Your ESR value tells you how quickly your red blood cells settle in an upright tube: after one hour the lab checks how much clear plasma has formed at the top, in millimetres per hour. The ESR, in full the erythrocyte sedimentation rate, is an indirect measure of inflammation: inflammation raises certain proteins in the blood, those proteins make the cells clump, and the red cells then fall faster. In women this value regularly reads high with no inflammation behind it. Two ordinary causes explain that, and both appear further down this page.
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Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.
Check your own valueThe speed at which your red blood cells settle is measured over exactly one hour, usually by the Westergren method: the tube stands upright, and your result is the clear column at the top, in millimetres per hour. The movement underneath is called stacking. Red blood cells normally repel each other slightly and stay separate, but certain proteins in the blood cancel that repulsion, and stacked cells fall faster.
Two proteins drive this: fibrinogen gets going within days and immunoglobulins build over weeks. Both belong to your response to inflammation and infection, and neither is the inflammation itself.
There is a second dial, and it is often forgotten. The number of red blood cells also determines how fast they settle: with fewer cells in the tube they meet each other less, so it goes quicker. That is how anaemia lifts this result with no inflammation at all.
The limits the laboratory prints on your result are upper limits: 20 mm/hour for women and 15 mm/hour for men. A widely used rule of thumb also accounts for age: for women the age plus ten, divided by two, and for men the age divided by two. Laboratories apply their own limits, so always read the numbers on your own result.
A raised ESR often tells a woman something other than inflammation, because there are two ordinary reasons this result can read high while nothing is wrong, and both are often missed.
The first is heavy menstrual bleeding. It depletes your iron stores, and in time your haemoglobin falls. With fewer red blood cells in the tube your ESR rises, with no inflammation anywhere, and the result then looks worrying while the real question is about your iron. The order matters: your ferritin falls first, well before your haemoglobin moves, so a normal haemoglobin does not rule out a depleted store, and a raised ESR can be the first visible consequence.
The second reason is pregnancy. The ESR rises during pregnancy along an ordinary, physiological route; that is no sign of illness, and anyone unaware of it takes fright at a number that is entirely normal for that stage.
Beyond that, this value is slow for everyone. It lags behind C-reactive protein (CRP) in both directions: fibrinogen has a half-life of about four days, and immunoglobulins persist much longer still. So a high ESR next to a normal CRP often means something has already passed. Lupus is the exception: there, CRP can stay normal during a flare while the ESR climbs.
This value never identifies a cause. Your symptoms, your other values and your doctor's judgement decide what it means.
This value is ordered for complaints that have been going on for a while: unexplained fever, joint pain that persists or stiffness that will not ease are the usual reasons.
For women there is an extra reason to read it in context. If you have heavy periods, have your haemoglobin and your ferritin measured alongside it, because without those two you cannot place a raised result properly. If you are pregnant, bear in mind that the value naturally sits higher, and in that case do not compare it against a limit meant for women who are not pregnant.
The draw matters too. The tube has to stand upright at room temperature and reach the lab within a few hours, because a tilted tube gives a reading that is too high. A recheck only makes sense after several weeks, because this value moves slowly.
A low ESR is almost always ordinary. No lower limit exists that would require you to act, and a reading of 2 or 3 mm/hour is perfectly good.
Even so, some situations make a low number meaningful. Anything that changes the number or shape of your red blood cells slows the settling: polycythaemia gives too many cells, sickle cell disease and spherocytosis give cells of a different shape, and a sharply raised white cell count has the same effect.
There is a warning attached that is worth remembering. In exactly those circumstances a tidy result can hide genuine inflammation, so the number reassures while something is in fact going on. That is why this value is never judged apart from your other results.
A raised result fits many different situations. Inflammation and infection raise it, and an autoimmune disease does the same. For women, two ordinary causes come first: anaemia from heavy menstrual bleeding lifts this value with no inflammation, and pregnancy raises it physiologically, so with nothing wrong. That is why your haemoglobin always belongs beside this result, because if your haemoglobin is low, that already explains part of the number.
A mildly raised result is rarely worrying, especially soon after an infection or during pregnancy. Above roughly 100 mm/hour is a different matter: a value like that you discuss with your doctor, because several explanations are possible, and working them out requires assessment.
Low ESR is normal and indicates no active inflammation.
Elevated ESR indicates inflammation. Consider further evaluation for the underlying cause.
You cannot lower this value directly, and that is not the goal. The ESR is a consequence, so the answer lies with the cause. With heavy periods that is often your iron: have your ferritin and your haemoglobin measured before you think about inflammation, because a replenished iron store takes the main non-inflammatory cause off the table. If you are pregnant, a higher value need not tell you anything; discuss it with your midwife or doctor rather than comparing it against an ordinary upper limit.
Beyond that, give it time, because after an infection this value only settles over weeks, even when you already feel fine. The ordinary things help in the long run: not smoking, sleeping well, staying active and a healthy weight all help against low-grade inflammation, but do not expect a quick change in this number from them.
If the result stays raised, or you have had symptoms for weeks, discuss it with your GP.
Yes, and it is one of the most missed explanations. Heavy bleeding depletes your iron stores and in time lowers your haemoglobin, and with fewer red blood cells in the tube they settle faster. Your result then rises with no inflammation present, so have your ferritin and haemoglobin measured before looking further.
Yes. The ESR rises during pregnancy along an ordinary physiological route, and it is no sign of illness. So during that period, do not compare your result against a limit meant for women who are not pregnant, and if in doubt, put it to your midwife or doctor.
Usually not. CRP responds within hours and settles within days, while the ESR rises over days and falls only over weeks. This combination therefore often fits something already past, such as an infection several weeks ago, and your doctor weighs that together with your symptoms.
Your result carries 20 mm/hour as the upper limit for women. A widely used rule of thumb accounts for age: your age plus ten, divided by two. At 60 that rule gives 35, and the fixed limit can then flag you as raised while the value is ordinary for your age.
Count on weeks. Fibrinogen has a half-life of about four days and immunoglobulins remain in your blood far longer, so the result stays high for a while after you already feel well. A recheck only makes sense after several weeks rather than after a few days.
At a value above roughly 100 mm/hour, and with any rise alongside symptoms that will not pass, such as a fever with no cause, stiffness in your shoulders and hips, or a headache you do not recognise. These are not diagnoses, but they are good reasons not to wait and see.
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Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
ESR (Erythrocyte Sedimentation Rate)
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