Hyperkalemia in MRCP (2)

Hyperkalemia in MRCP (2)

OK, if you are currently working in any hospital around the world, you certainly agree with me that hyperkalemia always disturbs you a lot. I remember that when I was a house officer many years ago, I was once called by staff nurse because she was worried that patient may collapse simply because his Potassium level was 5.4!


I think the general principles of treating hyperkalemia are simple,

First,

You have to act fast to avoid cardiac arrhythmia.

Second,

To shift the Potassium back to the cell ( intracellular) from extracellular ( plasma) if possible.

Third,

To reduce total body Potassium

Fourth,

AND of course, find out the underlying cause of hyperkalemia.


I will not discuss how aggressive you want to treat hyperkalemia and I think it is a judgment call. Anyway, I would be certainly very worried if the Potassium level is more than 6.5 and there is ECG changes. ( Learn about hyperkalemia associated ECG changes, it is a popular question in MRCP).

So, treatment of hyperkalemia can be outlined as below,

I think the very first step to take is to stabilize the heart by giving Calcium gluconate or Calcium chloride. You may want to open your physiology book to learn the mechanism how Calcium acts.

Then ,of course, you want to try to shift back the Potassium back to the cell by giving insulin and glucose. In Malaysia, the combination of insulin, glucose and Calcium therapy in treating hyperkalemia is termed as cocktail regime!

You can also use beta agonist to shift the Potassium back to the cell. Another useful strategy is bicarbonate infusion. Remember, acidosis causes hyperkalemia, therefore alkalosis corrects hyperkaelmia.
Another strategy you may want to try is giving patient cation exchange resin. However, remember that the effect is not immediate, therefore, you have to use previous various strategies to bring down the Potassium level promptly.

Anyway, I must say the most powerful way of treating your hyperkalemia is haemodialysis!!

Hyperkalemia in MRCP (1)

Hyperkalemia in MRCP – Part 1

Electrolyte imbalance is an important topic in MRCP and I think Potassium is the single most important electrolyte in our bodies.

If you are a house officer, I think the commonest electrolyte abnormality you will see in medical ward is hypo/hyperkalemia.

Today, we will discuss about hypokalemia. Before we talk further about causes of hyperkalemia and how do we manage this, we have to learn about basic physiology.



First fact to remember, potassium is mainly intracellular, the concentration of K is about 150mmol/L of H2O inside the cell as compared to about 5 mmol/L outside the cell ( in plasma). Therefore, to maintain this concentration, our body depends greatly on Na-K ATPase channel ( this channel transport 3 Na out of the cell for each 2 K it transports in), however , you must always remember there are H-K ATPASE in specific organs such as kidneys for similar purpose.

Potassium is mainly excreted in kidney although a small proportion is excreted through GIT.

OK, let us talk about causes of hyperkalemia, I can divide them into either increased load, reduced excretion and increased release from cells ( Remember? Potassium is mainly intracellular!)

1) Reduced excretion
Chronic kidney disease ( Potassium is mainly excreted via kidney )
Mineralcorticoid deficiency ( learn the effect of mineralcortiocid on Na-K channel, you will understand)
Some drugs ( especially ACEI/ARB, heparin, potassium sparing drug)

2) Increased load
Overzealous Potassium supplement
Transfusion of blood

3) Increased release from cell
Any causes leading to major cell breakdown such as tumour lysis sundrome, tissue necrosis, rhabdomyolysis
Acidosis ( Remember I told you about H-K pump!!)
Beta blocker

OK, I will talk about management of hyperkalemia in my next post.