Hi pcventures,
I?ve done contract work for this lab, and am pleased to answer this
question for you. I will explain first why groups of tests have the
names they do, although you will see that all US clinical labs are now
standardized, then I?ll outline the tests for you.
Until about 5-6 years ago, each lab test could be ordered separately,
or as part of a panel or profile. Each hospital, or lab had their own
menu of tests. For example, Hospital A might call a panel that
included glucose, BUN, creatinine, sodium, potassium, chloride and CO2
a ?Chem 7? . Hospital B might have the same panel of tests, without
the CO2, but they call it ?Panel 1?. Because many doctors have
privileges in more than one hospital, and other medical staff change
jobs, this caused numerous ordering mistakes; duplicate testing, tests
not getting ordered and insurance compensation nightmares, lowering
the quality of patient care, and raising the price of testing.
What frequently happened was, a doctor would write an order for a Chem
panel, then separately order some of the individual analytes. The ward
clerk didn?t know any better, or was so used to following to the
letter what a doctor told her, would order duplicates. The lab would
run the panel, AND the individual tests. The insurance companies
finally caught on to all this duplicate testing and the resulting
duplicate charges, and jumped in with a scheme to standardize
everything. The standardization has its pros and cons. Even though
everything is standard today, many of us continue to use the old
terminology, compounding the mayhem.
Today, all US clinical labs have the same name for their tests, both
singly and in panels or profiles.
(In house names may vary, but patient ordering and results are all
standardized.) Medical personnel LOVE acronyms, and almost ALL lab
tests are acronyms.
The most common ?Standard workup? includes a hematological panel - a
CBC (Can be called ABC and stands for Complete Blood Count, or
Automated Blood Count) and a chemistry panel - a BMP (Basic Metabolic
Panel). If the doctor wants a little more, then a CMP would be ordered
in place of a BMP.
The CBC includes:
WBC (White blood count) Primarily used to indicate infection, leukemia
Normal is 5.0-10.0
RBC (Red blood count) Used to indicate anemia Normal is 4.5-6.0
Hgb (Hemoglobin) Used to indicate anemia Normal is 11.8-14.5
Hct (Hematocrit) Used to indicate anemia Normal is 35- 47
MCV (Mean cell volume) Measures the amount of hemoglobin a cell
can hold Normal 80-100
MCH (Mean corpuscular hemoglobin) Measures the amount of hemoglobin
the cell is holding Normal 27-31
RDW (Red cell distribution width) Measures shape /content ratio of
the red cells. Normal is 12-14
Platelet Count ?small cells needed for blood clotting Normal is 140-450 thousand
Automated differential ? The analyzer counts the ratio of different
white cell families
Manual differential ? The blood is looked at under the microscope by a technologist
** Note: Normal ranges can vary a bit from lab to lab due to different
techniques, reagents, temperatures, analyzers, etc. To determine if
your results are within normal limits, they must be compared to the
normal range supplied by the performing lab.
BMP: includes
Glucose - a screen for diabetes Normal 70-105
BUN - a screening for kidney function Normal 7-20
Creatinine - another screening for kidney function Normal 0.8 ? 1.4
Calcium ? high or low values can indicate many different disorders Normal 8.7-10.0
Sodium - The next four analytes are called collectively?electrolytes?
, measures acid-base imbalance, and indicate numerous disorders if not
in normal range. Normal is 135-143
Potassium Normal 3.7-5.0
Chloride Normal 97-105
CO2 Normal 20-29
For a ?standard workup? with a bit more, the doctor will order a CMP
instead of a BMP.
A CMP (Comprehensive Metabolic Panel) includes 14 tests:
A BMP plus:
TP (Total Protein)
Albumin (Another protein)
Liver enzymes: (Liver function tests)
ALT (Alanine aminotransferase) This used to be called SGPT, and many
doctors still call it that.
AST (Aspartate aminotransferase) This used to be called SGOT and many
doctors still call it that.
ALP (Alkaline phosphatase)
Total Bilirubin
If you got a cholesterol value, then your doctor must have done a
lipid panel as well. This includes
Cholesterol - a type of lipid(fat)
Triglycerides ? a type of blood lipid
HDL (High density lipoprotein ? ?good cholesterol?)
LDL (Low density lipoprotein)
VLDL (This is calculated from the measured values)
Cardiac Risk Factor (This is calculated from the measured values)
Now, once you have all these tests done, the results can tell your
doctor many things. Since I?m particularly fond of hematology, I?ll
start again with the CBC.
All of the CBC parameters are measured with using a very small amount
of blood, less than 1cc (A teaspoon is 5cc). The blood is sampled by
a very sophisticated analyzer, utilizing a laser beam, reagents, and a
computer. The analyzer has 2 chambers; one counts your white blood
cells, using electrical impedance. The other chamber counts the red
cells and platelets, using electrical impedance. The laser examines
the white cells for maturity, and the red cells and platelets for
shape and size. All the data is plotted on a computer screen into a
histogram, a nice colored chart showing the scatter of the cells.
If the analyzer shows anything out of the ordinary, the test is
repeated for accuracy. Then a smear is made. This is called a
differential. A small drop of blood is placed on a glass slide, and
the blood is pushed or pulled, depending on the technologist?s style,
very thin. This is dried and stained, enabling the technologist to
look at the ?diff? under the microscope. In this way, we can see
immature white cells that indicate diseases such as leukemia or
multiple myeloma, a decrease of platelets which is called
thromcocytopenia, and much more. We also look at the shape, size and
color of the red cells to determine various things such as anemia,
lead poisoning, and malaria, to name just a very few.
If you watched when your blood was drawn, you saw the phlebotomist
draw a purple topped tube, and either a red, green or gold topped
tube. The purple top has an anti-coagulant called EDTA which keeps
the blood from clotting in the tube. This tube is used for the
CBC/Hematology. It would be impossible to count cells if they were all
caught up in a coagulated clump! The red, green or gold topped tube
has no anti-coagulant in it. In fact, most tubes in use have an agent
that causes the blood in the tube to clot faster than usual. For
chemistry tests, blood is centrifuged (we say ?spun down?). This
causes the cells to fall to the bottom of the tube, leaving nice clear
serum or plasma, depending on which color stoppered tube is being
used. (Different labs use different samples, serum, plasma, etc.)
For the chemistry tests, the serum or plasma is sampled again, by a
different type of analyzer. Depending on the technology of each lab,
the serum is mixed with different reagents(chemicals) to enable each
analyte to be measured. It would take pages and pages to explain each
test?s chemical reaction here)
All the analyzers are interfaced with a laboratory information system
(LIS), into which all your results are entered and compiled, and
finally sent to your doctor with all the normal ranges,
Using these two sites, you can look up most lab tests, their values and meanings.
http://health.allrefer.com/health/test.html
http://www.labtestsonline.org/understanding/analytes/cmp/cmp.html
Whew! To give you a simple answer, the most commonly ordered ?Standard
workups? are:
1) CBC and BMP
2) CBC and BMP and UA (Urinalysis)
3) CBC and CMP
4) CBC and CMP and UA
5) CBC and CMP and Lipid Panel
6) CBC and BMP and Lipid Panel and UA
By ordering a CBC, CMP, lipid panel and a UA, the doctor can screen
for the following and more:
Anemia
Leukemia
Kidney function
Liver function
Urinary tract infection
Diabetes mellitus, and diabetes insipidus
Mononucleosis
Some thyroid disorders
Red cell diseases
White cell diseases
Platelet diseases
Some protein disorders
Some bone diseases
Potential heart arythmias
Potential heart disease
Electrolyte imbalance
If any analyte is outside normal range, further (and more expensive)
testing can be ordered for confirmation. The above tests are general
screening tests, and are a good tool for checking general health.
If any part of my answer is unclear, please request an Answer
Clarification before rating. This will enable to me to assist you
further, if possible.
Regards,
crabcakes-ga
Search Strategy:
Lab analyte values
Personal knowledge from working in the field |
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