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M-R >> S-Z |
| The 3X Rule |
Hemoglobin x 3 = Hematocrit (± 2%)
In normal blood samples, the hemoglobin is approximately one third the
hematocrit. This relationship can be used to cross check the accuracy of the
blood counts. If abnormal, the sample should be checked for hemolysis or
Heinze bodies. |
| Thyroxine
|
Thyroxine is a hormone synthesized in and
secreted by the thyroid gland. The primary secretory form of the thyroid
hormone is tetraiodothyronine (T4), although some triiodothyronine (T3) is
also secreted into the blood. The ratio of T4 to T3 is 25:1 in canine plasma.
Once in the blood, T4 and T3 are bound by transport proteins. The primary
binding protein is thyroxine-binding globulin (TBG) in the dog and albumin in
the cat. Upon delivery to the target cell, T4 is deiodinated to T3 at the cell
surface. T3 is the biologically active form of the thyroid hormone and more
readily enters the target cell. |
| Total Bilirubin
|
Bilirubin is an orange-yellow pigment found
in bile. It is formed when hemoglobin, the red-colored pigment of red blood
cells that carries oxygen to tissues, breaks down. Small amounts of bilirubin
are present in blood from damaged or old red cells that have died. In general,
bilirubin can be combined or conjugated to a protein called albumin, in which
case, conjugated bilirubin is often referred to as direct bilirubin. Bilirubin
that is not attached to the protein is called indirect bilirubin.
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| Total Cholesterol/HDL
ratio |
Cholesterol is a structural component in
cell membranes as well as in plasma lipoproteins. It is also used to form
steroid hormones, bile acid and glucocorticoids. Typically, the body
synthesizes most of the cholesterol the body needs. The cholesterol in our
diet can increase the levels in our body. Too much cholesterol, however, is
implicated in coronary artery diseases, which can lead to heart attacks. HDL
is one of the classes of lipoproteins that carry cholesterol in the blood. HDL
is considered to be beneficial because it removes excess cholesterol and
disposes of it. Hence HDL cholesterol is often termed "good" cholesterol. The
combination of total cholesterol and HDL ratio is used to determine the risk
of developing coronary artery disease.
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| Total Protein |
A total protein assay measures the amount of
proteins found in the plasma. The two major protein components are albumin and
globulins. Plasma proteins play a major role in maintaining colloid osmotic
pressure, and are a source of amino acids. They also bind and transport a
variety of substances including lipids, fatty acids, lipid-like substances,
copper, iron, and hemoglobin.
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| Triglycerides |
Triglyceride testing measures the amount of
triglycerides in your blood. Triglycerides are the body's storage form for
fat. Most triglycerides are found in adipose (fat) tissue. Some triglycerides
circulate in the blood to provide fuel for muscles to work. Extra
triglycerides are found in the blood after eating a meal when fat is being
sent from the gut to adipose tissue for storage. The test for triglycerides
should be done when you are fasting and no extra triglycerides from a recent
meal are present.
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| Urea Nitrogen (BUN)
|
Urea is one of three end products of
nitrogen metabolism. Blood levels of urea are typically low and relatively
constant since the primary mode of urea excretion is through the kidneys. The
action of antidiuretic hormone on the permeability of the medullary collecting
duct allows urea to diffuse into the medullary interstitium. The presence of
both urea and sodium in the interstitium increases the osmotic gradient for
water reabsorption and increases the concentration of the urine.
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| Uric Acid |
Uric acid is a product of the metabolism
(breakdown) of purines. Purines are chemicals that come from both the
breakdown of foods and nucleic acids (DNA) in the body. If uric acid levels in
the body are low, there are no symptoms. Doctors donŐt need to test for low
levels of uric acid.
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| White Blood Cell
Count (WBC) |
The total WBC count combines circulating
numbers of neutrophils, lymphocytes, monocytes, eosinophils and basophils.
Because neutrophils are the predominant leukocytic cell type, a high total WBC
count (leukocytosis) is generally due to an increase in this cell line.
However, absolute values of individual leukocytic cell lines (found by
performing a differential count and multiplying each cell line percentage by
the total WBC count) often provides more diagnostic specificity. Leukopenia
(decreased WBCs) is generally evident only with a decrease in neutrophils.
Leukocytosis and leukopenia occur with a variety of diseases. Normal ranges
for total WBC counts are printed by the VetScan HMT and should be similar to
textbook ranges. Differential counts may differ from textbooks and reference
labs because the VetScan HMT groups neutrophils, eosinophils and basophils
into one category (Granulocytes). Lymphocyte and monocyte values should be
similar to textbook values.
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