Laboratory Tests in Juvenile Scleroderma
In general, laboratory tests do not make any diagnosis. This is particularly true for scleroderma. This statement may come as a shock to many of you. But it is true.
Written By Balu H. Athreya, M.D.
duPont Hospital for Children
Laboratory test cannot differentiate a sick person from a normal person. A constellation of symptoms and signs and a careful physical examination by a well-trained physician suggests that there is some disease process responsible for the signs and symptoms. The laboratory tests then help confirm or exclude each of the diagnosis in the physician’s list of differential diagnosis.
Scleroderma is primarily a clinical diagnosis. In other words, it is a diagnosis based on the history and physical examination. Skin biopsy is done to confirm the diagnosis and to exclude a few conditions that may mimic. Then, why do physicians ask for so many tests?
Physicians use laboratory tests for several purposes. Confirming the clinical diagnosis is one of them. As mentioned already, skin biopsy is the one real requirement in scleroderma – and even that is not needed every time. Other reasons to obtain laboratory tests are to give prognosis (tell the family what to expect), to assess response to treatment, to monitor for adverse effects of medications and to monitor involvement of specific organs.
Localized scleroderma (Lo Scl) may be called by several names including morphea, linear scleroderma and coupe de sabre. Some of the tests that may be obtained in patients with Lo Scl are: Complete blood count (CBC), urinalysis, immunoglobulins, Antinuclear antibody (ANA or FANA), Rheumatoid Factor (RF), anitbody to single stranded DNA (ssDNA) and soluble interleukin 2 receptor level (sIL 2 r).
CBC is done routinely to look for anemia or other unexpected abnormalities. It is also done as a baseline before starting any medicines. CBC includes hemoglobin which is a measure of anemia (non-medical people may call it low iron in the body); white blood cells which are part of our immune system and are important in the body’s defense against infections; and platelets which are important to help clotting of blood when there is an injury. Usually CBC is normal in children with Lo Scl is an increase in the numbers of one of the white cells called the eosinophil.
Urinalysis is also done routinely and is expected to be normal. This is also a test that will be repeated during treatment with medicines such as penicillamine to monitor for any unwanted and unexpected damage to the kidneys.
Other tests may be done in Lo Scl are: immunogloblins (Ig), rheumatoid factor (RF), Antinuclear antibody (ANA), antibody to single stranded DNA (anti ssDNA) and soluble interleukin 2 receptor (sIL 2r). Immunoglobulins are proteins in our blood that carry all the protective anitbodies against infections. All of us have these in circulation. These may be increased in some patients with Lo Scl. RF is also a type of protein not normally present in circulation. It is a combination of different types of immunoglobulins. Some children with Lo Scl may show this abnormal protein in their blood. ANA is an antibody to our cell nucleus and is not normally present in circulation; if present it is in very small amounts. In some patients with Lo Scl this may be increased. Antibody to ssDNA is also not normally present in circulation. When it is present some physicians use this protein to monitor progress of the disease. Another protein that may be elevated in patients with Lo Scl is sIL2r and if elevated may be useful to monitor progress and response to therapy.
Systemic Sclerosis (SSc) this variety of scleroderma has two sub-types. One is called the Diffuse cutaneous type (dc SSc) and the other is the limited cutaneous type (lc SSc). Both are less common among children compared to adults. The limited variety is particularly rare in its complete form although it probably starts in childhood and adolescent age in many patients. A special type of antibody called the anit-scleroderma 70 (also called anti-topoisomerase I) antibody is associated with and specific for the dc SSc. Another type of antibody called the anti-centromere (also called anti-kinetochore) antibody is associated with the lc SSc. Therefore, when your physician suspects the systemic variety of scleroderma, he/she may order these antibody tests. Here is one exception to the statement I made earlier about laboratory tests. In the systemic variety, these tests are of great importance to classify and also predict what to expect in the course of the disease.
Both these types of SSc involve not only the skin but also several internal organs. The dc SSc is often associated with involvement of the gut and the kidney. The lc SSc is often associated with lung disease. Therefore, in addition to the routine tests listed earlier such as CBC, urinalysis, Ig, ANA and RF, your physician may order tests to look for involvement of internal organs depending on the sub-type and symptoms. Special breathing tests (pulmonary function tests (PFT) and X-ray of the chest called HRCT helps looks for special type of involvement of the lung in scleroderma. In some situations, the physicians may pass a tube down the air-passage and collect cells. This is called BAL (broncho-alveolar lavage) and this may be helpful to decide how much inflammation there is in the lungs and what treatment to give.
Electrocardiogram is useful to look for changes in the rhythm of the heart. Echocardiogram helps look for changes in the function of the heart valves and heart muscle. Blood tests (BUN and creatinine) and blood pressure measurements are useful to look for kidney disease.
A special type of ballon is passed down the gullet (esophagus) to measure the movement of the food passage and also to look at the valve (sphincter) at the junction between the gullet and the stomach. This is called the esophageal manometry. In SSc this may show evidence for poor movement of the gullet and the poor tone to the sphincter. You may already know that this is the reason for difficulty in swallowing and the heart-burn which patients with SSc experience. Special barium X-rays may be needed to look at the lower bowel.
Finally a simple test called nail-fold capillaroscopy often helps look for damage to small vessels in the body called capillaries. In this test the physician looks at the edge of the nails with a special microscope. Changes in the type, number and shape of capillaries in this location give a simple way of knowing the changes taking place in capillaries in the internal organs.
Laboratory tests have advanced our understanding of many of the diseases, but they have their limitations. These tests have to be interpreted in relation to the signs and symptoms of individual patients and with a full understanding of the limitations of the tests. This is what the specialist physicians are trained to do. But these tests alone do not ensure quality of care. Good communication and trusting relationship between members of the patient care team consisting of the patient (child), the family, the primary physician and the specialist are essential for assuring good qualilty of care.
Please keep in mind, this webpage is for your information only.
Please check with your child's physician for any treatments.
For more information on Juvenile Scleroderma, contact:
Juvenile Scleroderma Network, Inc.
1204 W. 13th Street, San Pedro, CA 90731
Tel: (310)519-9511 (Pacific Time)
24 Hour Support Line: 1-866-338-5892 (toll-free)
Speak to another JSD parent for emotional and logistical support
provided by home-based JSD volunteers. For medical advice, please
contact your child's physician.
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