Interpreting Laboratory Data

 

LIPID PANEL   

                 

TRIGLYCERIDES          < 150 mg/dL (Recommended Range)

 

Triglycerides are the body’s storage form of fat.  Mostly found in adipose (fat) tissue, other triglycerides circulate in the blood to provide fuel for muscle work.  They are a measure of risk for heart disease independent of cholesterol levels.  Carbohydrates are an important dietary predictor of triglycerides.  Diets high in carbohydrates, especially sugar, lead to increase in triglycerides.  Exercise and weight loss is especially helpful in lowering triglycerides.  The metabolic changes that occur with exercise reflect better utilization of energy by body tissues.  Triglyceride levels over 150 mg/dL are associated with problems other than heart disease.  When triglycerides are extremely high (greater than 1000 mg/dL), there is a real risk of developing pancreatitis.

 

TOTAL-CHOL          <200 mg/dL

 

Cholesterol is a steroid that forms the membranes of cells in all organs and tissues; is used to make hormones; and form bile acids that absorb nutrients from food.  A small amount of the body’s cholesterol circulates in the blood in complex lipoproteins (HDL, LDL and VLDL).  A value below 200 mg/dL is considered desirable, 200 to 240 mg/dl is borderline high, and cholesterol above 240 mg/dL is considered high risk.  Total cholesterol is also related to carbohydrate intake in the presence of fat (the classic “meat and potato” diet.  The cholesterol levels may fluctuate as much as 10% from one month to another

 

HDL-CHOL          >or=40mg/dL

 

HDL is considered to be the “good cholesterol” because it removes excess cholesterol and disposes of it reversing the development of heart disease.  High HDL is good—the higher the better.  An HDL level below 40 mg/dL is associated with an increased risk of heart disease.  A desirable level of HDL is greater than 40 mg/dL.  The ideals level of HDL is 60 mg/dL but is more difficult for men to achieve than women.  Low HDL is not easily treated.  Since smoking can decrease HDL levels, quitting smoking (if you are a smoker) is a good way to increase HDL.  Exercise is the best way to increase HDL.  Moderate alcohol consumption has been reported to increase HDL as well.

 

LDL-CHOL          < 130 mg/dL

 

LDL carries cholesterol in the blood and is considered “bad” because it deposits excess cholesterol in the walls of blood vessels and contributes to heart disease.  Of all the forms of cholesterol in the blood, the LDL cholesterol is considered the most important in determining the risk of heart disease.  An LDL level less than 130 mg/dL is recommended but 100 mg/dL is ‘ideal’.  The first step in treating high LDL cholesterol is the adoption of a diet low in carbohydrates.  If diet and exercise does not adequately lower LDL, drugs may be prescribed.

 

CHOL/HDL RATIO          < 5.0

 

Used to assess overall coronary risk, where a lower ratio indicates lower risk.  A simple way to look at this ratio is that you want at least one quarter of the total cholesterol to consist of HDL.  The average ratio is considered between 3.5 to 4.5.  If you have an abnormally high HDL (which is good) it is possible that the total cholesterol will push above the 200 mg/dL threshold simply because HDL contributes to the total sum amount.  If you have high cholesterol levels and the ratio is below 4.0 there typically is no cause for alarm.

 

 

 

LIVER FUNCTION TESTS

 

BILIRUBIN          0.0-0.3 mg/dl

 

Bilirubin is an orange-yellow pigment formed when red blood cells break down (indirect bilirubin) and is then processed by the liver (direct).  An increased value may suggest a greater than normal breakdown of red blood cells or a condition where the liver is inflamed, obstructed, or damaged in some way and is not removing the normal amount of bilirubin.  Runner’s have a tendency to have slightly elevated bilirubin as blood cells are sheared when the foot strikes the pavement.

 

ALKALINE PHOSPHATASE          20-125 U/L

 

Alkaline phosphatase (ALP) is a protein that helps cells work.  Alkaline phosphatase is in high concentrations in the cells that make bone and in the liver and somewhat in the kidney and colon.  In the liver, it is found on the edges of cells that join to form bile ducts (tiny tubes that drain bile from the liver to the bowels where it is needed to help digest fats in the diet.  The presence of alkaline phosphatase in the blood can be the result of breakdown of liver cells (due to possible damage) or growth of bone (which may be normal or abnormal bone growth).  An increased value may suggest possible liver problems such as hepatitis or cirrhosis.  There are also a number of drugs that can affect the level of alkaline phosphatase.

 

AST or SGOT          2-50 U/L

(Aspartate Transaminase or Serum Glutamic Oxaloacetic Transaminase)

 

Aspartate transaminase (AST) is an enzyme found mostly in the heart, liver, and muscles and other areas of the body that are metabolizing glucose rapidly.  When a cell is injured or dies, AST is released into the blood stream.  The test primarily looks at liver status.  An increased value may suggest liver damage from a virus or alcohol consumption.  Very high levels or AST (more than 10 times the highest normal level) are usually due to acute hepatitis.  Values may take months to return to normal. In rare cases, some medicines can damage the liver; the doctor may suggest testing the liver from time to time if you are taking one of these.

 

GGT

(Gamma Glutamyl Transferase)          2-80 U/L

 

GGT is an enzyme found mainly in the liver; it is sensitive to changes in liver function.  When the liver is injured or obstructed, GGT levels rise.  It is the most sensitive liver enzyme in detecting bile duct problems.  GGT can also be used to screen for chronic alcohol abuse (it will be elevated in about 75% of chronic drinkers).  Many drugs and chronic use of Tylenol is known to elevate GGT.

 

LDH (Lactate Dehydrogenase)          100-250 U/L

 

Lactate dehydrogenase (LDH or LD) is an enzyme that is found in almost all body tissues but only a small amount of it is usually detectable in the blood.  When cells are damaged or destroyed, they release LDH into the bloodstream, causing blood levels to rise.  LDH is used as a general marker of cellular injury.  LDH can be used to look at liver problems, anemia, certain kinds of cancer and abnormal red blood cell destruction.

 

ALT/SGOT

(Alanine Transaminase/ Serum Glutamic Pyruvic Transaminase)          2-60 U/L

 

ALT is an enzyme found mostly in the liver; smaller amounts of it are also in the kidneys, heart, and muscles.  When the liver is damaged, ALT is released into the blood stream, usually before more obvious symptoms of liver damage occur, such as jaundice (yellowing of the eyes and skin).  An increased value may suggest liver damage from such diseases as hepatitis or alcoholism. 

 

CHLORIDE          98-110 mmol/l

 

Chloride is an electrolyte, important in maintaining the normal acid-base balance of the body and in keeping normal levels of water in the body.  Chloride generally increases or decreases in direct relationship to sodium.  The normal blood level remains steady, with a slight drop after meals.  Increased levels of chloride (hyperchloremia) usually indicate dehydration, but can also occur with any other problem that causes high blood sodium.  Decreased levels of chloride (hypochloremia) occur with any disorder that causes low blood sodium.  Hypochloremia also occurs with prolonged vomiting, gastric suction, chronic diarrhea, emphysema, or other chronic lung disease (respiratory acidosis), and with loss of base from the body (metabolic alkalosis).

 

CARBON DIOXIDE          21-33 mmol/l

 

When you breath, you bring in oxygen and release carbon dioxide.  Carbon dioxide is present in three forms in the blood (H2CO3, CO2 dissolved in blood, and bicarbonate (HCO3) the dominant form).  Bicarbonate is an electrolyte that is excreted and reabsorbed by the kidneys.  Its main job is to help maintain the acid-base balance (pH) in the body and secondarily to work with sodium, potassium, and chloride to maintain electrical neutrality at the cellular level.  High CO2 may be caused my emphysema, severe diarrhea or vomiting.  Low CO2 may be caused by diabetic ketoacidosis which can lead to kidney failure.

 

 

RED BLOOD CELL COUNT (RBC)

 

Red blood cell (RBC) count is a count of the actual number of red blood cells per volume of blood.  Red blood cells are reported as millions in a microliter of blood (4,250,000/µL or 4.25x10^6/µL) or as millions in a liter of blood (4.25x10^12/L).

 

HEMOGLOBIN          13.2-17.1 g/dl

 

Hemoglobin measures the amount of oxygen-carrying protein in the blood.  The ‘heme’ contains the iron component and the characteristic red pigment of blood and the ‘globin’ is formed from a number of amino acids.  Because oxygen is attached and transported by hemoglobin, it is important to know how much you have.  Low hemoglobin levels can be an indicator of anemia, causing fatigue and weakness.  High levels may be a compensatory response to smoking.

 

 

HEMATOCRIT          38.5-50.0%

 

Hematocrit is a measurement of the proportion of blood that is made up of red blood cells expressed as a percentage.  For example, a hematocrit value of 40% means that 40% of the blood supply is red blood cells.  The hematocrit rises when the number of red blood cells increases or when the blood volume is reduced, as in dehydration.  The hematocrit falls to less than normal, indicating anemia, when the body decreases its production of red blood cells or increases its destruction of RBCs.

 

MCV          80.0-100 FL

 

Mean corpuscular volume is a measurement of the average size of the RBCs.  An increased MCV may suggest anemia resulting from insufficient folic acid, vitamin B-12, or alcoholism.  A decreased MCV and MCHC may be due to anemia resulting from a lack of iron.

 

MCH          27.0-33.0 PG

 

Indicates the weight of the hemoglobin within a RBC.  Mean corpuscular hemoglobin (MCH) is a calculation of the amount of oxygen-carrying hemoglobin inside the RBCs.

 

 

PARATHYROID FUNCTION

 

CALCIUM          8.5-10.4 mg/dl

 

Calcium is one of the most important minerals in the body.  About 90% of it is stored in bones, and most of the rest circulates in the blood.  Roughly, half of the calcium is ionized and is metabolically active.  If the level in the blood is abnormally low, the body will draw calcium from the bones and teeth.  An increased value may suggest a significant dietary intake of foods high in calcium such as milk, extended bed rest, or kidney problems.  A decreased value may suggest reduced amounts of albumin, a reduced dietary intake of calcium, pregnancy, problems with the kidney or the parathyroid gland.

 

PHOSPHORUS (inorganic)          2.5-4.5 mg/dl

 

Normally, only a very small amount of inorganic phosphate is present in the blood.  Phosphates are vital for energy production, muscle and nerve function, and bone growth.  They also play an important role in maintaining acid-base balance.  Most phosphorus comes from dietary sources such as beans, peas and nuts, cereals, dairy products, eggs, beef, chicken, and fish.  The body maintains phosphorus/phosphate levels in the blood by regulating how much it absorbs from the intestines and how much it excretes from or conserves in the kidneys.  An increased value may suggest a disease of the bones, kidney disease, a significant increase of Vitamin D, or underproduction of parathyroid hormones.  A decreased value may be the result of alcoholism, excessive production of parathyroid, kidney problems or too little Vitamin D. 

 

 

ELECTROLYTES

SODIUM          135-146 mmol/l 

Sodium is the principal electrolyte in the blood.  Like potassium and chloride, it is important in cell osmosis and the transmission of nerve impulses.  A decreased value may suggest excessive sodium loss from diarrhea, kidney problems, or excessive sweating.  It may suggest problems related to the adrenal gland, inadequate salt in the diet (rare in the US) or heart failure.  Even with dehydration it is quite difficult to reduce the amount of sodium circulating in our blood without fundamental underlying health problems.  Most sodium comes from table salt.  Most Americans average 4,000-5,000 mg of sodium per day, when one tenth of that (500mg) is all that is needed.

 

POTASSIUM          3.5-5.3 mmol/l

 

Potassium is the principal electrolyte in intracellular fluid, and is important for conducting nerve impulses, muscle contraction, and cellular osmosis.  An increased value (hyperkalemia) may suggest failure of the kidneys, liver disease, or diabetes.  A decreased value (hypokalemia) can be the result of certain endocrine disorders or the result of fluid loss.  Anything that excessively reduces body fluids such as diuretics, laxatives, diarrhea, or vomiting can lower levels.  The most common cause of hyperkalemia is kidney disease, and certain drugs.  Hypokalemia can occur if you have diarrhea and vomiting, or if you are sweating excessively.  A number of fruits, vegetables, and meats are good sources of potassium.