrogen ions; hence, sodium-hydrogen exchange increases, and the reabsorption of bicarbonate is enhanced, resulting in metabolic alkalosis. Conversely, hyperkalemia can cause metabolic acidosis, as an increase in extracellular potassium causes potassium to move into the cells, while hydrogen ions in the cellular fluid move out. At the same time, an increased potassium concentration inside the tubular epithelial cells leads to metabolic acidosis.
Can hyperkalemia be cured?
Hyperkalemia is treatable. The first cause of hyperkalemia is an excess of potassium, mainly seen in reduced renal excretion and excessive potassium intake, such as the infusion of a large volume of stored blood. In this case, diuretics can be used to increase the excretion of potassium. For cases of excessive potassium intake and excessive transfusion of stored blood, treatment options include diuresis and the use of glucose with insulin to lower potassium levels, or even treatment with sodium bicarbonate. In cases of shift hyperkalemia, primarily seen in hemolysis and septic shock, dialysis can be used to reduce hyperkalemia while simultaneously treating the underlying disease. The third type is concentration hyperkalemia and severe hemorrhagic shock, which causes a reduction in blood volume leading to blood concentration and relative hyperkalemia. Treatment of the primary disease first is advisable, and typically, the high blood potassium can self-correct after the primary disease is cured. There is also a condition known as pseudohyperkalemia, for example, prolonged storage of drawn blood can cause hemolysis within the tube, poor venipuncture technique, thrombocytosis, and leukocytosis can all lead to pseudo-hyperkalemia. In these cases, re-drawing blood multiple times to verify the potassium levels can address this issue. Therefore, hyperkalemia is treatable.
Hyperkalemia presents with what symptoms?
Early signs of hyperkalemia often manifest as abnormal numbness in the limbs, extreme fatigue, muscle soreness, pallor and clamminess of limbs, and in severe cases, there may be difficulties in swallowing, speaking, and breathing, and even ascending paralysis and disappearance of tendon reflexes. The central nervous system may be affected, presenting as restlessness, fainting, and even confusion. The heart is often a major organ damaged by hyperkalemia, which can lead to a slowed heart rate. Patients may experience palpitations and panic among other discomforts, and in the most severe cases, it can cause cardiac arrest. Other symptoms may include nausea, vomiting, and abdominal pain, among other gastrointestinal symptoms.
Why does hyperkalemia cause muscle weakness?
The muscles that govern movement in our body are striated muscles, and each muscle cell in striated muscles has many receptors, which we can think of as a signal receiving and transmitting station. When we need to move, the brain nerves will send a signal to this station, which then controls muscle movement. A very important ion in muscle movement is the calcium ion. There is a receptor for calcium ions on our muscle cells, and it is related to the concentration of blood potassium. When the concentration of blood potassium is too low, a condition known as hypokalemia, or too high, known as hyperkalemia, the calcium ion receptor will be inhibited. At this point, our muscles will exhibit symptoms of muscle weakness.
What should be noted in the diet for hyperkalemia?
In cases of hyperkalemia, it is important to avoid eating foods high in potassium, such as corn, lettuce, carp, eel, lamb, beef, pork, as well as dates, bananas, and others. These foods are rich in potassium and should be consumed less or not at all. Additionally, a diet high in sugar and fat should be provided, or some intravenous nutrition may be used, to ensure sufficient caloric intake and prevent the release of potassium from metabolic breakdown, which could lead to an increase in blood potassium levels. Also, it is important to avoid certain medications high in potassium, such as traditional Chinese medicines. (Medication use should be under the guidance of a professional doctor.)
What are the changes in urine output in hyperkalemia?
When patients experience hyperkalemia, urine output generally decreases, leading to reduced potassium excretion by the kidneys, typically accompanied by abnormal kidney function. Thus, as long as kidney function is normal and daily urine output exceeds 500 milliliters, hyperkalemia is usually rare. Some causes of reduced renal potassium excretion include decreased glomerular filtration rates and reduced potassium secretion by the renal tubules, commonly seen in acute and chronic renal failure, adrenal cortex insufficiency, low renin, low aldosterone blood conditions, renal tubular acidosis, and long-term use of diuretics, especially potassium-sparing diuretics. Additionally, β-adrenergic tissue agents and angiotensin-converting enzyme inhibitors can cause drug-induced hyperkalemia, leading to abnormal kidney function and, consequently, decreased potassium excretion by the kidneys, ultimately resulting in reduced urine output.
Causes of hyperkalemia
The causes of hyperkalemia may include: First, excessive intake, such as consuming too much high-potassium food, medications with high potassium content, including some traditional Chinese medicines, potassium penicillin, stored blood, and excessive potassium supplementation. Second, it could be due to decreased potassium excretion by the kidneys. When renal insufficiency, acute or chronic renal failure occurs, it is often accompanied by severe hyperkalemia. Third, there is also decreased potassium secretion by renal tubules. When there is a deficiency of corticosteroids, there can be degenerative, asymptomatic hyperkalemia. Hyperkalemia can also occur when renal tubules are insensitive to aldosterone. Fourth, medications that reduce potassium excretion, such as the use of potassium-sparing diuretics, angiotensin-converting enzyme inhibitors, other nonsteroidal anti-inflammatory drugs, cyclosporine, etc., can also cause hyperkalemia. Fifth, the shift of potassium from inside the cells to the extracellular fluid, which can be caused by tissue damage, hypoxia, or the use of certain medications, leading to hyperkalemia.
What medication is used for hyperkalemia?
Hyperkalemia is primarily treated by promoting diuresis to enhance the elimination of potassium, while calcium gluconate can also be administered intravenously to counteract the inhibitory effects of potassium on the heart. Additionally, concentrated glucose with insulin can be used to shift excess potassium ions from the blood. Sodium bicarbonate can also be used to alkalinize the blood's pH to help reduce potassium levels. All these treatments must be conducted safely. In cases of severe hyperkalemia, dialysis may be necessary. If arrhythmias, bradycardia, or myocardial depression occur, the installation of a temporary pacemaker, along with hemodialysis, may be required. (Medication should be administered under the guidance of a physician.)
How to treat vomiting caused by hyperkalemia?
For patients with hyperkalemia, early symptoms include numbness in the limbs, weakness, muscle soreness, and paralysis. As the condition progresses, it can suppress myocardial function, reducing the tension of the myocardium and leading to slow heartbeats, and even cause arrhythmias and cardiac arrest. Increased release of acetylcholine can also cause nausea, vomiting, abdominal pain, and other symptoms. Patients with this condition generally also exhibit symptoms of hyperlipidemia and metabolic acidosis. For mild cases of hyperkalemia, temporary treatment may not be necessary, and symptomatic treatment such as stopping vomiting and drinking water may be sufficient. However, in acute cases, it is recommended that the patient immediately undergo dialysis or receive diuretic injections to rapidly eliminate potassium ions from the body, and to stop consuming foods and medications that contain potassium.
Does hyperkalemia cause a fast or slow heart rate?
Hyperkalemia often causes a slowed heart rate and is associated with various arrhythmias. When serum potassium is between 6.6 to 8.0 mmol/L, tented T-waves may be observed. When serum potassium levels rise rapidly, it can lead to ventricular tachycardia or even ventricular fibrillation. On the other hand, a slow increase in serum potassium can cause conduction blocks, and in severe cases, may lead to cardiac arrest. These are the heart rate changes caused by hyperkalemia, which typically result in a slower heart rate.