ESR? CRP? PV? ...What’s it all about?

ESR?  CRP? PV? ...What’s it all about?

It can be confusing can’t it? Where do we start trying to work out what these different blood results mean to us as patients? This is not a comprehensive analysis of each test but should give you some background as to the reason why the ESR, CRP and/or PV tests are done. Of course, in the overall assessment other blood markers may be equally important in assessing health such as WBC (white blood cell count), HB (haemaglobin), Neutrophils (gobble up the bugs so if you haven’t got any neutrophils you are not in a good place!) etc. but in this blog I have set out to discuss only the inflammatory markers.

ESR (Erythrocyte Sedimentation Rate), CRP (C-reactive protein) and PV (Plasma Viscosity) are all markers of inflammation.

The ESR is the rate at which red blood cells sediment in a period of 1 hour. To perform the test, anti-coagulated blood is placed in an upright tube and the rate at which the red blood cells fall is measured and reported in mm/h. When an inflammatory process is present, the high proportion of fibrinogen in the blood causes red blood cells to stick to each other and settle, thereby increasing the ESR level.

Generally, ESR does not change as rapidly as does CRP, either at the start of inflammation or as it goes away. Both tests are elevated in the presence of inflammation; however, CRP appears and then disappears sooner than changes in the ESR. However, because ESR is an easily performed test, many doctors still use it as a long term monitoring test to assess the amount of inflammation caused by RA.

The ESR is an easy, inexpensive, nonspecific test that has been used for many years to help monitor conditions associated with acute and chronic inflammation, including autoimmune diseases such as RA. ESR is said to be nonspecific because increased results do not tell the doctor exactly where the inflammation is in the body or what is causing it, and also because it can be affected by other conditions besides inflammation. Used on its own the ESR is not a reliable marker of active RA disease and the results must be used alongside the doctor's other clinical findings, the patient's health history, and results from other appropriate laboratory tests.

A rising ESR may mean an increase in inflammation and/or a poor response to a therapy; a decreasing ESR may mean a good response. Levels of ESR regarded as within normal range are between 1-7mm/hour. However, this increases with age and females tend to have a higher basal ESR anyway with menstruation and pregnancy sometimes causes temporary elevations.

C-reactive protein (CRP) is a protein found in the blood, the levels of which rise in response to inflammation. Measuring and charting CRP values can prove useful in determining disease progress and/or the effectiveness of treatments.

While the CRP test is not specific enough to diagnose a particular disease, it does serve as a general marker for inflammation in RA. It is ordered as a regular monitoring device and repeated to determine whether treatment is effective. This is particularly useful for inflammation problems since CRP levels drop as inflammation subsides and rise as inflammation increases. CRP levels can be elevated in the later stages of pregnancy as well as with use of birth control pills or hormone replacement therapy (i.e. oestrogen). Higher levels of CRP have also been observed in the obese. The ‘normal’ values for CRP are <6mg/L.

PV is technically a more challenging test, and not offered by many NHS laboratories which tend to go with either ESR or CRP. Plasma viscosity is used to monitor inflammation and treatment efficacy in the same way as the ESR/CRP and whilst it is regarded by some as a more superior test it doesn't seem to be considered any more reliable than the ESR because levels can be slow to change. It is however more sensitive and more specific than either ESR or CRP when monitoring the activity of RA. Smokers have slightly higher PV than non-smokers. Normal values at 37degrees are 1.05-1.30, High 1.3-1.6 (usually found in active RA), 1.47 and above synonymous with other conditions.

This is intended as general information only and not specific to any given person. My ESR is ‘acceptable’ when it’s between15-20mm/hr. Others may have a ‘normal’ reading that equates to ‘5’ or even ‘40’. We are all very different. It is important that blood results are not taken out of context but used with symptoms and a person’s well being to assess the overall picture. A ‘one off’ high or low blood result can be a rogue, don’t get yourself into a pickle if this happens, have the test repeated a few weeks later. Interestingly, I have had an ESR of 122 and a CRP of 1 at the same test … make of that what you will, the rest of us were very puzzled :)

Lyn x

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  • very interesting Lyn, have always found that my ESR seems to take a long while to go up, I get lots of signs of a flare but ESR can remain low which is usually around 10-20 when I am doing well. Suddenly though it will shoot up high which by then I have already realised a flare is upon me.

    This was the case for me in the very early years so they tend to listen to me more as of course they know me very well, just as I know my RA.

    Does the CRP rise when infection is present or is that something different?

    mand xx

  • Hi Mand

    Yes, CRP will rise with infection as well as inflammation. So if you have a high CRP and little in the way of swelling the result would be indicative of infection ... somewhere, although it might be obvious such as chest or throat!

    Lyn x

  • This is brilliant. Now all I have to do is ask what my CRP and ESR reading are because I have never been told. All I know is my PV was high??!!

  • Julie...you've never been told?

    On MTX I was told to get my blood tested monthly and given a record card, every time I go to the hospital they write the latest results in it for me so I can see them and show them to anyone else who may have to treat me.

    Maybe youa re not on MTX

    Sue x

  • Hi Julie

    You would have to be different to the rest of the UK!! Have updated the blog to include PV (thought they only used that in Scotland!). As they have checked your PV levels they are unlikely to have done either ESR or CRP. I have just found the 'normal values' so will add those in now :)

    Lyn x

  • Lynn.

    Firstly thanks for all the info. you have given me over the past two years, especially about neutrophils. Secondly I am in the South of England and have always had PV and CRP tested for but never ESR. The lab. my bloods go to has over 1.72 as being high for PV, but I know that different labs. can have different boundaries, just don't want people getting worried if their results are higher than they expected.

    Thanks again for all your help and have the knee op.!

    Jenniet.

  • Hi Lyn.

    Beginning to doubt myself so did a bit of research. You're quite right with the boundaries for PV at 37 degrees. However most labs give the boundaries from 1.5 to 1.72. Just after being diagnosed mine was 1.92 and I knew it! However since the medication has kicked in I am normally in the high sixties so perfectly normal, although others might not say so!

    Jenniet.

  • Me? Different? ahem, I wonder if my blood is blue??

    My PV was 1.76

    Seriously though this is such useful information and I have learnt more from you than any nurse or doctor? Thanks Lyn x

  • 1.76 equals bad pain. inflammtion.. certainly in my case and surely yours unless you arean iron lady !!

  • Lynn,

    Fantastic & informative and very well written piece. I will be keeping this for reference.

    Do you write professionally? If not you should! I wish I had all this clearly explained in the beginning! Well done you! x

  • Hi Gina, did you have a good holiday? Hope your feeling better for it as you weren't to good before you went away.

    mand xx

  • my reading is never less than 1.58 and is usually 1.7+ so my das score which they have never measure is???!!!!!!, do the people treating know what the tests mean.. the lowest was 1.47 once.. obvioulsy have never achieved remission. words fail me,, seeing dr gp monday.. time for change of consultant and hospital,, last metho reading before coming off. dose had been ramped up was 1.78!!!

  • when mine rises above 1.71 im in a bad way.. 1.6 and under bad.. 1,5 and ok pain tolerable.. aaagg.. definately non smoker.. can advise on giving up if any one needs help as i have done my smoking cessation course as part of my training whilst i worked in retail pharmacy alison

  • thank you very much LYNW,it's so interesting good lesson.

  • Yes thanks Lynn for the info at Bolton NHS, they give you a monitoring card so everytime I have my bloods done either there or at GP's it goes on the little chart.

    At my worst I was ESR of 280+ and a CRP of 90+

    Since mthx and pred over the past year and a half after 25mg methotrexatre a week and normally 20mg of pred a day (but in a bad flare up to 80mg) Ive managed to get it down to around 80-90 ESR and 35-40 CRP but now got big hopes then Enbrel will get these down even further.

    Right its almost 3am now I need to try again to sleep through this pain here goes,,,,,,,

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