Every time your lab results come back, there is a little number sitting quietly on that sheet — potassium. Most people outside the kidney world have never given it a second thought. But for those of us living with kidney disease, that number can mean the difference between a good day and a medical emergency.
Today on Lab Detective, we are diving deep into potassium — what it is, what it does, why your kidneys have everything to do with it, and what happens when it goes wrong.
What Exactly Is Potassium?
Potassium is a mineral and an electrolyte. Your body needs it to function. It helps your muscles contract, keeps your heart beating in a normal rhythm, supports your nerve function, and helps move nutrients into your cells and waste products out.
The normal potassium range in the blood is 3.5 to 5.0 mmol/L. Most healthy people maintain this balance without even thinking about it. Their kidneys quietly filter out any excess potassium through their urine, and life goes on.
But here is the thing — when your kidneys are damaged or failing, they can no longer do that filtering job properly. Potassium starts to build up in your blood, and that is where things can get dangerous.
Why Kidney Patients Must Pay Close Attention
Healthy kidneys filter about 90% of the potassium you consume through food and drink. When kidney function drops — especially below 30% (Stage 4 or 5 CKD) — or when you are on dialysis, your kidneys can no longer keep up.
Dialysis does remove some potassium, but only during your session. Between sessions — those long hours in between — potassium keeps building. This is why what you eat between dialysis days matters so much.
High Potassium (Hyperkalemia) — The Silent Danger
High potassium is called hyperkalemia. It is one of the most serious complications for kidney patients, and the frightening part is that many people feel absolutely nothing until it becomes critical.
Symptoms of high potassium include:
• Muscle weakness or heaviness in the legs
• Fatigue and general tiredness
• Numbness or tingling
• Nausea
• Irregular heartbeat (palpitations)
• In severe cases — cardiac arrest
Yes. Your heart can stop if potassium gets too high. This is not said to frighten you, but to help you understand why your doctors watch this number so closely.
Low Potassium (Hypokalemia) — The Other Side
Low potassium, called hypokalemia, can also happen — especially if you are restricting too aggressively, vomiting frequently, or on certain medications. Symptoms include muscle cramps, weakness, constipation, and abnormal heart rhythms. Less common in dialysis patients, but still worth knowing.
What Does Your Potassium Number Actually Mean?
Below 3.5 mmol/L — Low potassium (hypokalemia). Your doctor may adjust medications or diet.
3.5 – 5.0 mmol/L — Normal range. Well done!
5.1 – 6.0 mmol/L — Mildly high. Watch your diet carefully.
Above 6.0 mmol/L — Dangerously high. Medical attention needed urgently.
Foods High in Potassium to Be Mindful Of
• Bananas, oranges, avocados
• Tomatoes and tomato-based sauces
• Potatoes (especially boiled with the skin)
• Beans and lentils
• Groundnuts (peanuts)
• Plantain
• Coconut water
• Dark leafy vegetables in large amounts
A Word on Local Ghanaian Foods
Living in Ghana, some of our everyday staples are naturally high in potassium. Plantain, garden eggs, beans, and tomato stew are part of our culture and our identity. This does not mean you can never eat them — it means you need to be smart about portion size and preparation.
Leaching vegetables — cutting, soaking, and boiling — can help reduce potassium content significantly. We will cover this in much more detail during our diet month coming up.
My Personal Experience With Potassium
I have been through dialysis, a kidney transplant, and I am back on dialysis. Over 15 years, I have seen my potassium creep up after enjoying a meal I thought was completely safe. I have felt that strange heaviness in my legs and wondered why — only for my labs to confirm a high number.
It taught me that this is not about perfection. It is about awareness.
You do not have to be afraid of food. You just have to be informed. And that is exactly what Lab Detective is here for — every single Wednesday.
Next Wednesday we decode another important lab value. Until then — eat wisely, live fully. 💙
