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Lab Testing Guide
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BONE
Calcium -
a mineral necessary for many important bodily functions, including
bone formation, muscle contraction, and blood clotting. In addition,
calcium is involved in maintaining the stability of nerve cells.
Calcium levels in the blood are strictly controlled by various
substances called hormones. Abnormal blood calcium levels are associated
with bone diseases and a variety of other conditions.
Phosphorus -
a widely distributed element throughout the body. Approximately
85% of the body's phosphorus is found in bone in a complex with
calcium. Phosphorus plays an important role in bone formation,
carbohydrate metabolism (sugar formation and degradation), and
acid-base balance. Blood phosphorus levels fluctuate in a rhythmic
fashion during the day and are affected by your diet and some antacids.
Abnormal blood phosphorus levels are found in different types of
bone disease and several other disease states.
ELECTROLYTES
Chloride -
the anion (or negatively charged atom) of blood and other body
fluids. Chloride is involved in maintaining the normal amount of
water and the acid-base balance in body fluids. In general, the
serum level of chloride is closely associated with the level of
sodium. Serum chloride with higher or lower than normal can be
associated with metabolic acidosis and alkalosis and with diseases
of the gastrointestinal tract, kidney, and adrenal gland.
Potassium -
the main cation (positively charged atom) in human cells. Potassium
plays an important role in the functioning of nervous tissue and
in heart and muscle contraction. Serum potassium levels higher
or lower than normal can be caused by various conditions, including
diseases of the gastrointestinal tract, kidney, and adrenal gland.
Sodium -
the main cation (positively charged atom) of blood and other body
fluids. Sodium plays an important role in maintaining the normal
amount of water and the acid-base balance in body fluids. Within
the cells of the body, sodium is involved in nerve stimulation.
Serum sodium levels higher or lower than normal can be caused by
various conditions, including diseases of the gastrointestinal
tract, kidney, and adrenal gland.
HEART
AST (SGOT) -
an enzyme that originates in the heart, liver, muscle, kidney,
pancreas, spleen, lung, and red blood cells. Diseases involving
or affecting these tissues can cause elevations in serum AST levels.
Lactate
Dehydrogenase (LDH) - an enzyme found in human tissue, especially
the heart, kidney, liver, and muscle. Tissue damage can cause
the release of LDH into the blood. Conditions associated with
elevated blood LDH levels include myocardial infarction (heart
damage), certain types of anemia (caused by excessive red blood
cell destruction or vitamin deficiency), liver disease, progressive
muscular dystrophy, and cancer. High LDH levels may also be the
result of improper blood collection procedures.
KIDNEY
BUN (Blood Urea Nitrogen) - the main waste product produced
by the liver during the breakdown of proteins. More than 90%
of the urea is excreted by the kidneys. A variety of kidney diseases
can result in an increase in the BUN level. Elevated BUN levels
are also found in urinary tract obstruction, congestive heart
failure, gastrointestinal bleeding, and in individuals on a high-protein
diet. Low BUN values may be associated with severe liver damage,
acromegaly, and pregnancy. Diets low in protein and high in carbohydrates
may also be responsible for low BUN levels.
Creatinine-
a degradation product formed from creatine by muscles. The amount
of creatinine produced by muscles is relatively constant and is
dependent on muscle mass. Creatinine is released into the blood
at a constant rate and freely excreted by the kidneys. For this
reason, the creatinine test is frequently used to assess kidney
function. Elevated serum levels of creatinine may indicate kidney
disease.
LIPIDS
HDL -
high density lipoproteins. (Lipoproteins help regulate blood cholesterol
levels. They are a combination of lipids [fats] and proteins.)
HDL are considered "good" lipoproteins because they carry cholesterol
away from blood vessels to the liver where it is eliminated. HDL
are made up of approximately half protein and half lipid, and usually
contain 20% to 30% of total plasma cholesterol.
LDL-
low density lipoproteins. LDL are considered "bad" lipoproteins
because they tend to keep cholesterol in the blood vessels, forming
fatty deposits. LDL contain cholesterol as their major component
and normally contain 60% to 70% of plasma cholesterol.
VLDL -
very low-density lipoproteins. They contain large quantities of
triglyceride and represent, respectively, the transport form of
exogenous (dietary) and endogenous triglyceride. The VLDL normally
contain 10% to 15% of total plasma cholesterol.
Cholesterol,
Total -
total cholesterol (TC) levels should be the measurement used
for screening. Recent studies have established the total blood
cholesterol levels are independent and positively correlated
with risk for coronary heart disease.
Triglycerides -
lipids (fats) that account for 95% of the fat stored in tissue.
Elevated serum triglyceride levels are found in metabolic disorders,
kidney disease, liver disease, diabetes, and hypothyroidism (deficiency
of thyroid activity). When serum triglyceride and cholesterol levels
are both elevated, the probability of coronary artery disease is
increased.
LIVER
Alkaline Phosphatase - an enzyme found in almost all body
tissues. Its highest levels exist in the intestine, kidney, bone,
liver, and placenta. The enzyme form present in serum comes mainly
from the liver and bone. Measurements of serum alkaline phosphatase
are particularly useful in the evaluation of liver and bone disease.
Minor increases in the level of alkaline phosphatase are sometimes
observed during the normal aging process.
Bilirubin
Total - an orange-yellow bile pigment formed by the spleen
during the breakdown of hemoglobin. Bilirubin is transported
by a blood protein (albumin) to the liver for excretion in feces.
Elevated levels of serum bilirubin are often associated with
liver disease, bile duct obstruction, hemolytic (red blood cell
break-down) disease, and prolonged fasting.
PROTEIN
Albumin - the major protein of blood. Albumin plays an
important role in maintaining the water of blood in the blood
vessels (osmotic pressure transporting substances, and in nutrition.
It is made by the liver. Consequently, decreased albumin levels
may be associated with liver disease. Albumin levels may also
indicate general health and nutritional status.
Albumin/Globulin
(A/G) Ratio -
the calculated ratio of the levels of these two serum proteins.
A low A/G is found in certain liver diseases, kidney disease,
myeloma, and inflammation as well as other disorders.
Globulin -
one of the main protein groups found in the blood. The alpha- and
beta-globulins are synthesized by the liver, whereas the gamma-globulins
(antibodies that play an important role in the body's defense against
disease) are synthesized by blood cells. The level of serum globulin
is often elevated in liver disease, collagen diseases, myeloma,
etc.
Protein,
Total - the second most common substance in blood (water
is the most common). Serum proteins have many functions, including
the transport of other substances, immune defense, blood clotting,
and inflammation defense. Serum protein levels are useful for
evaluating nutritional status, infection, and various other disorders.
THYROID
Thyroxine (T4)- a hormone secreted by the thyroid gland. Thyroxine
is necessary for normal growth and development and plays an important role
in regulating the body's rate of metabolism (formation and breakdown of
biological substances). Measurement of serum thyroxine levels provides
an indication of general thyroid gland function. Various medications can
affect thyroxine levels.
Thyroid
Hormone Binding Ratio (THBR) (Triiodothyronine [T3] Uptake) -
this test assesses the number of unbound sites available on the
protein that transports thyroid hormones in the blood. This protein
is called thyroxine-binding globulin (TBG). Variations in the
serum levels of thyroid hormones can be caused by changes in
the level of TBG. The THBR test (in combination with the level
of thyroxine), is only useful in calculating the free thyroxine
index (FTI). Various medications can affect the results of this
test.
Free
Throxine Index (FTI) - a mathematical calculation that approximates
the level of free (unbound) thyroxin present in the blood. Only
the unbound portion of total thyroxine is active in the body;
therefor, this value indirectly estimates the level of biologically
active thyroxine.
Thyroid-stimulating
Hormones (TSH) - a hormone synthesized by the pituitary gland.
TSH regulates the formation and release of thyroxine and triiodothyroxine
(thyroid hormones) by the thyroid gland. In turn, TSH synthesis
is controlled by a hormone released by the hypothalamus. Serum
TSH measurements are excellent indicators of thyroid-pituitary-hypothalamus
system function. Various medications can affect the results of
this test.
OTHER
Glucose -
a sugar and a primary source of energy for bodily functions.
The level of blood glucose is strictly regulated by several hormones,
including insulin and glucagon. Serum glucose levels are useful
in diagnosing and evaluating diabetes mellitus, carbohydrate
metabolism disorders, and other disease states.
Iron -
an important component of hemoglobin, myoglobin, and many enzymes.
The serum iron level is a measure of the iron bound to transferrin,
the iron transport protein. Serum iron levels are decreased in
iron deficiency anemia, acute and chronic inflammatory disorders,
and during menstruation and pregnancy. Increased serum iron levels
have been found in pemicious anemia, acute hepatitis, and iron
overload disorders, such as iron poisoning, hemochromatosis, and
thalassemia.
Uric
Acid - a product formed mainly by the liver during the breakdown
of nucleic acids. Following handling by the kidney, uric acid
is excreted in the urine. Elevated serum uric acid have been
found to occur in kidney failure, gout, dehydration, endocrine
disorders, lead poisonings, and other disease states. Certain
drugs can also cause uric acid levels to be elevated. Decreased
uric acid levels may be associated with liver disease and kidney
tubule defects.
You can
be tested for all of the above by scheduling a Metabolic
Profile.
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