JARGON BUSTER

Scientific terms decoded. This week: ESR (erythrocyte sedimentation rate) IF YOU’VE had blood tests for an infection, you probably had your erythrocyte sedimentation rate (ESR) checked — even if you didn’t realise.

This blood test measures inflammation levels. As well as infection, it can point to conditions, such as rheumatoid arthritis, and monitor them.

The test evaluates the rate at which red blood cells fall in a test tube. The word ‘erythrocyte’ means red blood cells and ‘sedimentation’ describes their movement.

In a patient with little inflammation, the cells fall slowly, leaving plasma (the straw-coloured liquid in blood) at the top. With higher levels of inflammation, cells fall faster.

This is because there are more proteins, which are generated as part of the body’s defence mechanism against infection.