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Base excess

Blood gases · also printed as BE, Base excess (blood), cBase, ABE, SBE

Typical UK adult range-2 to 2 mmol/L

Ranges vary between laboratories; the range printed on the report takes precedence.

What this test measures

Base excess is a calculated number that summarises the non-breathing part of acid balance. Zero is neutral; negative values mean an acid load, positive values an alkaline one.

Why doctors request it

Part of every blood gas, used to gauge how severe an acid disturbance is.

What commonly pushes it up

Vomiting
Some water tablets as a class
Compensation for long-term carbon dioxide retention

What commonly pushes it down

Poor circulation and severe infection
Kidney failure
Diabetic ketoacidosis
Diarrhoea

Everyday reasons for a value outside the range

Small negative values are common after exercise or in dehydration

About the sample

Read with pH, pCO2 and lactate.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.

Got a report with Base excess on it?

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This is an educational summary of results you uploaded. It is not medical advice, a diagnosis or a treatment plan, and it does not replace the doctor who requested the test. If you are worried, or a result is marked outside range, discuss it with your doctor. Written and reviewed by a UK consultant physician. Reference ranges vary between laboratories.