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.
No comments:
Post a Comment