Discussion in 'BioMedical ME/CFS Research' started by Andy, Jun 10, 2019.
Open access, https://www.sciencedirect.com/science/article/pii/S0889159119302089?via=ihub
What's the difference between CRP and hsCRP? My CRP has always been normal.
I can only find one result for myself, from 2016, and CRP was normal for me too - less than 1. I had been ill for 21 years.
hsCRP is high-sensitivity C-Reactive Protein.
I've never understood the purpose of the hsCRP test. Think about the situations that could arise :
1) Someone has hsCRP and CRP tested. The results are very similar. What has anyone learned? Nothing.
2) Someone has hsCRP and CRP tested. The results are significantly different. What has anyone learned? One of these tests was conducted poorly, but nobody knows which one.
hsCRP and CRP are testing the same thing, as far as I know, but one uses a testing method deemed to be more accurate.
For some reason I don't understand the hsCRP is considered more useful for testing inflammation affecting the heart. CRP is considered more useful for testing inflammation of other organs or parts of the body.
See this link :
and this question on that page :
What is the difference between regular CRP and hs-CRP tests?
Answer : Both tests measure the same molecule in the blood. The hs-CRP is for seemingly healthy people who may be at risk for heart problems. The CRP test is requested for patients with inflammation, who may need to be monitored for conditions such as rheumatoid arthritis.
I think the people who make hs-CRP tests have discovered a nice little earner.
Edit : grammar
I forgot to say...
At my own expense, and to satisfy my own curiosity, I had hs-CRP and CRP tested from the same blood sample once. CRP was 1.4 and hs-CRP was 1.38. Apart from satisfying my own curiosity, what did I learn? Nothing.
hsCRP is measured in research about chronic low grade inflammatory disease. It's studied as a risk factor for heart disease. There is a lot of consensus now that heart disease start with chronic low grade inflammation.
There are people who think ME/cfs is also a chronic low grade inflammatory disease. Good that they did this study! My hsCRP has always been high.
But that doesn't really explain the difference between hs-CRP and CRP. Both tests measure the same thing, so hs-CRP results will always be very similar to CRP results. I'd like to see an explanation of what the significance of the tests is if they are significantly different, given that they are measuring the same molecule in blood. It just says to me that if a significant difference is detected then one of the tests was conducted poorly.
hsCRP is, as others have said, just a highly sensitive assay for CRP. It is more sensitive rather than more accurate - i.e. it picks up differences below about 2. The standard CRP assay is not designed for that because CRP levels relevant to overt inflammation are in the range 5-200. Anything less than 3 is not useful evidence of significant inflammation.
Below the 3 level it seems likely that low grade inflammatory changes in things like coronary arteries can be picked up as higher means of populations but because CRP levels vary significantly between individuals with the same amount of inflammation you cannot tell anything about an individual person from an hsCRP result. So hsCRP is really only used routinely for research. Having said that, tracking hsCRP levels can be useful in people with e.g. RA who have a very low response profile - so instead of tracking their inflammation in the 5-50 range you track it in the 1-10 range. But as a one off hsCRP is largely pointless.
It is interesting to see a difference in this study. However, the median levels are not so very different and around 1 (normal). There is a wide range in the ME/CFS cases going up above 10, which almost certainly means at least one person in the group had some other inflammatory process going on.
I think the real message from this study is that it confirms that most people with ME/Cfs have normal CRP levels so CRP does not indicate significant inflammation in ME/CFS.
Sorry, I'm not sure what you mean. Are you saying that the differences between them can be seen if CRP and hs-CRP are both below 2? But surely with results that low they aren't considered significant for anything anyway?
No I am saying that hsCRP can distinguish levels of 0.2 from 0.4 from 1.2 etc. whereas the standard CRP test scale just stops at 1 or 2 and below that the readout is just <1 or <2. Read 'differences' as 'levels' in the bit you quoted from me.
So hsCRP is more sensitive meaning that it can pick up smaller amounts.
However that does not necessarily mean it is more accurate. It might give more rogue readings due to artefacts for all I know. So if an hsCRP test gives a level of 7 and the CRP test says 5 it may be that the CRP is more reliable there.
I think the high sensitive methode measured exact values under 5. The normal CRP just says <5.
My hsCRP is always around 5. When I was in remission it was 1. I don’t know if it is relevant. I have a lot of inflammatory markers that are off.
For example I had high calprotectine in my stool, but because they didn’t find crohn’s or CU, it wasn’t relevant?
Thank you for that explanation, @Jonathan Edwards
Just wondering - could our multitude of 'normal' results be related to low blood volume?
That is something I would love to know!
I have read that low blood volume is known to be an issue for people with hypothyroidism which is a condition that frequently gets mentioned in connection with ME, and I'm sure other conditions must be relevant as well. However, I don't know how blood volume is measured with any accuracy - it must surely be estimated, and I have no idea how good these estimates would be.
Doctors can't bleed the patient into a big jug and then say, "Ah, yes, Mrs X, you have five litres of blood which is average for an adult according to wikipedia. Jolly good show!" and then pour the blood back in to the patient. Wouldn't it be good if that was possible.
I can't see a reason that would fit that. CRP levels are dependent on production by liver and go up and down rapidly with production - up to 200 fold.
There is an accurate test for blood volume though it is not often used. It involves injecting a measured amount of a radioactive tracer, then withdrawing a measured amount of blood and calculating blood volume from the ratio of tracer found in the blood sample.
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