Chaim M. Brickman MD, Director, & Teresa H. Doyle, MSN, RN C.
Lupus Program of Sinai Hospital, Detroit, Michigan, U.S.A. ( Thanks to Lupus Cope USA, March 1990 )
"What do my blood and urine tests tell me about my lupus ?"
Someone asks us this question nearly every day, and we're always glad to answer. We believe that contributes to your health and wellbeing when you understand the basics about your illness and your laboratory tests. This article will discuss some of the tests commonly used in the diagnosis and treatment of lupus.
Lupus and the Process of Inflammation
The immune system is designed to protect the body from harmful invaders such as bacteria, viruses and other "foreign" matter. It does this through a process called inflammation in which the body destroys foreign matter which doesn't belong. We can often tell that there is inflammation in some parts of the body. For example, an inflamed joint readily shows the "cardinal signs" of inflammation : warmth, redness, swelling and pain that make it difficult to use that body area. Inflammation in another body part such as the kidney may cause few, if any, of these signs early in the inflammation process. An experienced physician using the correct methods - history and physical exam, x-ray, lab tests and others - is able to detect, and treat this type of inflammation.
Lupus is an inflammatory condition in which the immune system loses its ability to tell the difference between foreign, harmful invaders from the outside and "self" ( things that belong in the body ). As a result of this confusion, the lupus patient's immune system attacks its own tissues causing widespread inflammation. Unfortunately, doctors do not have all the answers needed for the cure and prevention of lupus. However, we can identify lupus earlier than ever before, thereby preventing many of its ill effects. Proper use of diagnostic tests - especially selected tests of the blood and urine - makes it possible to monitor the disease and its treatment more effectively than ever before.
The Complete Blood Count ( CBC ) and Differential
Blood consists of two elements which may be tested by your physician :
Platelets - Part of the complex mechanism for clotting blood, these cells may increase in numbers when there is active inflammation. Low platelet counts are occasionally seen in lupus and could lead to unusual bleeding episodes.
White Blood Cells ( WBC ) - The doctor can request a differential, a count of the various kinds of WBC. Among others they include:
Antinuclear Antibody ( ANA )
This phrase literally means "substance against the cell nucleus". Since the nucleus is the "headquarters" of the living cell, the ANA can actually damage or even destroy cells and tissues. ANA reports include a number ( or titer ) and a pattern. The titer tells us how many times the technician had to mix fluid from the patient's blood to get a sample free of ANA's. Thus, a titer of 1:640 shows a greater concentration of ANA than 1:320 or 1:160, since it took 640 dilutions of the plasma before the ANA was no longer detected. The apparent great difference between various titers can be misleading. Since each dilution involves doubling the amount of test fluid, it is not surprising that titers can increase rather rapidly. In actuality, the difference between a 1:160 titer and a 1:320 titer is but a single dilution. This does NOT necessarily represent a major difference in disease activity. ANA titers go up and down during the course of the disease, therefore it is not always possible to tell from the titer the severity of a person's lupus. A titer below 1:160 is usually considered "negative" or not present.
The ANA pattern is studied by microscope. The technician examines a specially-prepared slide that shows where antibodies attack the nucleus. Certain antibodies attack certain areas of the nucleus, producing four specific patterns. The rim ( peripheral ) pattern is the most specific pattern for lupus while the homogeneous ( diffuse ) pattern is the most common pattern seen. The remaining patterns are the speckled and the nucleolar patterns. In some cases the pattern helps the doctor decide which of the autoimmune diseases is causing the problem and which treatment program is appropriate.
VDRL
Sometimes the antibodies produced in lupus interact with chemicals used to test for other diseases. One test for syphilis, the VDRL, sometimes becomes falsely positive for this reason. In this case, the VDRL does not mean that the person has syphilis ; instead it aids in diagnosing lupus. Just to make sure, another more specific syphilis test is used to confirm the doctor's suspicions.
Complement
The blood also contains proteins known as complement proteins, used by the immune system as "ammunition" for destroying the cellist has identified as "enemies". When inflammation is very active the complement is used up, resulting in lower blood levels. Determination of complement levels therefore helps the doctor to evaluate the intensity of the inflammation. Complement proteins are identified by the letter "C"; and a number. The most frequently studies complement tests are C3, C4, and CH50.
Urine tests
Urinalysis, the urine test most commonly requested, enables the doctor to evaluate the effects of infection, lupus or medications on the kidneys.
The job of the kidneys is to rid the body of unneeded waste material. If the kidney becomes inflamed, it may become ineffective. RBC's, WBC's and proteins such as albumin may pass through the filtering system into the urine ; or they may stay in the kidney for a while before being released as "casts" of certain kidney areas. If a urinary tract infection is suspected the physician may request a culture and sensitivity in order to help decide which antibiotic would be most effective.
If considerable protein is found in the urine, the doctor will order a 24-hour collection to determine how much is being lost in one day. At the same time a creatinine clearance is done to determine how well the kidney is working.
Biopsy
The biopsy is one of the best ways to evaluate an organ or tissue. The procedure involves removal of a small sliver of tissue, followed by examination under the microscope. The biopsy enables the doctor to identify the amount of inflammation and damage to the tissue. Furthermore, tests can be performed on the specimen in order to determine whether the problem is due to lupus or due to some other factor such as infection, medication etc. Just about any tissue can be biopsies, the most common sites biopsied are skin and kidney.
Anti-Phospholipid/Anti-Cardiolipin Antibodies
Approximately 30-50% of lupus patients have antibodies in their blood directed against certain chemicals in their body known as phospholipids. One type of phospholipid is called cardiolipid because it is found in many tissues including heart ( cardiac ) tissue. Patients with these antibodies may have abnormal laboratory tests for clotting ( called PT and PTT tests ). Some patients with these antibodies may develop clotting problems, problems with recurrent loss of pregnancies, false positive VDRL tests ( see VDRL above ) or heart valve problems.
In Conclusion
We are often asked why many of the above tests are performed even when the patient feels fine.
Experience has shown that lupus activity is often not recognised by the patient : the laboratory tests can warn of problems that are unfelt or are still rather small. Since most patients with lupus take medications, the doctor must monitor the effects of these medications by means of specific blood tests.
Finally, laboratory testing has an important role in the detection, treatment and monitoring of the lupus and related conditions. However, it is not the only available technique. Laboratory data supplements other information obtained via the medical history, the physical examination and other diagnostic tests. If you do not understand the meaning of any of your laboratory tests, ask your doctor. A well-informed patient is better able to make good health decisions and to co-operate in a safe health-enhancing treatment program.
Disclaimer :
The Lupus Group of W.A. (Inc.) does not recommend or endorse any products, drugs, treatments, procedures, medical or health professional in this article. We suggest you discuss this information with your doctor or specialist.