Diagnosis And Treatment Of Hyperkalemia in Patients With Chronic Kidney Disease

The kidney is an important organ that regulates potassium metabolism in the human body. The incidence of chronic kidney disease (CKD) in my country is as high as 10.8%. Many CKD patients are combined with different degrees of potassium metabolism imbalance, and hyperkalemia has become a common complication in CKD patients. Correct identification of acute and chronic hyperkalemia, timely treatment of potassium-lowering, and effective long-term management is an important issues we face.

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Changes in the definition of hyperkalemia

At present, the normal range of serum potassium in my country is defined as 3.5-5.5 mmol/L, while many foreign kinds of literature and guidelines have lowered the upper limit of the normal value of serum potassium to 5.0 mmol/L. The advancement of the diagnostic criteria of hyperkalemia is helpful for the early detection, early intervention, and early management of hyperkalemia in CKD patients.

Update on the concept of acute and chronic hyperkalemia

Hyperkalemia can be divided into two types, acute and chronic, according to the speed of serum potassium rise and the harm caused, and the treatment goals and measures of the two are different. If the serum potassium rises to 6.0 mmol/L or above in a short period of time, or the electrocardiogram changes caused by high potassium are critically ill and require emergency treatment, the purpose of treatment is to return the serum potassium to a safe level as soon as possible; Combining risk factors such as diabetes and cardiac insufficiency, or taking potassium-containing/potassium-retaining drugs for a long time is prone to recurrent hyperkalemia, which requires long-term preventive management.

Management of acute hyperkalemia

For patients with acute hyperkalemia, it is usually necessary to perform vital signs monitoring and electrocardiogram examination immediately. Regardless of whether there are changes in the electrocardiogram, it is recommended to use calcium to stabilize the myocardium immediately. using central venous access).

Other common emergency potassium lowering measures:

(1) Promote the transfer of potassium ions into cells. Intravenous injection of glucose and insulin promotes the transport of potassium ions into cells. The concentration and volume of glucose and the dose ratio of insulin need to consider the patient's heart function, urine volume, and blood sugar level, according to the ratio of 1 unit of insulin to eliminate 4g of glucose, such as adding 6 units of regular insulin to 500ml of 5% glucose for intravenous drip; Patients with volume overload can be given 40 ml of 25% glucose and 3 units of regular insulin as an intravenous bolus. Sodium bicarbonate and salbutamol sprays also promote the transfer of potassium ions into cells, but the effect is limited.

(2) Promote the excretion of potassium ions. For non-oliguric patients with stable blood volume, loop diuretics can be used to promote the excretion of potassium ions from the urine, and thiazide diuretics can also be used at the same time. Cation exchange resins (such as sodium polystyrene sulfonate, and calcium polystyrene sulfonate) and new potassium ion binders (such as Patiromer, sodium zirconium cyclosilicate) can reduce the absorption of potassium ions in the intestinal tract and promote its excretion from the feces. This reduces blood potassium. Sodium polystyrene sulfonate can also be administered rectally in addition to oral administration, while sodium zirconium cyclosilicate has a better taste and can be used for patients who are intolerant of oral sodium polystyrene sulfonate.

Hemodialysis or continuous renal replacement therapy (CRRT) can be used to lower potassium in patients with acute hyperkalemia who are ineffective in drug treatment, especially those with established vascular access for uremia. It should be noted that the significant decrease in the extracellular potassium ion concentration after the end of dialysis can induce the further release of intracellular potassium ions, and potassium-lowering treatment can prevent the rebound increase of serum potassium after the end of dialysis.

Long-term management of chronic hyperkalemia

Long-term management is emphasized for chronic hyperkalemia. The relationship between serum potassium level and mortality in CKD patients showed a "U"-shaped curve, and the mortality rate was the lowest when serum potassium was 4.0-4.5 mmol/L. This range can be used as the target for long-term serum potassium control in CKD patients. For chronic and repeated hyperkalemic CKD patients, especially those with diabetes mellitus and cardiac insufficiency, it is necessary to check whether they are receiving potassium-containing or potassium-storing drug therapy at the same time, including renin-angiotensin-aldosterone system antagonist (RAASi), Potassium-sparing diuretics, etc. If the use of RAASi can really benefit the patient, it needs to be combined with potassium-lowering drugs orally at the same time to avoid hyperkalemia.

Maintenance hemodialysis patients are at greater risk of developing hyperkalemia compared with non-dialysis patients with CKD. The 2016 DOPPS study reported that the prevalence of hyperkalemia in maintenance hemodialysis patients was 30–50%, and the mortality rate due to hyperkalemia in hemodialysis patients was as high as 3.1 × 103 persons/year. Data from some dialysis centers in my country show that 23% of patients with short dialysis intervals have serum potassium > 5.5 mmol/L, and 48% of patients with long dialysis intervals have serum potassium > 5.5 mmol/L, of which 10% of The patient's serum potassium was more than 6.5 mmol/L. One hour after the end of hemodialysis, the patient's serum potassium increased rapidly. Compared with the short dialysis interval, the prevalence of hyperkalemia in the long dialysis interval increased from 26.2% to 61.6%, and the prevalence increased by 2%. ? 4 times. In order to avoid the death of patients during interdialytic due to hyperkalemia, it is recommended that patients take potassium-lowering drugs during interdialytic to control the increase and fluctuation of serum potassium during interdialytic.

Medical staff should also strengthen the propaganda and education on a low-potassium diet, help patients identify high-potassium foods, and master cooking methods to remove potassium such as blanching and soaking.

Monitoring of serum potassium in patients with CKD

Timely monitoring of serum potassium is an important part of stabilizing serum potassium in patients with CKD. For CKD patients, if RAASi or potassium-storing diuretics are added or increased, it is recommended to review serum potassium within 1 to 2 weeks. Dialysis patients are recommended to review electrolytes every 1 to 3 months. If there is abnormal serum potassium in the past, it is recommended to increase the monitoring frequency to at least once a month.

In conclusion, there is still a long way to go in the management of serum potassium in patients with CKD. The threshold of the diagnostic criteria for hyperkalemia has moved forward to give medical staff more time to identify and deal with it. Reasonable and regular electrolyte monitoring for CKD patients, as well as the correct identification and treatment of acute and chronic hyperkalemia, are also important links in the management process.

for more information:ali.ma@wecistanche.com