Definition
What Potassium measures
Potassium is the main electrolyte inside cells, with only a small, tightly regulated amount in blood. Nerves, muscles, and especially heart rhythm depend on that narrow blood range.
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Kidney & electrolytesCompletemmol/L
Potassium
The heart-rhythm electrolyte inside cells
Illustrative sample band · Synthetic
4.3mmol/L
3.4Sample target 3.8–4.8 mmol/L5.3
Why it matters
How clinicians usually read it
It is one of the few routine markers where meaningful deviation in either direction matters quickly, and several common medications move it.
When it reads low
A lower value can mean
A low potassium can follow vomiting, diarrhea, some diuretics, or low intake. Symptoms include cramps and weakness; significant lows need correction under clinical guidance.
When it reads high
A higher value can mean
A high potassium can be real — kidney clearance or medication related — or an artifact from red cells breaking during collection. Unexpected highs are usually confirmed with a repeat draw.
Questions for a clinician
Bring the number into a real conversation
01
Could this be a collection artifact, and should we redraw to confirm?
02
Do any of my medications or supplements move potassium?
03
What symptoms should prompt urgent attention with a value like this?
Educational boundary
Educational information only. Displayed ranges are illustrative sample bands, not a diagnosis, treatment plan, or substitute for the contracted laboratory report and a qualified clinician.
See it as a sample result
The sample dashboard shows an illustrative reading, target band, and trend for Potassium.