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This is an issue which has been touched on, but never really been resolved. I am sorry to say that I have not been able to get a complete, satisfying answer either.
However, based on past discrepancies between the lab tests (SED Laboratories) and my home kit (UaSure kit=Artic Medical) of 1.5 -2 mg/dl Gave me some thing to think about. My doctor's answer was that that lba was more accurate than my kit. There may be a small difference between the accuracy, however, the consistent results of the labs and my kit lead me to believe that there are other factors involved.
?I think, I have isolated ONE ?factor: TEMPERATURE. My blood is ?about 85-90 degrees when I take the reading. Checking with the Labs, I was assured that the blood sample are refrigerated before the tests. So, at best, the tests are performed at ambient/room temperatures and the blood is around 70 degrees. After reading about the solubility of MSU (mono sodium urate) at 90 and at 70 degrees and the difference being about 2 mg/dl less at the lower temp, I believe that a similar relationship exists also for uric acid.
I proved my point by reducing my body blood temp in my middle finger and thumb by using a cold pack until the skin temp read about 68*, I placed the test strip on a cold pack some time to bring it in line and ran the tests. Here are the results (on Uloric 40 mg since 7/8/10):
?My kit ? ?(blood ~85*) ? ?SED Lab (blood~70*)
7/1/10 ? ?? 6.5 mg/dl? ? ? ? ? ? ? ? ? ? ? ?5.5 mg/dl
9/15/10 ?? 7.5 ? ? ” ? ? ? ? ? ? ? ? ? ? ? ? ?5.8 ? ? ?”
10/25/10 ?6.7 ? ? ” ? ? ? ? ? ? ? ? ? ? ? ? ?4.9 ? ? ?”
11/22/10? 7.0 ? ? ” ? ? ? ? ? ? ? ? ? ? ? ? ?5.2 ? ? ?”
12/4/10 ? ?5.7 ? ? ” ? ? (blood~70*)? 4.8? ? ? ?” ?(kit, not lab)
12/11/10? 5.7 ? ? ” ? ?Added this PM,As of tomorrow, I'll be on Uloric 80 mg.
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What I am saying is: The results from the labs seem to say that the uric acid is lower than the readings from the kit, meaning everything is honky dory. If the figures are in the lower ranges (3-5) then we need not worry, however, if the readings are in the 6-8 range we better take notice. The lower lab reading may be misleading and a gout attack/flare may be in the making.
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Any thoughts or additions on this subject??
Very interesting experiment Hans and yet another example of how gouties are often ahead of the game in understanding the discrepancies which exist in current medical practice. Unfortunately, it's probably only interesting to us.
My guess is that Drs are not terribly concerned about results that vary between less than 2mg/dl. Also, when you consider the normal fluctuation of SUA in the course of a day due to various factors: diet, exercise, hydration etc., they no doubt realise that a lab test is only a ballpark or snapshot figure. They probably conclude that as long as it's not off the scale and the process of urate lowering therapy is underway, everything will settle down in the end.
hans,
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I wish I could shed some light on the subject but my limited research has shown there are so many different ways to test for uric acid/urate that it is dizzy-making. I know it must be frustating to consistently get a point lower with your tester than at the lab. That's a reason why I never bought a tester…simple is not always best and it would bedevil me to have two different readings on which to base my decision making.
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There are so many variables but I think I can reasonably be sure that one that the labs have considered is the effect of temperature. It should not matter whether urate has precipitated or not, it is probably all dissolved in some reagent before the actual test.
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One thing I DID stumble upon, it seems that Vitamin C intake may interefere with the accuracy of some COLORIMETRIC methodology, and I am assuming that most home kits are reading color change of a reagent?that's the way they usually work.
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I think the upping to 80 mg. Uloric is a terrific idea to get both tests always below 5.0.
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How are the foot and the finger doing?
zip2play said:
hans,
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…it must be frustating to consistently get a point lower with your tester than at the lab. …
How are the foot and the finger doing?
Zip, it's the other way: I get higher readings with my kit and they are pretty consistent. I do trust my kit as much as I trust the lab readings. Once I figured out how much blood I need for the test I haven't had any problem getting decent readings.
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My foot and finger are doing fine. Both still have plenty of tophy left, but are not painful or disabling. I am hoping (banking) on getting rid of them with the Uloric 80.
Things are going so good that I was able to go sailing again yesterday. A first for me: My first sail as an “eighty”.?
odo said:
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My guess is that Drs are not terribly concerned about results that vary between less than 2mg/dl. Also, when you consider the normal fluctuation of SUA in the course of a day due to various factors: diet, exercise, hydration etc., …
Due to the fluctuations you mentioned, I have been taking my home tests generally at about the same time and under similar conditions to minimize those affects.
I am sure you are right regarding Dr's take on the subject.
Anyone know what happens when the sample cools on way to lab?
Do crystals precipitate and reduce the UA in solution thus reducing the reading gained?
I agree with the consensus that it's not absolutely critical what a level is -when looking at attack levels and treatment effect- but there are already too many variables in gout, to start with.
I can see that this topic is even more hard to nail than the usual suspect -of when to sample and what to make of the result, by many health carers.
trev said:
1) Anyone know what happens when the sample cools on way to lab?
2) Do crystals precipitate and reduce the UA in solution thus reducing the reading gained?
3) I agree with the consensus that it's not absolutely critical what a level is -when looking at attack levels and treatment effect- but there are already too many variables in gout, to start with.
4) I can see that this topic is even more hard to nail than the usual suspect -of when to sample and what to make of the result, by many health carers.
Trev:
1) I don't Think that any one really knows. One thing for sure, SED labs refrigerate their samples before tests. Other than that a lot of things may/can happen and the average layman would not get any info from the labs or doctors what's being done.
2)?That's a big mystery. UA in the blood is a solid (tiny crystals.) One cannot really say that the UA is dissolved in the blood. Second, to my knowledge, UA only precipitates as a MSU (mono sodium urate salt) We are not dealing here with a simple chemical process where an acid or salt (when added to water) split into positive and negative particles. We are dealing with blood as the solvent=carrier. I don't believe that we have any different electrical particles in blood. The different UA figures in blood at different temperatures is to me a complete mystery Why the figures are higher for higher temps doesn't make sense to me. ?Yeah, if some of that UA would have precipitated and it could be filtered out I could see a difference in UA concentration. But I don' t think that ?that is really happening; ?Some light could be thrown on it by having a lab test the same blood sample at various temps.
3) But Trev, I venture to say that the level is critical. If the “true” figure was 7.2 and the “not-so-true” figure 5.2 the the whole rigmarole would/could become critical because too much UA is in the system ?(in reality if 7.2 is TRUE.) Attack/flare could be imminent, chances for tophi to form are increased, kidneys may have to work harder to get rid of the UA/MSU and who knows what else.
4)?You are definitely right with your assessment. And, honestly, I don't know if I am spinning my wheels or not.
My bad- for sloppy posting, Hans-
On point 3, what I meant to convey was -It's more important to get sequential readings, and tally these with treatment and further? periodic measurements, rather than worry overmuch about 'absolute' values.
Especially, if not principally, due to this very point in discussion. ie:?what is good/bad in each sample?instance?
They're potentially unreliable on current suggestions.
This would explain the lack of focus in tallying?absolute SUA levels to symptoms -which seems to engender a sort of helplessness in approaching the scourge of gout in?a real?scientific sense!
No doubt, there's 'a lot of it about' ?
[PS:? I heartily support the plea for more research into this 'post sample drift' question of accuracy.]
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