Articles Archive

• Hepatitis C testing: Who is at risk?
• Hepatitis C testing: What tests?
• What is Her-2 testing?
• What is systemic lupus erythematosus and how is it diagnosed?
• What tests are used to diagnose anemia?
• What is diabetes, and what laboratory tests are used for diagnoses?
• What tests are used to diagnose a heart attack or acute myocardial infarction (AMI)?
• What is Human Immunodeficiency Virus (HIV) and how is it diagnosed?
• What genetic tests are available to rule out birth defects and other genetic problems?
• What laboratory procedures test for Thyroid function?
• What is CA 125 and what does it tell my physician?
• What is the Prostate Specific Antigen?

Hepatitis C testing: Who is at risk?

Hepatitis C virus (HCV) infection is the most common chronic bloodborne infection in the United States. Current surveys indicate that an estimated 3.9 million Americans, representing 1.8% of the population, have been infected with HCV. The Centers of Disease Control and Prevention recommend that the following persons, based on their risk of exposure, should be tested routinely for HCV infection:

• Persons who have injected illegal drugs, including those who have only injected once many years ago, and do not consider themselves a drug user.
• Persons who received clotting factor concentrates before 1987.
• Persons who have been on long-term hemodialysis.
• Persons with persistently abnormal alanine aminotransferase (ALT).
• Persons who have received transfusions or organ transplants.
• Persons who have been notified that they received blood from a donor who later tested positive for HCV infection.
• Persons who have received a blood or blood product transfusion before July 1992.
• Health care, emergency medical, and public safety workers after needle sticks or other exposure to HCV-positive blood or body fluid.
• Children born to HCV-positive women.
• Persons with multiple sexual partners.

Hepatitis C frequently causes an asymptomatic, but chronic infection of the liver. Persons with HCV usually exhibit no symptoms for about 20 years, but in many cases the disease causes serious liver injury. The federal government estimates that about 7% of those thought to be infected with HCV contracted the disease either through transfusion of infected blood products, the remaining 93% are from the other mentioned high risk groups.

Hepatitis C testing: What tests?

Antibody tests are used to screen for HCV and to confirm a diagnosis. The initial screen test is an anti-HCV by enzyme immunoassay (EIA). Eighty percent of patients who have been exposed and have "caught" HCV will test positive within 15 weeks of exposure. On rare occasions it may take as long as 9 months for the patient to build up detectable levels of anti-HCV in the blood. All positive screens should be confirmed with supplemental tests, usually an antibody test using recombinant assay methods (anti-HCV by RIBA method). Persons who are positive for the confirmatory test are considered HCV-positive.

After acute infection, 15% - 25% of persons appear to resolve their infection without further complications. Unfortunately 75% - 85% of patients develop chronic HCV infection. However, antibody testing does not distinguish between acute, chronic, or resolved infection. Viral load testing is used to follow the effectiveness of treatment. Another problem with HCV testing is that at times during the course of acute and chronic disease state, the liver enzymes and viral antigens (HCV-RNA) may be only intermittently positive. Therefore, a single negative test may be inconclusive and does not indicate that the patient is free of the HCV infection. HCV viral load testing will continue through out treatment and in the years following.

What is Her-2 testing?

Surgeons and oncologists have been interested in Her-2 because it provides information on the prognosis and the effectiveness of chemotherapy for patients with breast cancer. It may also be important in predicting the patient's responsiveness to therapy using antibodies to Her-2.

It is sometimes called Her-2 neu (pronounced her to new) because of its similarity to the neu rat gene, Her-2 is an oncogene that encodes for a receptor found on the membranes of certain cells. This receptor shows similarities to the epidermal growth factor receptor. Circulating growth factors attach to the cell surface receptors and signal the nucleus to divide. The more the Her-2 oncogene is amplified, the more receptors are formed and the more the tumor is encouraged to grow. Her-2 is overexpressed in many different types of human cancers, including breast cancer, lung cancer, ovarian cancer, gastric cancer, and oral cancers. Currently, most of the clinical research is being done on breast cancer. In the past, the over-expression of Her-2 in breast cancer has been associated with poor overall patient survival in certain populations. Over-expression on breast cancer cells may also be associated with tumor resistance to certain cancer chemotherapy agents and increased sensitivity to other chemotherapy agents.

In 1998 the FDA approved the use of antibodies to Her-2 to treat patients who over-express this gene. Clinical trials seems to be showing that anti-Her-2 antibodies inhibits tumor cell growth, increases sensitivity to chemotherapeutic agents and enhances the body's own tumor fighting abilities. Preliminary studies suggest that this is an important new treatment option.

 What is systemic lupus erythematosus and how is it diagnosed?

Systemic lupus erythematosus (SLE) is an auto-immune disease, where antibodies made to destroy infection, instead destroy the patient's own cells. It is estimated that 500,000 Americans have been diagnosed with SLE, although surveys indicate that that number may be significantly low. About 90% of cases are women, most of who are diagnosed while in the childbearing ages.

SLE has many symptoms, which can have a sudden onset, or can increase slowly over many years. Examples of symptoms are arthritic pain, fever, skin rashes, anemia, fatigue, loss of appetite, nausea, weight loss, chest pain, bruising, photosensitivity, hair loss, facial rash, mouth or nose ulcers, and loss of concentration. The only predictable fact about SLE is that it is unpredictable. The combination of symptoms and course of disease being different in each patient makes laboratory testing important to the diagnosis.

In patients with SLE, a faulty interaction between T and B white blood cells result in the production of autoantibodies called antinuclear antibodies (ANA), that attack the nucleus and DNA of the patient's healthy cells. A high level of ANA is found in 98% of SLE patients. While this laboratory test is a strong indicator of SLE, other disease states also cause a positive ANA, so further testing will be required.

Because of the seemingly random symptoms, SLE can be difficult to diagnose, and may take years of work with a physician before the symptoms and other diagnostic tests yield a diagnosis. No single laboratory test can prove or disprove SLE; therefore the initial screen will include many tests. These may include a CBC, ANA, a syphilis test, blood chemistries and an erythrocyte sedimentation rate. A physician uses laboratory results and a patient's clinical history to establish a diagnosis of lupus. Diagnosing lupus is often a challenge.

What tests are used to diagnose anemia?

What is anemia? Anemia is a condition in which the hemoglobin content of your blood is low. Hemoglobin is the protein inside your red blood cells that carries oxygen to the tissues. It also carries carbon dioxide to the lungs where it is exhaled. If you are anemic you may have pale skin, be chronically tired, and be short of breath when exercising or feel light-headed and faint. Usually the first test your physician will order if anemia is suspected is a complete blood count (CBC) to see if your hemoglobin concentration is decreased. The following is a description of the types of tests done in the laboratory to help diagnose and find the cause of anemia.

The most common laboratory screening test is the complete blood count or CBC. This test analyzes the red cells, white cells, and platelets in your blood. The information from this test will assist the physician in determining if you are anemic, what type of anemia you have, or if you have leukemia, infection or inflammation. If this test is abnormal your physician may order other tests to help pin point your problem. A CBC is performed on a blood specimen using a special analyzer. The analyzer counts the numbers of red cells (RBC), white blood cells (WBC), and platelets. It also measures your hemoglobin concentration, your hematocrit (ratio of the red cell volume to the total volume of blood) and the size of your red cells. Some analyzers will count the number of different types of white cells. This is helpful in determining if you have a specific type of infection or malignant condition. If any of these tests are abnormal, your physician will probably order further testing. Since blood cells are made in your bone marrow, in some cases, the physician may order a bone marrow. In this test a small amount of bone marrow is withdrawn using a needle. The marrow is then stained and examined under a microscope.

Iron deficiency anemia is one of the most common anemias in women. However, not all anemias are caused by iron deficiency. If a CBC result shows that your red cell count and hemoglobin are low and the red cells are small, you might have this anemia. Further testing is necessary to find the cause of your anemia. There are several different types of tests that can be done to evaluate the amount of iron in the body. Usually these are ordered together to help the physician determine if you are iron deficient and why. If you are iron deficient, the physician must determine why and correct the problem. Is it because you have a diet poor in iron? Are you bleeding from the digestive tract? Are you losing a lot of blood during your menstrual period? If you are taking a vitamin with iron, you need to let your physician know since this will complicate interpretation of the test results.

Vitamin B12 and Folic Acid are two chemicals needed by the body to make new cells. If you are not absorbing enough of these, you may become anemic and experience other problems. The kind of anemia caused by folic acid or vitamin B12 deficiency is called megaloblastic anemia.

Vitamin B12 is also known as cobalamin. You should include 5 - 7 m g of vitamin B12 per day in your diet. This amount is available in a mixed diet but if you are a strict vegetarian, you will not be consuming enough by food alone. Pregnancy may lead to a deficiency if the mother has a poor diet. Vitamin B12 is stored in the body and it takes several years to develop a deficiency if you do not consume enough.

Folic acid is found in most foods and is synthesized by bacteria in the gut. Overcooking destroys folic acid. The daily dietary recommendation if 200 m g per day. The liver stores enough folic acid for 3-6 months if there is no folic acid in the diet. There is an increased need for folic acid in pregnancy and during breast feeding.

In some cases there is a reason to do another test called a Schilling Test. This test will help the physician determine if your vitamin B12 deficiency is due to the absence of a factor in the stomach (intrinsic factor) that must be present for you to absorb the vitamin B12 in the intestine. If this factor is missing, you have pernicious anemia. You will be given either regular injections of vitamin B12 or a nasal spray that contains vitamin B12 because you cannot absorb the vitamin in the intestine. In the Schilling test you are given a dose of vitamin B12 by mouth and an injection of B12 several hours later. You collect all your urine for 24 hours and a blood sample will be drawn. The laboratory will test both your urine and blood.

What is diabetes, and what laboratory tests are used for diagnoses?

Diabetes mellitus occurs when an individual has a high blood sugar. It occurs because of a problem with insulin, which is a hormone produced by the pancreas. When insulin is not produced or used correctly by the body, sugar cannot get into the cells and produce energy.

There are several types of diabetes mellitus, which include insulin-dependent diabetes mellitus (Type I or juvenile diabetes), non-insulin-dependent diabetes mellitus (Type II or maturity onset diabetes) and gestational diabetes mellitus. Type I diabetes mellitus is characterized by a lack of insulin. Type II diabetes mellitus usually develops after the age of 40 and often can be controlled by diet, weight loss, and exercise. Sometimes drugs or insulin are also needed. Gestational diabetes can occur during pregnancy. If diabetes mellitus is not treated, the individual may develop vascular disease or disease of the nerves. These diseases may lead to complications such as blindness, kidney disease and amputations.

Gestational diabetes mellitus is a form of diabetes characterized by a deficiency of insulin during pregnancy. The condition usually disappears after the birth of the child and the mother returns to normal.

The following are laboratory tests for diabetes:

Blood glucose test: If your physician suspects that you may have diabetes, he will order a blood glucose test. The blood specimen must be taken after a fast of 8-hours. In a patient untreated for diabetes the fasting blood glucose level is high. Generally a value greater than 126 mg/dL on more than one occasion is required for a diagnosis of diabetes. If your blood glucose is high or there is sugar in the urine, further tests may be done.

Oral glucose tolerance test (OGTT): This test may be done if the blood glucose test is abnormal or if glucose is found in the urine. You will be given a solution to drink that contains a high level of carbohydrate. Your blood will be drawn periodically after that to see if your blood sugar goes back to normal after a brief time. In diabetes, there is not enough insulin produced or the glucose cannot get into the cells. Therefore the glucose level remains high in the blood for two hours or more. For a diagnosis of diabetes, the specimen taken at 2 hours and one other specimen must have a glucose value of 200 mg/dL or higher.

Insulin test: This test may be done in those individuals who are older when they develop diabetes-like symptoms and it is suspected that they may have type II diabetes. The insulin level may be high indicating that the cells cannot use the insulin to get the glucose into the cells.

What tests are used to diagnose a heart attack or acute myocardial infarction (AMI)?

During an AMI, the cells in the heart die when there is a lack of blood supplied to the myocardial tissue. This usually occurs when the coronary arteries become blocked and cannot supply blood the heart muscle. When cells die they release their contents which find their way into the blood. By measuring the amount of these substances in the blood, it can be determined if you had a heart attack.

Cardiac markers in the blood are used to help in the diagnosis of a heart attack. Cardiac markers that are currently being used are myoglobin and Troponin-I and CK-MB, which is a specific enzyme released when cardiac muscle dies. Some of these proteins immediately begin to increase in the blood while others do not increase for hours after the heart attack. Some remain increased in the blood longer than others. Therefore it depends on when you first experienced the symptoms of a heart attack as to which tests your physician will order. It is common for a patient to remain in the emergency room for several hours after the attack and have repeated blood samples drawn to see if the proteins and enzymes eventually increase.

What is Human Immunodeficiency Virus (HIV) and how is it diagnosed?

Human Immunodeficiency Virus (HIV) causes AIDS. Patients are at risk of acquiring or transmitting HIV when they are infected with other sexually transmitted diseases such as chlamydia or gonorrhea. When genital ulcers such as those produced by syphilis or herpes are present, the patient is at a greater risk for acquiring or transmitting this virus.

To prevent the spread of HIV, counseling and early diagnosis are important. Testing for HIV antibody is highly accurate. HIV antibody is a substance that can be detected in the person's blood when he or she has been exposed to the virus. Before a person is considered "positive" for HIV, the blood sample must produce a "positive" result for both a screening test and a confirmatory test. Antibodies usually appear about 3 months after infection with HIV, but sometimes may take up to 6 months. If the test is negative at 3 months, it must be repeated at 6 months after exposure.

What laboratory procedures test for Thyroid function?

These tests are performed to help in the diagnosis of thyroid disorders such as hyperthyroidism or hypothyroidism. Hyperthyroidism represents an overactive thyroid gland and is characterized by the production of excess amounts of thyroid hormones, T₄ and T₃. Hypothyroidism represents an underactive thyroid gland and is characterized by decreased production of thyroid hormones, T₄ and T₃. In a normal individual a hormone produced by the pituitary gland, thyroid-stimulating hormone (TSH), balances the levels of thyroid hormones. If insufficient thyroid hormones are present in the blood, TSH is produced which tells the thyroid gland to produce more thyroid hormones. Conversely, if an excess of thyroid hormones is present in the blood, TSH is not produced and the thyroid gland slows production of thyroid hormones. Thyroid disorders occur when there is a problem in maintaining this balance. The following is a discussion of the most commonly ordered thyroid function tests.

Thyroid-stimulating hormone (TSH) is frequently the first test ordered to determine if an individual has a thyroid disorder. This laboratory test measures the level of TSH in an individual's blood. TSH is the pituitary hormone that tells the thyroid gland to produce more thyroid hormones, T₄ and T₃. Typically, TSH will be decreased in hyperthyroidism (excess levels of T₄ and T₃), but increased in hypothyroidism (decreased levels of T₄ and T₃). The TSH test is also used to monitor a patient's response to treatment for either hyperthyroidism or hypothyroidism.

Free Thyroxine (T₄) measures the free T₄ in the blood. In the blood the majority of T₄ circulates bound to proteins and only a small amount is unbound or free. The free T₄ is responsible for the hormone's action. In hyperthyroidism the Free T₄ is increased, while in hypothyroidism the Free T₄ is decreased.

Free Triiodothyronine (T₃) measures the amount of free T₃ in the blood. In the blood the majority of T₃ circulates bound to proteins and only a small amount is unbound or free. The free T₃ is responsible for the hormone's action. The measurement of Free T₃ provides similar information to the physician as the Free T₄, helping to identify hyperthyroidism and hypothyroidism.

Total Thyroxine (T₄) measures the total amount of T₄ (protein-bound and free) that is circulating in the blood. It is used together with the Triiodothyronine T₃ Uptake (T₃UP) to rule out the possibility of hyperthyroidism or hypothyroidism in conditions associated with decreased or increased protein levels such as acute or chronic illness, pregnancy or use of oral contraceptives. For example, an elevated Total T₄ and elevated T₃UP indicates hyperthyroidism while an elevated Total T₄ and decreased T₃UP indicates a condition associated with increased protein levels like pregnancy. On the other hand, a decreased Total T₄ and decreased T₃UP indicates hypothyroidism while a decreased Total T₄ and increased T₃UP indicates a condition associated with decreased protein levels like liver disease.

Total Triiodothyronine (T₃) measures the total amount of T₃ (protein-bound and free) that is circulating in the blood. Total T₃ results provides similar information as Total T₄.

Triiodothyronine T₃ Uptake (T₃UP or T₃U) measures the specific thyroid hormone binding proteins in the blood and is called T₃ Uptake because T₃ is used in the test procedure. The measurement of T₃ Uptake is used to help determine if elevated T₃ or decreased T₃ levels are due to changes in protein levels and not the result of thyroid disease. If the test result comes back "decreased T₃UP", this indicates decreased uptake of T₃ in the test procedure and is caused by increased levels of thyroid hormone binding proteins. Likewise, if a test result comes back "increased T₃UP", this indicates increased uptake of T₃ in the test procedure and is caused by decreased levels of thyroid hormone binding proteins. The T₃UP should always be used in conjunction with a Total T₄ or Total T₃ to assess an individual's thyroid status in the presence of changes in protein levels.

What genetic tests are available to rule out birth defects and other genetic problems?

Triple Marker screening or a Trisomy. A pregnant woman's blood specimen may be tested for the presence of three substances produced by the fetus. These serve as a screen to help detect the presence of fetuses at high risk of having a chromosome abnormality. Many chromosomally abnormal fetuses produce more or less of the three substances than does the chromosomally normal fetus. The three substances found in the maternal blood serum are alpha-fetoprotein (AFP), human chorionic gonadotropin (HCG) and unconjugated estriol. Triple marker screening (TMS) detects 65% of Down syndrome fetuses, 60 % of trisomy 18 fetuses and many other chromosomally abnormal fetuses. This test is only a SCREEN and a positive result does not mean the fetus has an abnormality. A high rate of false positives is allowed in order to detect a high percentage of abnormals. All pregnancies that screen positive undergo further definitive testing to determine the true status of the fetus.

Amniocentesis involves inserting a needle into the uterus and withdrawing a sample of the amniotic fluid that surrounds the fetus. The placement of the needle is carefully watched by ultrasound monitoring. The fluid contains cells and many biochemicals produced by the fetus. Many tests may be performed on the amniotic fluid or fetal cells to allow the mother and physician to manage the pregnancy or prepare for the birth of an infant who may have an abnormality. A frequent laboratory test performed on the cells is chromosome analysis to detect genetic imbalances that may produce mental retardation and/or abnormal development in the fetus. This test involves growing the cells in cultures and examining the chromosomes. An example of an imbalance of genetic material is found in Down Syndrome. Down Syndrome results when there is an extra copy of chromosome number 21.

Amniocentesis is offered most frequently to pregnant women as they age since the rate of chromosome abnormalities in live born infants increases significantly for mothers beyond 33-35 years old. A mother giving birth at age 45-50 has a one in ten risk of having a chromosomally abnormal infant. For mothers of all ages, Down Syndrome affects one in each seven hundred live born infants. Other chromosome abnormalities, such as trisomy 13, trisomy 18 and the abnormalities involving the sex chromosomes may also be detected by chromosome analysis.

Another laboratory test often performed on amniotic fluid specimens is for the presence of acetylcholinesterase (ACHE) to detect openings of the central nervous system. Spina bifida or anencephaly involves openings to the spinal cord or brain. This laboratory test will detect approximately 95% of affected fetuses with outside openings to the central nervous system.

Blood Transfusion

A blood transfusion is the transfer of blood or blood products from one person (donor) into another person's bloodstream (recipient). In most situations this is done as a life saving maneuver to replace blood cells or blood products lost through severe bleeding. The following material is provided to all patients and/or their family members regarding blood transfusions and the use of blood products. Although in most situations the likelihood of a blood transfusion associated with surgery is uncommon, at times patients may require blood products. You are encouraged to discuss your particular risk of transfusion with your doctor. Your options may be limited by time and health factors, so it is important to begin making your decision as soon as possible. For example, if friends or family members are donating blood for a patient (directed donors), their blood should be drawn at least five working days prior to the anticipated need to allow adequate time for testing and labeling. You are also encouraged to check with your insurance company for their reimbursement policy.

The safest blood product is your own, so if a transfusion is likely, this is your lowest risk choice.

Pre-operative donation - donating your own blood before surgery. The blood bank draws your blood and stores it until you need it during or after surgery. This option is only for non-emergency (elective) surgery. It has the advantage of eliminating or minimizing the need for someone else's blood during and after surgery. The disadvantage is that it requires advanced planning with the donor center and your physician, which may delay surgery. Some medical conditions may prevent the pre-operative donation of blood products.

Intra-Operative or Post-Operative Autologous Transfusion - recycling your blood during or after surgery. Blood lost during surgery is filtered, and put back into your body during surgery. This can be done in emergency and elective surgeries. It has the advantage of eliminating or minimizing the need for someone else's blood during surgery. Large amounts of blood can be recycled. This process cannot be used if cancer or infection is present.

All donor blood is tested for safety making its risks very small, but no screening program is perfect and risks, such as contraction of the hepatitis virus, still exist.

Volunteer blood - blood collected from the community blood supply (blood banks). This has the advantage of being readily available, and can be life-saving when your own blood is not available. The disadvantage is that there is a risk of disease transmission and allergic reactions.

Directed donor blood - blood is collected from the donors you select. You must select people with your own blood type who you feel are safe donors. Like volunteer blood, there is still a risk of disease transmission, such as hepatitis and AIDS, and allergic reactions. This process requires the blood be donated 5 days in advance of the procedure, and requires a physician's order. It may not necessarily be safer than volunteer donor blood.

Blood Transfusion At A Glance

• Transfusion of your own blood (autologous) is the safest method but requires planning ahead and not all patients are eligible.
• Directed donor blood allows the patient to receive blood from known donors.
• Volunteer donor blood is usually readily available and when properly tested has a low incidence of adverse events.
• Blood conserving techniques are an important aspect of limiting transfusion requirements.

What is CA 125 and what does it tell my physician?

CA 125 is a protein made by certain cells in the body which include those of the uterine tubes, uterus, cervix, and the lining of the abdominal and chest cavities (peritoneum and pleura). Its function is not currently understood. CA stands for cancer antigen. CA 125 is usually measured from a blood sample.

It is not possible to interpret the meaning of an abnormally high CA 125 without additional information about the particular patient being evaluated. The reason is that this test result can be increased in many different benign and malignant conditions. The two most frequent situations in which CA 125 is used is to monitor patients with a known malignancy or as one of several tests in the workup of a patient suspected of having a tumor.

In the patient who is known to have a malignancy, such as ovarian carcinoma, the CA 125 level can be monitored periodically. A decreasing level indicates effective therapy while an increasing level indicates tumor recurrence. Because of test variation small changes are usually not considered significant. A doubling or halving of the previous value would be important.

In the patient who is being evaluated for a pelvic mass, an elevated CA 125 level is associated with malignancy in approximately 90% of cases. However, without a demonstrable mass, the association is much weaker.

There are several benign conditions which can elevate CA 125 include infections of the lining of the abdomen and chest (peritonitis and pleuritis), menstruation, pregnancy, endometriosis, and liver disease. Benign tumors of the ovaries can also cause an abnormal test result. Increases can also be seen in malignancies of the uterine tubes, endometrium, lung, breast, and gastrointestinal tract.

What is the Prostate Specific Antigen?

The prostate specific antigen (PSA) is a substance produced by certain cells in the prostate gland. PSA is a protein and is a part of semen that causes it to liquefy (keeps the semen watery). Most of the PSA produced by the prostate gland is carried out of the body in semen, but a very small amount escapes into the blood stream.

PSA is tested in the blood. Since the amount of PSA in the blood is very low, detection of it requires a very sensitive type of technology (monoclonal antibody technique).

The PSA protein can exist in the blood by itself, or it can join with other substances in the blood. When it is by itself, it is known as free PSA. When it is joined with other substances, it is known as bound or complexed PSA. Total PSA is the sum of free and bound forms. This is what is measured as the standard PSA test.

The PSA test is used in two distinctly different ways with respect to detecting prostate cancer. It can be used in men who are not known to have the disease (screening or diagnostic test) and those who are known to have the disease (tumor marker or monitoring test).

As a screening or diagnostic test, an abnormal result will usually require additional testing. As a tumor marker or monitoring test, an abnormal result indicates recurrence of prostate cancer following initial therapy. For example, if the prostate gland is surgically removed (prostatectomy), and all of the cancer is contained within the gland, then the PSA should drop to zero. If on subsequent testing the PSA test is positive and shows increasing levels, then not all of the cancer was successfully removed and it has spread.

Other diseases that affect the prostate gland can cause an elevated PSA. The most frequent problem is known as benign prostatic hypertrophy (enlargement) or hyperplasia (BPH). This condition is due to an increase in the size of the prostate gland that typically occurs with aging. Infection of the prostate gland (prostatitis) is another relatively common affliction that can also cause an abnormal elevation of PSA. Other conditions include poor blood supply to the prostate gland, instrumentation of the urethra (drainage tube from the bladder), urinary retention, and prostate biopsy.

Most of the PSA protein released into the blood becomes attached to other blood proteins. The PSA that does not become attached is known as free PSA and can be measured. It has been found that the level of free PSA is decreased in men who have prostate cancer compared to those with benign conditions. This test is used most frequently when using a PSA for screening, to confirm a borderline result.

A few percent of prostate cancers do not produce detectable increases in the blood PSA, even with advanced disease. Many early cancers will also not produce enough PSA to cause a significantly abnormal blood level. It is therefore important not to rely only on blood PSA testing. The most useful additional test is a physical prostate examination by a doctor known as the digital rectal exam (DRE). During this examination a doctor inserts a finger into the rectum to feel the prostate for lumps, size, shape, tenderness, and hardness.