Systemic Lupus Erythematosus (SLE) | Testing and Diagnosis

How is lupus diagnosed?

You may have read that lupus is extremely difficult to diagnose, and that some patients go a long time, even years, before they know what’s wrong with them. And it’s true the symptoms of lupus can mimic many other illnesses, such as infection and cancer. But if you bring your child to a pediatric rheumatologist — the kind of doctor who knows best what this disease looks like in children — odds are that he or she can determine whether it’s lupus relatively quickly, and if treatment is needed, it can begin right away.

Since there is no single symptom or test result that points to lupus, your child’s doctor will collect a lot of information to make a diagnosis. He or she will conduct a thorough physical exam, make a list of your child’s current symptoms and talk with you about your child’s medical history and the medical history of close family members.

Your child’s doctor will also use certain lab tests to help make a diagnosis and, later, to keep tabs on how the lupus is progressing. These tests include:

  • complete blood count (CBC), which is a collection of tests measuring the size, number and maturity of different blood cells in a specific amount of blood. Two important tests are:
    • white blood cell count (WBC):- the number of white blood cells present. Low levels may point to an active problem with the immune system, like lupus. High levels, on the other hand, may indicate an infection.
    • hematocrit : the number of red blood cells present. Anemia, or low levels of red blood cells, is often a symptom of lupus.
  • antinuclear antibody(ANA), which detects certain abnormal proteins, called antinuclear antibodies, that the immune system often makes when attacking the body’s own tissues. The presence of these antibodies is common in lupus and other autoimmune diseases. However, testing positive for ANA does not equal lupus. Positive tests are also seen in children with other conditions, and even in a handful of perfectly healthy children.
  • anti-DNA, which detects a specific antinuclear autoantibody commonly seen with lupus nephritis.
  • complement (C3 and C4), which measure blood complement levels. The complement system includes a group of proteins that are part of the immune system. Low levels of complement may indicate lupus activity, and increase the risk for infection.
  • C-reactive protein (CRP), which measures the amount of a protein made in the liver. CRP levels tend to increase when there’s an inflammatory process. CRP levels rise very quickly, and may indicate lupus activity or may reflect a new infectious process somewhere in the body.
  • erythrocyte sedimentation rate (ESR or sed rate), which measures how quickly red blood cells fall to the bottom of a test tube. If the cells to clump together and fall more rapidly than normal, it can signal there is inflammation in the body.

Your child’s doctor may order other lab tests or imaging tests to check for signs of lupus in specific organs. A urinalysis, for example, can help show whether lupus is affecting the kidneys, while a chest x-ray may show telltale inflammation around the heart or lungs.

Sometimes a biopsy can be helpful in making a diagnosis or evaluating the health of a specific organ or tissue. Almost any part of the body can be biopsied—in which a small sliver of tissue is removed and examined under a microscope— although in lupus it tends to be the skin or the kidneys.

The 11 criteria for lupus

Since lupus symptoms vary so widely and test results don’t always tell the full story, you may wonder how doctors are able to put the puzzle pieces together to come up with a diagnosis. Much of it depends on their past experience with patients, but they also bear in mind 11 lupus criteria laid out by the American College of Rheumatology.

Typically, at least four of the following things must be present for a doctor to diagnose lupus:

  • malar rash— a butterfly-shaped rash across cheeks and nose
  • discoid rash— raised, scaly patches on the skin
  • photosensitivity— skin rash caused by sun exposure
  • oral ulcers— small, usually painless sores in the mouth
  • arthritis — swelling and achiness in at least two joints
  • cardiopulmonary problems — inflammation around the heart and/or lungs
  • neurological problems — such as seizures and/or psychosis
  • kidney problems — such as blood in the urine
  • hematologic (blood) problems— low levels of red blood cells (anemia), white blood cells or platelets
  • positive antinuclear antibody (ANA) test
  • other positive blood tests that may indicate an autoimmune disease

It’s not unusual, though, for experienced physicians to make a diagnosis even when fewer than four criteria are present.

When to seek medical advice

If your child has symptoms such as fever, fatigue, joint stiffness and skin rashes — especially a butterfly-shaped rash across her cheeks and nose — it might mean she has lupus. You should make an appointment with your child’s pediatrician, who will then make a referral to a rheumatologist if lupus is suspected.

If your child has already been diagnosed with lupus, you should call her specialist about any sudden changes in her symptoms or the appearance of new ones. And remember that infections can potentially be more serious in children with lupus: If your child develops a fever or feels increasingly unwell, let her doctor know right away.