Home Topics ...Symptoms And Diagnosis

Lupus: Diagnosing Through Symptoms and Tests

Diagnosing lupus is difficult because the symptoms can be similar to those of several other illnesses. Because of this, the American College of Rheumatology has developed a number of criteria to help diagnose lupus.

Common Symptoms of Lupus

The criteria for diagnosing lupus includes a list of symptoms associated with the condition. The comprehensive nature of sysmptoms reflects how lupus afflicts the body as a whole. According to the American College of Rheumatology, eleven signs and symptoms are used to help distinguish lupus from other medical conditions. Four of these symptoms must occur or have occurred at one time for a positive lupus diagnosis.

The following are the eleven criteria for determining the presence of lupus:

"butterfly" rash on the nose and cheeks
discoid rash—small, coin-shaped, red, flaky rashes
light sensitivity
oral ulcers
joint pain and/or swelling
serositis—an inflammation of the serous lining of the heart and lungs
kidney damage
neurological symptoms
erratic blood cells, including decreased numbers of red, white or platelet cells
the presence of anti-nuclear antibodies in an ANA blood test
the presence of immunological disorders.

In addition to the above symptoms, people with lupus may experience:

sore joints
fever over 100 °F
weight loss
nausea
vomiting
extreme fatigue.

To learn more about the common lupus symptoms, see the list of links to the left.

Diagnostic Test for Lupus

The diagnosing physician may order a number of tests to help with the diagnostic process:

ANA Blood Test: Although no single test can determine the presence of lupus, the most widely used test is the immunofluorescent anti-nuclear antibody test, or ANA blood test. The ANA blood test is a blood test that measures autoantibodies known as anti-nuclear antibodies. These autoantibodies target the body's cellular nuclei—a response not normally carried out by the immune system. A normal immune system creates antibodies to fight bacteria, viruses and other foreign substances that enter the cell. Autoantibodies mistake normal, healthy cells for invaders and attack them.

Although approximately 95 percent of people with lupus have a positive ANA blood test, the ANA blood test can be positive in individuals who have other connective tissue diseases, autoimmune diseases or are being treated with certain prescription medications. A negative ANA blood test is a likely sign that an individual does not have lupus. That is why the ANA blood test is evaluated in conjunction with other diagnostic tests and a review of a person's medical history.

Evaluation of Kidney Function: Abnormal kidney function also serves as a good indication that a person suffers from lupus. Tests that check the normalcy of kidneys therefore provide good alternatives and supplements to ANA blood tests. The following are ways to test kidney health:

A complete blood count can determine whether the white cell, red cell and platelet cell numbers are within normal ranges. Blood tests also measure creatinine levels. Increased creatinine levels can signal a loss of kidney function, which may occur if lupus has affected the kidneys.
A urinalysis can determine whether proteins are leaking into the urine. Proteins are not present in the urine if the kidneys are functioning normally.
If blood tests and urinalysis are positive for impaired kidney function, then further tests, including a kidney biopsy, are necessary to determine the extent of kidney failure at the cellular level.

Visual Imaging Tests: Fever, chest pain or shortness of breath can signal the presence of serositis or Pericarditis, other possible symptoms of lupus. Serositis and Pericarditis refer to inflammations of the serous connective tissue: serositis affects the lungs, heart and abdomen while pericarditis affects only the outer surface of the heart. Visual imaging tests like x-rays or CAT scans can help diagnose the presence of serositis or pericarditis that may, in turn, lead to a diagnosis of lupus.

Resources

Beers, M.H. & Berkow, R. (ed). Diffuse connective tissue disease. The Merck Manual of Diagnosis and Therapy, 17th Edition. Merck Research Laboratories, NJ, 1999.

Fauci, A., Braunwald, E., Isselbacher, K., Wilson, J., Martin, J., Kasper, D., Hauser, S. & Longo, D. (ed). Harrison's Principles of Internal Medicine, 14th Edition. McGraw-Hill, NY, 1998.

Louis, P.J. & Fernandes, R. (2001). Review of systemic lupus erythematosus. Oral Surgery Oral Medicine Oral Pathology 91, 512-516.

Lupus Foundation of America. (2003). Facts and overview