Post Date December, 03 2023
Potassium ion is one of the most important cations in the body, and its plasma concentration must be maintained within a certain range in order for the body to maintain normal function. Normal blood potassium concentration and the ratio of intracellular and extracellular potassium ions are decisive factors in maintaining neuromuscular stress. In addition, potassium ions are also involved in the regulation of various intracellular enzyme activities.
The total amount of potassium ions in the body is 3000-4000 mmol, of which more than 98% is distributed within cells (especially muscle cells), and about 1.4% is distributed outside cells, while the potassium ions in plasma only account for about 4% of the total amount. The normal intracellular potassium ion concentration is 140-150 mmol/L, and the extracellular (including plasma and interstitial fluid) concentration is 3.5-5.5 mmol/L. To maintain the balance of potassium in the body, it is first necessary to maintain a constant total amount of potassium ions.
The kidney is an important organ that regulates the concentration of plasma potassium ions. When excessive potassium is ingested, the kidney increases potassium excretion, while when potassium intake decreases, the kidney decreases potassium excretion to maintain plasma potassium concentration.
Under normal circumstances, people consume 70-120 mmol of potassium every day, of which about 90% is excreted through the kidneys, and the rest is excreted through feces and sweat. For patients with renal insufficiency, especially hemodialysis patients, they have lost the most important physiological regulation function of potassium ions in the human body, and the intake of potassium cannot be fully discharged, so they are prone to hyperkalemia. Hemodialysis patients have a basic loss of renal function and are at high risk of hyperkalemia.
Hemodialysis patients are prone to hyperkalemia when:.
Hemodialysis is one of the methods of renal replacement therapy, and one of its therapeutic purposes is to maintain electrolyte balance. Hemodialysis patients often have high blood potassium before dialysis, even higher than the normal high limit. The potassium concentration of dialysate used in hemodialysis is often lower than the plasma potassium concentration, so that the potassium in the plasma enters the dialysate side through the dialysis membrane of the dialyzer from the blood side and is eliminated. The lower the potassium concentration of dialysate, the stronger the potassium scavenging effect. However, it is not that the lower the potassium concentration in the dialysate, the better. When the potassium concentration in the dialysate drops too low, it may lead to hypokalemia after dialysis, or the blood potassium drops too quickly during dialysis, which is unsafe.
Insufficient dialysis is another important cause of hyperkalemia. Some patients cannot arrive at the hospital for dialysis on time due to economic and other reasons, resulting in a long interval between two dialysis sessions; Or the patient cannot apply heparin when suffering from diseases such as gastrointestinal, cerebrovascular, and fundus hemorrhage, resulting in clogged filters and pipelines during hemodialysis. The above conditions can lead to inadequate dialysis, which means that uremic toxins cannot be fully cleared, and metabolic acidosis cannot be promptly corrected, leading to hyperkalemia.
Before entering dialysis, in order to slow down the progression of kidney disease, doctors will recommend strict dietary restrictions for patients. After entering hemodialysis, in order to maintain good nutritional status, doctors will also recommend "appropriate" calorie and energy intake for patients. If it is not "appropriate", it is more prone to hyperkalemia. Many patients with hypertension deliberately use low sodium salts in their daily lives in order to control sodium intake, but they are unaware that the content of potassium ions in low sodium salts is very high, resulting in a trade-off.
Some drugs can also cause hyperkalemia. After entering dialysis, many uremic patients will carefully choose angiotensin converting enzyme inhibitors or angiotensin II receptor antagonists, such as XX sartan and XX pril, to protect the heart, cerebral blood vessels, and other organs; And the aldosterone receptor antagonist spironolactone. Due to the pharmacological effects of these drugs themselves, hyperkalemia may occur in some patients with uremia. However, it is worth noting that we should use these drugs under the guidance of a doctor, rather than arbitrarily increasing the dose of these drugs, nor blindly refusing them due to concerns about hyperkalemia. In addition, some patients with severe anemia may also experience hyperkalemia after repeated infusion of outdated hematocrit. Some uremic patients also take traditional Chinese medicine decoction on their own in order to treat other concurrent diseases. Many Chinese herbal medicines have high potassium concentrations, which can also lead to high blood potassium.
In summary, on the basis of standardized hemodialysis treatment, if patients can learn more about the causes of hyperkalemia and regularly monitor them for prevention, hyperkalemia can be avoided.
