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Hypokalemia
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.
The earliest clinical manifestations of hypokalemia
Hypokalemia is also relatively common in clinical settings. If the blood potassium level falls below 3.5 mmol, it indicates that the patient has hypokalemia. Clinically, this can affect related systems. For instance, patients may experience general weakness, nausea, vomiting, loss of appetite, and even disorientation. If the patient remains hypokalemic for an extended period, it can lead to arrhythmias, such as premature atrial and ventricular contractions. Once hypokalemia occurs, it must be actively managed by correcting the low potassium levels. Clinically, this can be done by administering potassium chloride sustained-release tablets via nasogastric feeding, as well as consuming potassium-rich vegetables and fruits.
How is hypokalemia tested?
Hypokalemia can be diagnosed by drawing 3-5ml of venous blood for biochemical and electrolyte tests. Patients with hypokalemia may experience weakness or even paralysis, hence it is crucial to actively treat by replenishing potassium. During potassium supplementation, it is also important to clarify the underlying cause of the hypokalemia in order to solve the issue from its root. Otherwise, merely supplementing potassium might result in recurring hypokalemia.
Why does hypokalemia cause alkalosis?
Hypokalemia can cause metabolic alkalosis because it leads to the intracellular movement of hydrogen ions. In hypokalemia, potassium shifts from the inside to the outside of the cell to compensate for the decreased serum potassium. As an exchange, hydrogen ions from the gastric fluid move into the cells, causing cellular alkalosis and intracellular acidosis. Additionally, due to potassium deficiency in the renal tubular epithelial cells, the potassium-sodium exchange decreases and the sodium-hydrogen exchange increases, leading to enhanced excretion of hydrogen ions and increased reabsorption of bicarbonate ions, resulting in hypokalemia-induced metabolic alkalosis, which needs to be promptly addressed clinically.
Why does hypokalemia cause abnormal acidic urine?
Hypokalemia is characterized by a reduction in the concentration of potassium ions in the extracellular fluid, which causes the transfer of three potassium ions from inside the cells to the outside, while two sodium ions and one hydrogen ion move from the outside to the inside of the cells. Due to the decreased concentration of hydrogen ions in the extracellular fluid, metabolic alkalosis can easily occur. At the same time, due to the reduction of blood potassium, the potassium-sodium exchange in the renal tubules decreases. Renal tubular cells secrete more hydrogen ions to exchange with sodium ions, and the reabsorption of bicarbonate ions increases, raising the pH value. This metabolic alkalosis increases the number of hydrogen ions inside the cells and the kidney's hydrogen secretion, thus making the urine acidic, often referred to as paradoxical aciduria.
Early electrocardiogram manifestations of hypokalemia
When hypokalemia occurs in the human body, it produces characteristic manifestations on the electrocardiogram (ECG) known as U waves. These so-called U waves appear as small waves at the tail end of the ST-T segment, often accompanied by a slight depression of the ST-T segment and mild changes in the T wave. If hypokalemia is severe, it can induce supraventricular arrhythmias, including premature ventricular contractions or first-degree atrioventricular block. In very severe cases, it may lead to life-threatening torsades de pointes, a type of ventricular tachycardia. Therefore, monitoring blood potassium levels and timely potassium supplementation are crucial for these patients to protect their health and safety.
How many days does hypokalemia need to be treated?
In the extracellular fluid of human cells, the concentration of potassium in the blood is 3.5 to 5.5 millimoles per liter. If the potassium level falls below 3.5 millimoles per liter, it is considered hypokalemia. The main causes of hypokalemia are insufficient intake and excessive excretion. The treatment duration for hypokalemia caused by different primary diseases varies. For mild hypokalemia, oral potassium supplements alone can correct the condition, but this generally takes about three to five days. For severe hypokalemia, intravenous potassium should be administered as soon as possible, preferably through a central venous line for fluid administration. At this time, the focus is on treating the underlying disease and timely supplementation of potassium ions. The duration of treatment may be relatively longer, and it is not possible to determine a specific timeframe.
What are the symptoms of hypokalemia?
When the body's blood potassium level falls below 3.5 millimoles per liter, it is called hypokalemia. Hypokalemia can cause adverse symptoms in multiple systems of the body, initially causing weakness and fatigue in the limbs, flaccid paralysis, sluggish and absent tendon reflexes, and in severe cases, respiratory difficulty. At the same time, hypokalemia can lead to a series of central nervous system damages, such as apathy, a blank stare, drowsiness, and confusion; it also causes nausea, poor appetite, abdominal distension, and intestinal paralysis among other adverse gastrointestinal phenomena. Additionally, it can lead to palpitations, and rapid atrial or ventricular arrhythmias, among other adverse phenomena. Therefore, it is crucial to provide timely and proper potassium supplementation and correction of blood potassium levels for patients with hypokalemia.
How to supplement potassium for hypokalemia
Hypokalemia generally has two common methods of potassium supplementation. The first is oral potassium supplementation, and the second is intravenous potassium supplementation. Oral potassium supplementation is the safest method, for example, taking potassium chloride sustained-release tablets orally, as well as potassium chloride injection solution orally, and eating more potassium-rich vegetables and fruits. The second method is intravenous potassium supplementation. For intravenous potassium supplementation, it is important to pay attention to the patient's urine output. If the patient's urine output is adequate, intravenous potassium supplementation can be appropriately performed, and the concentration of intravenous potassium supplementation should not exceed 0.3% to prevent arrhythmias caused by hyperkalemia. (Please use medications under the guidance of a doctor.)
How is hypokalemia diagnosed?
Hypokalemia refers to a blood potassium level below 3.5mmol/L. Clinically, it is mainly diagnosed through electrolyte tests and arterial blood gas analysis, which can confirm whether a patient has low potassium. After developing hypokalemia, patients may experience symptoms such as fatigue and limb weakness. At this point, treatment should include the oral administration of sustained-release potassium chloride tablets or intravenous infusion of potassium chloride, as well as advising the patient to consume potassium-rich vegetables and fruits to correct hypokalemia. Prolonged hypokalemia can lead to arrhythmia and even endanger the patient’s life. (Medications should be used under the guidance of a clinical doctor, according to the specific situation.)