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Hyperkalemia
What are the causes of hyperkalemia?
The first reason is the excessive intake or administration of potassium, which can lead to hyperkalemia. For example, consuming foods that are very rich in potassium, or intravenously infusing solutions containing potassium. Additionally, the use of potassium salts of penicillin can also cause hyperkalemia, as well as the transfusion of stored blood, which can easily lead to hyperkalemia. Besides excessive intake and administration of potassium, diseases related to reduced excretion can also cause hyperkalemia, such as the most common instances during acute or chronic renal failure, where patients are prone to hyperkalemia. Furthermore, patients with reduced adrenal cortex function, such as aldosterone deficiency or Addison's disease, are also prone to hyperkalemia. Additionally, the use of diuretics that inhibit potassium excretion, notably spironolactone—a potassium-sparing diuretic—can also cause an increase in blood potassium levels. Another reason is a change in potassium distribution, such as when potassium moves from inside the cells to the outside, which can easily lead to hyperkalemia. This is common in cases of tissue damage, such as muscle contusion, or electrical burns, and tissue hypoxia, which also can easily lead to a change in potassium distribution, causing an increase in extracellular potassium. If hemolysis occurs in a test tube, such as if the venipuncture takes too long, or in conditions like leukocytosis or severe shaking of the blood sample, these might also lead to hyperkalemia. (The use of medications should be under the guidance of a doctor.)
Why should calcium be supplemented for hyperkalemia?
When high potassium levels trigger ventricular automaticity, it is recommended to administer calcium to counteract its cardiotoxicity. This is because during hyperkalemia, the excitability of the myocardium significantly increases. Calcium ions do not affect the distribution of potassium inside and outside the cells, but they can stabilize the excitability of the heart. Therefore, even if a patient's blood calcium level is normal, calcium should be injected immediately when there is severe arrhythmia. Calcium ions only temporarily counteract the toxicity of potassium to the heart and do not reduce the concentration of potassium in the blood. Thus, they can only serve as a short-term emergency medication. (Medication should be used under the guidance of a doctor.)
Causes of Hyperkalemia
Common causes of hyperkalemia in clinical settings include: First, it is related to excessive intake. Generally, a high-potassium diet under normal kidney function does not cause hyperkalemia. It only occurs when there is excessive or rapid intravenous potassium supplementation, or when kidney function is impaired. Second, hyperkalemia caused by reduced excretion. Common reasons include renal failure, lack of adrenocortical hormones, and primary renal tubular potassium secretion disorders, all of which can cause hyperkalemia. Third, a large transfer of potassium ions from inside the cells to the outside can also cause hyperkalemia.
How should hyperkalemia be managed?
First, it is necessary to assess the severity of the hyperkalemia, whether it is mild, moderate, or severe. For mild hyperkalemia, it can be managed by taking oral diuretics or intravenous infusion of glucose with insulin, which can normalize the potassium level. In cases of severe hyperkalemia, where blood potassium exceeds 7.5 mmol/L, there is a risk of causing cardiac arrest. Emergency measures to promote potassium excretion are required, such as hemodialysis or peritoneal dialysis. It is also necessary to counteract the myocardial depressive effects of potassium, which can be managed with the injection of calcium gluconate, along with the intravenous infusion of hypertonic glucose and insulin. (The use of medications should be conducted under the guidance of a doctor.)
Can hyperkalemia be cured?
The main focus is on the cause of hyperkalemia. If hyperkalemia is due to consuming foods rich in potassium, administration of potassium-containing solutions, transfusion of stored blood, use of potassium-sparing diuretics like spironolactone, or prolonged venipuncture causing severe shaking of the blood sample during transport, addressing these causes can prevent the occurrence of hyperkalemia. If hyperkalemia is caused by certain diseases, such as renal failure or adrenal insufficiency, active treatment of the underlying disease is required. If the renal failure is acute, recovery of kidney function might prevent the recurrence of hyperkalemia. However, if there is chronic renal insufficiency, there tends to be a higher recurrence rate of hyperkalemia. Therefore, whether hyperkalemia can be cured largely depends on identifying the underlying cause.
The impact of hyperkalemia on the heart
The effects of hyperkalemia on the heart mainly manifest in the following ways: First, it affects the excitability of the myocardium, as hyperkalemia can cause reduced or even absent myocardial excitability; second, it impacts myocardial conductivity. In hyperkalemia, due to the reduced resting potential, the amplitude and speed of the action potential's phase zero decrease, leading to slowed excitability spread and reduced conductivity; third, it influences the automaticity of the myocardium. In hyperkalemia, due to slowed automatic depolarization, the automaticity is reduced. Additionally, hyperkalemia produces characteristic changes in the electrocardiogram, such as depression or disappearance of the P wave, prolongation of the PR interval, widening of the S wave, and narrowing and peaking of the T wave, which are the main changes in the electrocardiogram due to hyperkalemia.
Principles of treatment for hyperkalemia
First, to counteract the cardiac inhibitory effects of potassium, calcium salts can be injected, and sodium bicarbonate can be used to alkalinize the blood. Then, an infusion of hypertonic glucose and insulin can be administered to promote the internal movement of potassium ions. Secondly, to promote the excretion of potassium, diuretics can be used. The second method involves the use of cation exchange resins and sorbitol. The third method employs dialysis therapy, which can include both hemodialysis and peritoneal dialysis. The fourth method is to reduce the sources of potassium, stop a high potassium diet or the use of potassium-containing drugs. In cases of severe hyperkalemia, where there is a life-threatening emergency, urgent measures should be taken, primarily the intravenous administration of calcium ion antagonists to counteract the cardiac toxicity of potassium. In cases of severe arrhythmias or even cardiac arrest, emergency installation of a pacemaker or defibrillation can be carried out, and respiratory muscle paralysis may require ventilatory support. (Medication use should be under the guidance of a doctor)
Hyperkalemia
Typically, when serum potassium exceeds 5.5 mmol/L, it is referred to as hyperkalemia. However, an increase in serum potassium does not necessarily reflect an overall increase in body potassium; serum potassium can also rise when there is a deficiency of total body potassium. Therefore, in clinical practice, serum potassium is evaluated in conjunction with an electrocardiogram and medical history to determine if a patient has hyperkalemia. Hyperkalemia is an important emergency in internal medicine and can often lead to sudden cardiac arrest. It should be identified and prevented early.
Mild hyperkalemia clinical manifestations
When blood potassium exceeds 5.5 millimoles per liter, it is referred to as hyperkalemia. Clinically, mild manifestations of hyperkalemia commonly involve the cardiovascular system, including bradycardia, audible enlargement of the heart, and weakened heart sounds. The electrocardiogram may show a shortened QT interval and peaked T waves. Symptoms related to the neuromuscular system include numbness in the lips and limbs, muscle soreness, and, in severe cases, paralysis of the respiratory muscles, which can lead to suffocation. All cases of hyperkalemia present various degrees of metabolic acidosis or azotemia, among other symptoms.
Clinical manifestations of hyperkalemia
The clinical manifestations of hyperkalemia are not specific. Early symptoms often include numbness in the limbs, sensory abnormalities, extreme fatigue, and muscle pain. In severe cases, there can be difficulties in swallowing, speaking, and breathing, paralysis of the limbs, and tendon reflexes may disappear. The central nervous system may show signs of restlessness, fainting, and confusion. Some may experience a slow heart rate, ventricular fibrillation, and in the most severe cases, it can lead to cardiac arrest. Other symptoms may include nausea, vomiting, diarrhea, and other gastrointestinal symptoms.