Methaemoglobin
What this test measures
Methaemoglobin is haemoglobin whose iron has been altered so that it cannot carry oxygen. Small amounts are normal; more usually comes from certain medicines or chemicals.
Why doctors request it
Measured on a blood gas when oxygen readings from a finger probe do not match how someone looks.
What commonly pushes it up
- Some local anaesthetics, antibiotics and other medicines as a class
- Some chemicals and nitrites
- Rare inherited conditions
What commonly pushes it down
- There is no meaningful low value
Everyday reasons for a value outside the range
- Values just above the range are common and usually harmless
About the sample
Analysed promptly.
Upload a photo or PDF and see every line against the range your lab printed, explained in plain English. First report free.
Read my report freeThis 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.