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Interpretation of Lab Results

Did you ever wonder what your doctor is checking for when he or she does your blood work? Most people know about cholesterol, but how about the BUN? I will attempt to explain the meaning of the blood work results.

The glucose (blood sugar) is a test for diabetes. Normal values are below 100. Diabetes is defined as a fasting blood sugar of greater than 126 on two separate occasions. Frequently it will be on the low side, but this is rarely of any significance. The value for the blood sugar will decrease if the test is not performed shortly after it is drawn. If it is very low, you may want to go by your doctor's office and get a finger stick for the blood sugar level, so that it can be analyzed immediately.

Sodium, chloride, potassium, and magnesium are called electrolytes, and they will sometimes become significantly abnormal with certain medications or different forms of lung, heart, or kidney disease. They are not related to the amount of salt you have in your diet. Water pills are most frequently implicated when the potassium is low. Some antidepressants and water pills can cause the sodium and chloride to be low.

Calcium and phosphorus are minerals in your bones, and they may be abnormal with certain hormonal diseases, or may be related to tumors in your bones. Phosphorous is difficult to test and is frequently out of the normal range. It is rarely a significant abnormality, but your physician can decide whether or not to pursue a mildly abnormal result.

The protein, albumin, A/G ratio and globulin results of your blood work are a measure of the liver function and will be abnormal with liver damage as seen in cirrhosis of the liver. The alkaline phosphatase, lactate dehydrogenase, gamma-glutamyl transferase, SGOT, and SGPT results are a measure of on going liver damage. Liver damage could be seen as a reaction to numerous medications, alcohol toxicity, hepatitis, tumors in the liver, or a number of viral illnesses. Frequently, one or two of these tests may be only slightly elevated which is not always significant, but may have to be repeated at a later date, after stopping medicines or avoiding alcoholic beverages.

The BUN, creatinine, and BUN/creatinine ratio are a very accurate measure of kidney function. The creatinine will be elevated with significant renal disease. A low serum creatinine or BUN is not usually a sign of disease.

Uric acid is a chemical in the body that may cause gout if it becomes elevated. Gout is a hereditary form of arthritis. A low uric acid is rarely a sign of disease.

Iron, iron binding capacity, and % saturation measure the amount of iron you have in your body. Results may be low because of poor dietary intake of iron, or from loss of blood from the body. A low serum iron is frequently seen in women that have heavy periods and have a diet low in iron. Bleeding from the gastrointestinal tract can also result in a low serum iron. This bleeding may be visible blood loss, or it may be occult, which means it is not readily apparent to the naked eye. It is important to check for blood in the stool if you iron is low. Occult blood in the stool can be tested with Hemocult slides (stool cards).

The desired level of total cholesterol is under 200. It is important to measure the HDL-cholesterol and the LDL-cholesterol. The HDL- cholesterol is the good cholesterol, and it is okay for it to be high. It seems to protect the heart and blood vessels from becoming clogged. One way to estimate your risk of having heart disease, is to divide the total cholesterol by the HDL-cholesterol. This ratio, ideally, should be less than 3.5, which would be associated with only one-half the risk of an average person having a heart attack. Your ratio can be improved by increasing the HDL-cholesterol, or decreasing the total cholesterol. This can usually be accomplished by regular aerobic exercise, such as walking, running, swimming, aerobic classes, or any exercise that maintains your heart rate at a fairly high level. You should attempt to maintain your heart rate at 70% or greater of your maximal predicted heart rate. Your predicted maximal heart rate is estimated by subtracting your age from 220. If you are 40 years old, your predicted maximal heart rate is 220-40=180. Therefore, 70% of this would be 126. You should try to SLOWLY get to the point where you can exercise for 30-60 minutes a day, keeping your heart rate above 125 beats per minute. Ideally, this should be done daily.

Your cholesterol level is determined by heredity, exercise, and diet. Unfortunately, heredity can be a very powerful influence on both the total cholesterol, LDL-cholesterol and the HDL-cholesterol level. Diet alone has minimal effect on cholesterol. Exercise has some effect particularly on increasing the HDL and lowering the total cholesterol and LDL-cholesterol. Diet and exercise together are the best non-medicinal treatment. Medications called statins have been a major advance in the treatment of high cholesterol. The LDL-cholesterol is used to decide whether or not someone should take a statin. It should be less than 130 in healthy individuals and less than 70 in individuals with diabetes or heart disease. Examples of statins are Mevacor, Lipitor, Pravochol and Crestor. Mevacor is presently the only generic statin. It works very well and is usually well tolerated.

It is important to realize that the cholesterol level may vary somewhat from day to day, and if you have an abnormal reading, it may need to be checked on several occasions to really get a good feel for its true value.

Triglycerides are another fat in your blood that are not quite as important as the cholesterol in the development of heart disease. The amount of this fat in your blood is influenced by your diet, and if it is elevated, you may need to get the test repeated when you are fasting. Eating within 14 hours of the blood test, may make the triglycerides go up.

The complete blood count (CBC) checks your white blood cells (WBCs) as well as your red blood cells. The red blood cells, hemoglobin, hematocrit, mcv, mch, mchc and rdw all are checks for different kinds of anemia.

Anemia is when your hemoglobin level is low, and you may manifest symptoms such as fatigue, headaches, and weakness.

Your WBCs are responsible for fighting off infection. They may decrease if you have certain viral infections, but they increase with most bacterial infections.

Platelets are involved in making your blood clot; occasionally, they will decrease to very low levels with certain viral infections. The Neutrophils, lymphocytes, monocytes, eosinophils, and basophils are specific types of WBCs, that are counted by hand as well as by the machine performing CBCs. The percentages of different types of WBCs will vary with many factors, such as viral infections, age, and even recent exercise. If you have allergies, the eosinophil count will frequently be elevated.

The TSH (thyroid stimulating hormone) is a hormone that is a very sensitive measure of your thyroid function. The thyroid gland is in the neck and produces a hormone called thyroxine, that is responsible for your metabolism. An under active thyroid will cause fatigue, constipation and depression, along with numerous other symptoms. An overactive thyroid will cause anxiety, weight loss, diarrhea, and many other symptoms. The TSH level is inversely related to your thyroid gland output of hormone. The brain monitors the thyroid hormone in the blood, and sends out more TSH when the thyroid hormone level gets low, stimulating the thyroid gland to produce more thyroid hormone. However, if the thyroid hormone level is high in the blood, the brain senses this and decreases the production of TSH. This is a signal for the thyroid gland to decrease the production of thyroid hormone.

The PSA stands for prostate specific antigen that is a screening test for cancer of the prostate gland. The American Cancer Society recommends that men over the age of 50 have a yearly PSA test. Men over the age of 40 should have a yearly PSA if they have a family history of prostate cancer, or if they are African-American.

FSH (follicle stimulating hormone) is a hormone secreted by a part of the brain known as the pituitary gland. It is frequently ordered in females to see if they are going through menopause. It will become elevated when menopause begins.

Many people will have one or more of the test results in the abnormal column. This is usually not significant, but should be discussed with the doctor.

The urinalysis is a test for evidence of a urinary tract infection, diabetes, kidney disease, or liver disease.

Other tests that may or may not have been performed, depending on your age and sex, are the EKG and PAP smear. The PAP smear will check for cancer of the cervix. The EKG will check for evidence of heart disease. If you were given Hemocult slides, be sure to complete them and send them back to the lab to check for cancer of the colon. It has been proven that you will reduce your chance of dying of colon cancer by 30% if you perform this simple test every year. Just try to do the best you can with the dietary restrictions. The only factor that is particularly important is to adhere to the recommendation of not taking over 250 mg of vitamin C for three days before completing the test.

The information provided above is offered as a community service about health-care issues and is not a substitute for individual consultation. Advice on individual problems should be obtained from your personal physician. This information is based on research by the author and represents his interpretation of the literature.

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Readers may send questions to our email address. This column is for informational purposes only and is not a substitute for professional or medical advice.

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