help! clinical chemistry question

[fantasty]

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Ok, I'm not a pathologist or even a lab type person. But, I'm doing a small pilot study where we're trying to develop a new biomarker. We're going to be sending samples to a lab that normally doesn't handle biologic specimens. I know that I want to have them measure the serum, but I was also interested in having them analyze the cellular componet. From what I understand (from "Clinical Diagnosis and Management by Laboratory Methods" on MDConsult), normallly serum is allow to clot, then centrifuged. If we separate the serum from the clot at that point, can both be stored for analysis? Can we just use a red-top tube? (I originally thought I was supposed to use a lavander-top because I thought it had to be anti-coag but I guess that doesn't make sense).

Of course, my mentors (epidemiologists and nutritionists) aren't well versed in sample processing, and the lab folks don't have time to answer my questions.

Any help would be great. I'm definitely out of my comfort zone in writing up this protocol.

 

[Brian Pavlovitz]

Ok, I'm not a pathologist or even a lab type person. But, I'm doing a small pilot study where we're trying to develop a new biomarker. We're going to be sending samples to a lab that normally doesn't handle biologic specimens. I know that I want to have them measure the serum, but I was also interested in having them analyze the cellular componet. From what I understand (from "Clinical Diagnosis and Management by Laboratory Methods" on MDConsult), normallly serum is allow to clot, then centrifuged. If we separate the serum from the clot at that point, can both be stored for analysis? Can we just use a red-top tube? (I originally thought I was supposed to use a lavander-top because I thought it had to be anti-coag but I guess that doesn't make sense).

Of course, my mentors (epidemiologists and nutritionists) aren't well versed in sample processing, and the lab folks don't have time to answer my questions.

Any help would be great. I'm definitely out of my comfort zone in writing up this protocol.

If you want to be able to analyze the red cell component in addition to the plasma, you'll want to use a lavender top tube. Otherwise, you'll have a huge RBC/WBC clot that really won't lend itself to useful testing (that I'm aware of, anyway).

Of course, this is splitting hairs, but if you do use a lavender top and separate the cells, the liquid portion will be "plasma" (rather than "serum") because the clotting factors are still there. 😉

However, there are other types of anticoagulant, and some may or may not interfere with what you're looking for in the plasma.

I'm not exactly sure about storage. I think plasma is probably fine if it's frozen at around -20C (depending on how long you need it). I'm not sure about the cells, though. They may need to be stored in test tubes with some added glycerin so they don't rupture.