Potassium (K)
Potassium is the primary electrolyte inside cells and is essential for maintaining normal heart rhythm, muscle contraction, and nerve signaling. Even small changes in blood potassium can have dramatic effects on the heart. The kidneys are the main regulators of potassium balance, which is why kidney disease often disrupts potassium levels.
Reference Ranges
Male
3.5 – 5
mEq/L
Female
3.5 – 5
mEq/L
Child
3.5 – 5.5
mEq/L
Ages 1–18
Reference ranges may vary by laboratory. Always compare with the range printed on your lab report.
What Low Levels Mean
Low potassium (hypokalemia) causes muscle weakness, cramps, fatigue, constipation, and dangerous heart rhythm abnormalities (arrhythmias). Common causes include diuretics, vomiting, diarrhea, excessive sweating, and low dietary intake. Below 2.5 mEq/L is a medical emergency.
What High Levels Mean
High potassium (hyperkalemia) can cause life-threatening cardiac arrhythmias. Symptoms include muscle weakness, numbness, and palpitations — but often there are no warning signs until the heart is affected. Causes include kidney disease, ACE inhibitors, potassium supplements, and tissue destruction (crush injury, burns).
Frequently Asked Questions
What foods are high in potassium?
Bananas, oranges, potatoes, spinach, tomatoes, coconut water, dal, and yogurt are rich in potassium. Most Indian diets provide adequate potassium. Patients with kidney disease may need to limit these foods to prevent dangerous potassium buildup.
Can a falsely high potassium result occur?
Yes — called pseudohyperkalemia. If the blood sample is hemolyzed (red cells burst during collection), potassium from inside cells leaks into the sample, giving a falsely high reading. Clenching the fist during blood draw can also raise potassium slightly. Always repeat an unexpectedly high result.
Why is potassium so important for the heart?
Potassium controls the electrical activity of heart muscle cells. Too little or too much disrupts the electrical signals that coordinate heartbeats, potentially causing arrhythmias — from benign palpitations to fatal ventricular fibrillation. This is why potassium is checked urgently in any cardiac emergency.
This information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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