Potassium

Also written as: K

An electrolyte critical to heart and muscle function.

What it measures

The concentration of potassium in blood. It is tightly regulated because both high and low values affect heart rhythm and muscle function.

Why a doctor orders it

Included in metabolic panels and monitored closely with medications that affect it, including several blood pressure and heart medications and diuretics.

What is generally associated with a higher result

Broadly associated with reduced kidney function, several common medications, and with the sample itself - red cells breaking in the tube release potassium and produce a falsely high reading.

What is generally associated with a lower result

Broadly associated with diuretics, vomiting or diarrhea, and some hormonal conditions.

Everyday things that move this number

Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:

A difficult blood draw, which is a very common cause of a falsely high result
Clenching your fist repeatedly during the draw
Delay before the sample is processed

Questions to take to your appointment

Could this be a sample problem that needs a repeat draw?
Do any of my medications affect potassium?

Build a printable questionnaire with your own results →

Where to read more

MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .

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