Lipid profile

[wyldkhatdd]

Hi, So I'm doing a standard operating procedure for Lipid Profile. U know Total cholesterol, Triglycerides, HDL, LDL and VLDL, what is the principle behind the routine laboratory procedure?

Eg, Polipol precipitating reagent for HDL

[theprof]

Polipol Precipitating Reagant is used for separation of HDL from other serum lipoproteins. It interacts with LDL and VLDL at a pH of 10 and greater, forming insoluble complexes. .

The precipitate of complexes is removed by centrifugation and the supernatant is analyzed for HDL cholesterol.

One important factor is that the reaction occurs at room temperature unlike some of the older tests. Storage of this reagant can sometimes be problematical and I'm told it has a relatively short shelf-life.All the same, it is an improvent on the older Liebermann-Burchard cholesterol reagents and others which contained divalent metal ions and are not so sensitive.

I hope that answered the question. If not, get back to me and I'll try again although I'm a bit rusty on this subject as I don't spend that much time these days in the hospital laboratories.

[bagofslugs]

Gee Prof, why not just post a link to the source you lifted your answer wholesale from, so wyldkhatdd can see it in full for himself.

Never mind, I'll do it for you
http://www.cimascientific.com/2510.htm

Who needs a hospital laboratory when you've got the internet!

[theprof]

I didn't lift the answer my friend.

I've had a look at the website and it contains information that I did not post so how can it be "wholesale lifting". Why would I not have posted more of it to appear to be a better authority?

I've also stated that Polipol reacts at a pH of 10 and above. Can you find the "above" bit on the website. I can't.

And while I'm about it, I am a university biochemistry professor and I do spend time in hospital laboratories, although not sometimes as much as I'd like to. Polipol is something I've got "hands-on" experience of.

I do appreciate that your new to the Answebank, but you need to realise that there are people out here that use this stuff

[bagofslugs]

Well you got me, the simple addition of the word 'above' means that none of your answer came from there, how foolish of me.

Enjoy the link, maybe you'll learn something new from it as well! Spread the knowledge, that's what I say!

[theprof]

Well, that's how it is my friend. At the end of the day, it's your choice.

Unfortunately, it wouldn't be possible to learn something new from the website. You need to appreciate that the data sheets issued by the supplier to laboratories contain more information than is on the website you cited. This is not unusual and users are expected to absorb much of this information prior to use. It does tend to stick in the mind.

Pity my memory isn't better or I could have provided more detail in my original post to enable you to be absolutely positive I lifted the answer wholesale. Bit of a mystery why I didn't isn't it?

You see, no matter which way you want to look at it, the questioner was asking about a well-known laboratory procedure that thousands of lab technicians and scientists could write about in their sleep. To you, it may seem complicated and demanding considerable expertise and knowledge to answer. To people who perform this procedure, they could do it in their sleep and explain it. I've also used Polipol it but as I tried to imply earlier, it was some time ago - I've got lab technicians to do this type of work nowadays.

Tell you what. Let's wait and see if wyldkhatdd is happy with my reply and go from there.

[wyldkhatdd]

Dont mean to choose sides here but I found that web site also, so I didnt really need it thanks though bagof slugs, I apreciate the effort. Prof did help i was kinda looking for a lil history on the tests like Prof told me, so ty Prof. On that note I dug somemore and found that the cholesterol methods have been around since the late 1800 which is a surprise since lab tech is fairly new.
Cool bio chem lecturer, I actually enjoyed that course.

[wyldkhatdd]

BTW I just remebered a ques, what is the relationship between VLDL and Triglycerides? The lineality has something to do with 400mg/dl right?

[wyldkhatdd]

Linearity*********

[theprof]

That's correct - the 400mg/dl figure is of crucial importance.

As you know, cholesterol and triglycerides are insoluble and are transported between the intestine, liver and periphery in the form of soluble compounds called lipoproteins. These lipoproteins are classified into chylomicrons, vldl's, idl's, ldl's and hdl's.

The vldl's are synthesised mainly in the liver and represent endogenous triglyceride synthesis using ffa's and glycerol. The ffa�s may be synthesised De novo (N.B biochemistry meaning not literal latin meaning) or by oxidation if sufficient dietary fat is available.

All the lipoprotein particles contain varying amounts of triglyceride, protein and cholesterol. However, each particle has a known, relatively constant, amount of triglycerides, protein and cholesterol unique for that species. Furthermore, vldl's are the largest carriers of triglycerides.

Because of these factors, it is possible to provide a rough estimation of the vldl cholesterol by dividing the measurable triglyceride value, expressed as mg/dl, by five. No direct, automated method of measuring vldl cholesterol has ever been devised, although it can be done in specialised research laboratories.

A further refinement of this method is the so-called Friedwals Equation. This is used to estimate ldl from total triglycerides, hdl and cholesterol:

ldl= (total cholesterol - hdl cholesterol) - (triglycerides/5)

This equation provides a fairly accurate picture of ldl and is indeed linear until we reach the 400mg/dl limit. When the triglycerides present exceed 400mg/dl, very odd figures can result. The calculated figures have been known to be above and below the true figures when analysing the same batch in these circumstances. Consequently, it is not possible to linearly extrapolate the likely error.

[theprof]

Incidentally, where are you studying in the caribbean and what course are studying?

[theprof]

I'll try again:

Incidentally, where are you studying in the caribbean and what course are you studying?

That's better.

[wyldkhatdd]

I'm doing My Medical Laboratory Technology Degree In Trinidad. I'm in my second yr. I did Bio chem last semester, and got a b+ and I'm doing Clinical Chemistry and Histology this semester.

I had to give up some SOPs on a lipid profile. I gave them up today I put alot of work into them. I hope i get a good mark.

[theprof]

Thanks for the info. I always find it useful to know about the course(s) being undertaken as I don�t need to discuss stuff you that you already know or ramble on about advanced stuff your never likely to encounter.

Sop�s need a lot of careful thought and discipline to get them right but they�re always worthwhile. They�ve saved many potential disasters over the years with us.

Good luck with your degree. My senior research assistant is a former graduate MLSO and she�s got outstanding practical knowledge of lab procedures - I'd be lost without her. ( I'm not just saying that because she's sitting beside me!)