Well, what we do in our clinical lab is pretty much as you describe. We
collect the blood in serum separator tubes (SST) and centrifuge to
separate the serum. The SST allow us to test without pouring off the
serum. Then we place it in our $75,000 analyzer and print out the
results.

Of course that can only be accurate if the proper maintenance is
performed, the instrument is properly quality controlled with know
controls, calibrated to the exact specifications. We also run unknown
samples from the College of American Pathology to prove that we are
accurate. We also run patient samples on duplicate instruments to prove
that there is little instrument to instrument variation.

But I'm thinking that you are probably looking for a much simpler
instrument like a spectrophotometer. Then you should know that the
instrument read out will only be a meaningless number that compares
your sample to a blank and then you have to chart the reactions to
compare your test value with the known values. However I know that
there are moves to make more POCT tests available and there may be
something out there for this - as long as you adhere to a strict
protocol of QC, calibrations and maintenance.

Your best bet would be to have your doc write an order for you to
receive the Mg levels from the lab directly. If the lab that draws the
blood and runs it at the same place should be able to give it to you
within a couple of hours.

Are you going to the lab to have your blood drawn, or are you having it
drawn at your doc's office? In the latter case, they have to spine down the
blood (hopefully in the office),  package up the specimen, have the courier
pick it up and take it to the lab, and then have the lab do the test. If
you're in an extremely rural area, this can take a lot of time.

Find out where the lab is and go to their on-site drawing station, if
possible. If it's a hospital lab, go right to the hospital and have your
blood drawn there. Make SURE you have something from your doctor saying they
can release the results directly to you. If you can provide them with a fax
number so much the better, as they can fax you the results directly. They
can place a "fax to" in the original order (our lab does this every day) and
they can fax the results, upon release, directly to you and/or your doc's
office. Of course, someone at the office has to pull stuff off of the fax
machine regularly, then DO something with the results. That is probably
where your problem is. If the lab give you a hassle about getting your own
results, make sure you speak with the head of chemistry/lab manager, or
their client service department (depending on how large the place is).
Again, the lab cannot release to you on your say-so only; doc must approve
of this arrangement in writing. It's all about liability here.

There is a handheld instrument called the I-Stat that they use in many ER's.
I found one page that had their test menu, but magnesium was not one of the
capabilities. I didn't have time to search further. If anyone knows if
I-Stat can perform Magnesium testing, please post here :-).

I find it difficult to believe that it takes 2-3 weeks to obtain a result.
This testing is done same day, unless your lab is so incredibly tiny that
they're sending it out because you live in some extremely remote area or
something. Your doctor's office must be dropping the ball as far as getting
results back to you. They should be getting the results next day in most
cases IF your magnesium is done on-site at your laboratory. Again, if your
specimen is traveling to a large reference lab via the doc's office and a
small intermediary lab, this can take time, but 2-3 weeks is ridiculous. No
reference lab could take that long to do a magnesium - they'd be out of
business!!! [I used to be a reference lab marketing rep twenty years ago.]

Sit down with your doc or a representative person at his/her office and
explain the problem. Ask how you can expedite this. You can get a standing
order written for your local laboratory that will last a year, so you can go
into the lab [draw station] whenever you need to (or however often the order
specifies) and get your blood drawn. Home magnesium testing is probably  not
the way to go, as it's pretty complicated.

Hope this helps.

Judy Dilworth, M.T. (ASCP)
Microbiology (but used to do chemistry and lab marketing)

As such, I was looking into the possibility of getting some lab

I have heard this SO many times - the doctors make out that the patient has
got some absolutely amazingly rare condition and also pretend that the lab
is SO hopelessly inefficient so patients come to think that every lab test
takes weeks.

The fact of the matter is that the vast majority of tests are done and
reported the same day, often within a couple of hours - serum magnesium
levels certainly are.
The cause for delay is that the doctor doesn't have a free appointment for
the patient for several weeks, but rather than admitting it, the onus is
passed on to some faceless laboratory.
As for sending you the results directly, where we are in the UK, that's
standard practice, but patients can phone for results.

The easiest way is to get an used spectrophotometer and the manual  
procedure for a magnesium assay.  Serum magnesium is a relatively easy  
manual test.  You will need some additional supplies in order to make  
reliable standards and you will need a source of deionized water.  If you  
are still interested I can get you a copy of a procedure and a list of the  
reagents you will need to do the manual procedure.  You might be able to  
find an older model Coleman spectrophotometer through a used medical  
supply company.  (arciemizelle@frontiernet.net)