Overview
Laboratory tests are tools helpful in evaluating the health status of an individual. It is important to realize that laboratory results may be outside of the so-called "normal range" for many reasons. These variations may be due to such things as race, dietetic preference, age, sex, menstrual cycle, degree of physical activity, improper collection and/or handling of the specimen, non-prescription drugs (aspirin, cold medications, vitamins, etc.), prescription drugs, alcohol intake and a number of non-illness-related factors. Any unusual or abnormal results will be discussed with you. It is not possible to diagnose or treat any disease or problem with one blood test alone. It can, however, help you to learn more about your body and detect potential problems in early stages when treatment or changes in personal habits can be most effective.
Our lab, like almost all labs, sets the normal result range for a particular test so that 95% of our healthy patients fall within the normal range. That means that 5% of our healthy patients fall outside of the normal range, even when there is nothing wrong with them. Thus an abnormal test does not necessarily mean that there is something wrong with you. Statistically if you have 20 or 30 individual tests run as part of a panel, chances are 1 or 2 will be slightly outside the normal range. Part of what we do for you is to interpret whether or not these changes are significant.
Your Results
You will receive notification of all lab results. We do this via a service called "Lab Calls". The service works as follows: You will be given a card at your appointment that has your identification number and PIN. Within 2 weeks of your visit you will get an automated phone call to notify you that a message about your lab results is ready to be retrieved. You can then confidentially phone or use the internet to get a report on your results. Occasionally we will call you to explain a result. This DOES NOT necessarily mean the result is worrisome, but rather that it requires a more lengthy explanation! Please be patient awaiting your notification. We use an excellent local laboratory that prides itself on timely, accurate results. Occasionally a test will be repeated for quality control, and this takes more time. If you have not heard from us by 3 weeks after your visit, please contact us.
To help you understand your results, you might want to look at the information below. This review is a brief summary and is not intended to be comprehensive or replace discussion of your results with you, should they be significantly abnormal.
Complete Blood Count
This is an actual count of the platelets, red and white blood cells, as well as a measurement of the hemoglobin (oxygen carrying component) of the blood. The size of the red blood cells, and the types of white blood cells is also reported. By looking at the values, we can determine if you are anemic, have signs of infection, or may have another blood disease.
Glucose
This is a measure of the sugar level in your blood. High values are associated with eating before the test, and diabetes. The normal range for a fasting glucose is 60 -109 mg/dl. According to the 1999 ADA criteria, diabetes is diagnosed with a "fasting" plasma glucose of 126 or more, on at least two occasions. A precursor, Impaired Fasting Glucose (IFG) is defined as a reading of fasting glucose levels of 110 – 125
Electrolytes
These are your potassium, sodium, chloride, and CO2 levels.
Potassium is controlled very carefully by the kidneys. It is important for the proper functioning of the nerves and muscles, particularly the heart. Any value outside the expected range, high or low, requires medical evaluation. This is especially important if you are taking a diuretic (water pill) or heart pill (Digitalis, Lanoxin, etc.).
Sodium is also regulated by the kidneys and adrenal glands. There are numerous causes of high and low sodium levels, but the most common causes of low sodium are diuretic usage, diabetes drugs like chlorpropamide, and excessive water intake in patients with heart or liver disease.
CO2 reflects the acid status of your blood. Low CO2 levels can be due to increased acidity from uncontrolled diabetes, kidney disease, metabolic disorders, or low CO2 can be due to chronic hyperventilation.
Waste Products
Blood Urea Nitrogen (BUN) is a waste product produced in the liver and excreted by the kidneys. High values may mean that the kidneys are not working as well as they should. BUN is also affected by high protein diets and/or strenuous exercise which raise levels, and by pregnancy which lowers it.
Creatinine is a waste product largely from muscle breakdown. High values, especially with high BUN levels, may indicate problems with the kidneys.
Uric Acid is normally excreted in urine. High values are associated with gout, arthritis, kidney problems and the use of some diuretics.
Enzymes
AST, ALT, SGOT, SGPT, and GGT and Alkaline Phosphatase are abbreviations for proteins called enzymes which help all the chemical activities within cells to take place. Injury to cells release these enzymes into the blood. They are found in muscles, the liver and heart. Damage from alcohol and a number of diseases are reflected in high values.
Alkaline phosphatase is an enzyme found primarily in bones and the liver. Expected values are higher for those who are growing (children and pregnant women) or when damage to bones or liver has occurred or with gallstones. Low values are probably not significant.
GGT is also elevated in liver disease, particularly with obstruction of bile ducts. Unlike the alkaline phosphatase it is not elevated with bone growth or damage.
AST/SGOT , ALT/ SGPT are also liver and muscle enzymes. They may be elevated from liver problems, hepatitis, excess alcohol ingestion, muscle injury and recent heart attack.
LDH is the enzyme present in all the cells in the body. Anything which damages cells, including blood drawing itself, will raise amounts in the blood. If blood is not processed promptly and properly, high levels may occur. If all values except LDH are within expected ranges, it is probably a processing error and does not require further evaluation.
Bilirubin is a pigment removed from the blood by the liver. Low values are of no concern. If slightly elevated above the expected ranges, but with all other enzymes (LDH, GOT, GPT, GGT) within expected values, it is probably a condition known as Gilbert's syndrome and is not significant.
Proteins
Albumin and Globulin measure the amount and type of protein in your blood. They are a general index of overall health and nutrition. Globulin is the "antibody" protein important for fighting disease. A/G Ratio is the mathematical relationship between the above.
Blood Fats
Cholesterol is a fat-like substance in the blood which, if elevated has been associated with heart disease. Less than 200 is recommended by the National Heart, Lung, and Blood Institute.
Total Cholesterol: A high cholesterol in the blood is a major risk factor for heart and blood vessel disease. Cholesterol in itself is not all bad, in fact, our bodies need a certain amount of this substance to function properly. However, when the level gets too high, serious problems can result. Levels of 200 or more are too high for good health. Levels of 240 and above are considered high risk, and may indicate the need for cholesterol lowering medication. A low fat diet and regular exercise are recommended. As the level of blood cholesterol increases, so does the possibility of plugging the arteries due to cholesterol plaque build-up. Such a disease process is called "hardening of the arteries" or atherosclerosis. When the arteries feeding the heart become plugged, a heart attack may occur. If the arteries that go to the brain are affected, then the result is a stroke.
There are two major kinds of cholesterol, High Density Lipoprotein (HDL) and Low Density Lipoprotein (LDL).
LDL Cholesterol is considered "bad cholesterol" because cholesterol deposits form in the arteries when LDL levels are high. An LDL level of less than 130 is recommended, 100 is ideal, values greater than 160 are considered high risk and should be followed up. Those persons who have established coronary or vascular disease may be instructed to get their LDL Cholesterol well below 100.
HDL cholesterol is a "good cholesterol" as it protects against heart disease by helping remove excess cholesterol deposited in the arteries. High levels seem to be associated with low incidence of coronary heart disease. The ratio of Total Cholesterol to HDL is useful in judging the significance of the cholesterol level. The lower the ratio, the better. Therefore, a cholesterol over 200 may be okay if the HDL is also higher than average. Your lab slip will show the breakdown and the ratio.
Triglyceride is fat in the blood which, if elevated, has been associated with heart disease, especially if over 500 mg. High triglycerides are also associated with pancreatitis. Triglyceride levels over 150 mg/dl may be associated with problems other than heart disease. Ways to lower triglycerides: 1) weight reduction, if overweight; 2) reduce animal fats in the diet: eat more fish; 3) take certain medications; 4) get regular aerobic exercise; 5) decrease alcohol and sugar consumption—alcohol and sugar are not fats, but the body can convert them into fats then dump those fats into your blood stream.
Minerals
Calcium is controlled in the blood by the parathyroid glands and the kidneys. Calcium is found mostly in bone and is important for proper blood clotting, nerve, and cell activity. An elevated calcium can be due to medications such as thiazide type diuretics, inherited disorders of calcium handling in the kidneys, or excess parathyroid gland activity or vitamin D. Low calcium can be due to certain metabolic disorders such as insufficient parathyroid hormone; or drugs like Fosamax or furosemide type diuretics.
Phosphorus is also largely stored in the bone. It is regulated by the kidneys, and high levels may be due to kidney disease. When low levels are seen with high calcium levels it suggests parathyroid disease, however there are other causes. A low phosphorus, in combination with a high calcium, may suggest an overactive parathyroid gland.
Thyroid
There are 2 types of thyroid hormones easily measurable in the blood, thyroxine (T4) and triiodothyronine (T3). For technical reasons, it is easier and less expensive to measure the T4 level, so T3 is usually not measured on screening tests.
Thyroxine (T4)
This shows the total amount of the T4. High levels may be due to hyperthyroidism, however technical artifact occurs when estrogen levels are higher from pregnancy, birth control pills or estrogen replacement therapy. A Free T4 (see below) can avoid this interference.
Free Thyroxine Index (FTI or T7)
A mathematical computation allows the lab to estimate the free thyroxine index from the T4 and T3 Uptake tests. The results tell us how much thyroid hormone is free in the blood stream to work on the body. Unlike the T4 alone, it is not affected by estrogen levels.
Free T4
This test directly measures the free T4 in the blood rather than estimating it like the FTI. It is a more reliable , but a little more expensive test.
Free T3
This test measures only the portion of thyroid hormone T3 that is "free", that is, not bound to carrier proteins.
Thyroid Stimulating Hormone (TSH)
This protein hormone is secreted by the pituitary gland and regulates the thyroid gland. A high level suggests your thyroid is underactive, and a low level suggests your thyroid is overactive.
Glycohemoglobin
(Hemoglobin A1 or A1c, HbA1c) :
Glycohemoglobin measures the amount of glucose chemically attached to your red blood cells. Since blood cells live about 3 months, it tells us your average glucose for the last 6 - 8 weeks. A high level suggests poor diabetes control. Standardization for glycohemoglobin from lab to lab is poor, and you cannot compare a test from different labs unless you can verify the technique for measuring glycohemoglobin is the same
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