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Screening tests are very commonly used in medicine to look for diseases and other health problems that can be missed, even after the most careful physical exam. These tests are ordered by your doctor while you are healthy. This way, if you have a problem, it can be found and treated before you feel sick. They may be a bit inconvenient in terms of time and often come back normal. However, screening tests can be very useful in helping your doctor diagnose problems that would have otherwise been missed. They are one of the most important parts of your annual check-up.
Blood supplies all the cells in your body with nutrients and oxygen. At the same time, it removes waste products and carbon dioxide. Hundreds of different tests can be done on blood. A blood test at your annual physical usually screens you for only the following more common health problems.
CBC (Complete Blood Count) – Computers analyze and count each different part of your blood, including red blood cells, white blood cells and platelets (that help with blood clotting). A CBC can find conditions such as anemia, leukemia, or blood clotting problems.
ALT (Alanine Aminotransferase) – ALT is just one of many enzymes made by your liver. Elevated levels of any of the liver enzymes in your blood can be a sign of liver disease (such as hepatitis) or gall bladder disease.
Serum Creatinine – Creatinine is a waste material produced by active muscles. It is cleared from the blood into the urine by your kidneys. An abnormally high serum creatinine level means that your kidneys are unable to remove creatinine from your body, as is the case in kidney failure.
Lipids – Lipid tests measure levels of triglycerides, bad LDL cholesterol, and good HDL cholesterol. High levels of triglycerides and LDL cholesterol, and low levels of HDL cholesterol, are associated with heart attacks and strokes.
TSH (Thyroid Stimulating Hormone) – TSH is a chemical in your body that stimulates your thyroid gland to make thyroid hormone. Abnormal TSH levels warn your doctor that your thyroid is not working properly.
Fasting Glucose – This test measures the amount of glucose in your blood. A high level of glucose in your blood may mean that you have or are at risk of developing diabetes in the future. The Canadian Diabetes Association recommends that everyone over age 40 should be screened for diabetes.
Urine, produced by the kidneys, is a mixture of water, electrolytes and other substances. From the kidneys, urine travels down small tubes, called ureters, into the bladder. It is stored there until its release from the body via another small tube called the urethra.
Doctors can learn much about how your body is working by analyzing the contents of your urine. Red blood cells show that there has been bleeding somewhere along the urinary or genital systems. White blood cells suggest inflammation, such as a bladder infection. The presence of protein is used to monitor diabetes. As well, by measuring a variety of different substances in the urine, doctors are able to find 95 per cent of kidney diseases.
Stool, or feces, is formed mostly from undigested food. Your stool offers important clues about possible problems somewhere along your digestive system. This includes the esophagus (the tube from the throat to the stomach), stomach, small intestines, large intestines and rectum.
In a fecal occult blood test, stool is chemically analyzed for very small traces of blood. Even if there is so little blood in your feces that you can’t see it, this test will still be able to find it.
Blood found in the stool suggests that there has been bleeding somewhere along your digestive system. Such bleeding can be caused by many problems including ulcers and inflammatory bowel diseases as well as colon cancer. If blood is present, it will not be evenly distributed throughout the stool but deposited in small amounts here and there. For this reason, doctors usually ask that you give three samples of stool for analysis.
Health Canada currently recommends that everyone over the age of 50 be screened for fecal occult blood every two years.
The cervix, or opening into the uterus, is found at the end of the vagina (birth canal). Cancer of the cervix kills 8,000 women in North America each year. The Pap smear, invented by Dr. Papanicolaou, checks the cervix for suspicious cells that indicate cancer. A small swab takes cells from the cervix. These samples are placed on slides and looked at under a microscope. Pap smears are recommended annually for all women, starting when they become sexually active. Your doctor may choose to decrease the frequency of these tests after three negative tests in a row, or after the age of 65.
A mammogram is a test used to screen women for breast cancer. Each breast is squeezed between two plates, and low-dose x-rays are used to take a picture. These x-ray pictures are useful for doctors to identify changes within the breast that may or may not be cancer. Mammograms are particularly important since they can find lumps that cannot be felt during a physical exam. If suspicious changes are found in the breast tissue, your doctor will order more tests. This might include a breast biopsy, where a sample of the breast is sucked out with a needle. The sample is sent to a pathologist, who will study the tissue to see if changes are malignant (cancerous) or benign (not cancerous). All women over age 40 should have a mammogram done every one to two years.
The medical term for a bone scan is Dual Energy X-Ray Absorptiometry, or DEXA. This test uses low-dose x-rays to determine the density of bones. This is important because less dense bones are also weaker. Osteoporosis is the condition of having bones that are weaker and more likely to fracture than normal. If your bone scan detects that your bones are weak, your doctor can help you to include exercise and a healthy diet in 7your lifestyle. A variety of useful medications are available to help build stronger bones.
All men and women over the age of 65 should have a DEXA bone scan. It should be done earlier in people with risk factors for osteoporosis. Those more at risk include women who have gone through menopause and people with a family history of osteoporosis. Asian and European women with small body frames are also more likely to have weaker bones as they age.
Prostate Specific Antigen, or PSA, is a substance produced by a man's prostate gland, which is found just below the bladder. The PSA is released into the bloodstream. A PSA test measures the concentration of PSA in a sample of blood. Although an elevated level can be normal, it can also be associated with prostatitis (inflammation of the prostate gland) or prostate cancer.
There is some controversy in the medical world regarding PSA testing. Some doctors feel it is the best way to screen men for prostate cancer before it spreads to other parts of the body. Others believe that since PSA often inaccurately predicts prostate cancer, the information that it provides is not worth the anxiety associated with a falsely positive test. In addition, although many men will develop prostate cancer, most will die of another disease before their prostate cancer ever becomes fatal.
That being said, the Canadian Cancer Society recommends that all men over the age of 50 should at least discuss the PSA test with their family doctor. African men and men with a family history of prostate cancer should consider the test at an even earlier age.
Remember, screening tests are not perfect. They may be abnormal even if nothing is wrong. On rare occasions, they show a normal result when something is wrong. However, if a test result is abnormal, your doctor is alerted to a possible problem and can investigate. He or she can then make sure nothing is wrong. If something is wrong, you will receive appropriate treatment as fast as possible and before you feel sick. Your family doctor may also order additional screening tests if you have risk factors for specific health problems.
Book a full check-up with your family doctor at least once a year, and faithfully get your screening tests done. This way you and your doctor can work together to help you live a longer and healthier life.
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