Diagnosing Arthritis and Other Rheumatic Diseases in Children

Diagnosing pediatric arthritis and other rheumatic diseases is often difficult, as many symptoms are similar among the different diseases. To make an accurate diagnosis, your child's doctor may need to conduct the following:

• Medical history

• Physical examination

• Laboratory tests, X-rays, and other imaging tests

• Imaging tests

When reviewing your child's medical history, your doctor may ask the following questions about your child:

• Where is the pain?

• How long has your child experienced the pain?

• When does the pain occur and how long does it typically last?

• When did you first notice your child's pain?

• What was your child doing when he or she first noticed the pain?

• How intense is the pain?

• What tends to relieve the pain?

• Has your child had any illnesses or injuries that may explain the pain?

• Is there a family history of arthritis or other rheumatic diseases?

• What medication(s) is your child currently taking?

The following is a list of common laboratory tests used for the diagnosis of pediatric arthritis and other rheumatic diseases, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases:

• Antinuclear antibody (ANA). This measures blood levels of antibodies, which are often present in people with rheumatic disease.

• Arthrocentesis (also called joint aspiration). A procedure that involves obtaining a sample of synovial fluid in the joint for examination by inserting a thin, hollow needle into the joint and removing the fluid with a syringe.

• Complement. A blood test that measures the level of complement, a group of proteins in the blood. Low levels of complement in the blood are associated with immune disorders.

• Complete blood count (CBC). A measurement of size, number, and maturity of different blood cells in a specific volume of blood.

• Creatinine. A blood test to evaluate for underlying kidney disease.

• Erythrocyte sedimentation rate (ESR or sed rate). A measurement of how quickly red blood cells fall to the bottom of a test tube. When swelling and inflammation are present, the blood's proteins clump together and become heavier than normal. Thus, when measured, they fall and settle faster at the bottom of the test tube. Generally, the faster the blood cells fall, the more severe the inflammation.

• Hematocrit (PCV, packed cell volume). This measures the number of red blood cells present in a sample of blood. Low levels of red blood cells (anemia) are common in people with inflammatory arthritis and rheumatic diseases.

• Rheumatoid factor (RF). This detects whether rheumatoid factor is present in the blood (an antibody found in the blood of most, but not all, people who have rheumatoid arthritis, as well as other rheumatic diseases).

• Urinalysis. Testing of a urine sample for protein, red blood cells, white blood cells, or casts to indicate kidney disease associated with several rheumatic diseases.

• White blood cell count (WBC). This measures the number of white blood cells in the blood. Increased levels of white blood cells may indicate an infection, while decreased levels may indicate certain rheumatic diseases or reaction to medication.

• C-reactive protein (CRP). A protein that is elevated when inflammation is found in the body. Although ESR and CRP reflect similar degrees of inflammation, sometimes one will be elevated when the other is not. This test may be repeated to test your child's response to medication.

Imaging techniques may give your child's doctor a clearer picture of what is happening to your child's joint(s). Imaging techniques may include:

• X-ray. A diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film (Arthrography is a specific X-ray of the joint).

• Computed tomography scan (also called a CT or CAT scan). A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce horizontal, or axial, images (often called slices) of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general X-rays.

• Magnetic resonance imaging (MRI). A diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

• Arthroscopy. The use of an intra-articular camera inserted into the joint through a small incision to show the inside of a joint. The procedure allows the doctor to also assess, repair, or reconstruct various tissues both within and around joints.

• Joint ultrasound. A diagnostic procedure used occasionally to find inflammation before X-rays show damage.

• Bone densitometry (DEXA). An imaging study to measure bone density; used primarily to detect osteoporosis.

Measurement of pain may help your child's doctor find a diagnosis and determine appropriate treatment. The measurement, or assessment, of pain may be difficult in younger children and infants, due to their inability to verbalize qualities such as location, duration, or intensity of pain, as well as factors which may cause pain. Your observations of your very young child or infant will be helpful in aiding the doctor's pain assessment.

You or your child (if he or she is of an appropriate age to participate) may be asked to describe the pain on a scale of one to 10 and/or using certain descriptive words. Other pain scales use pictures of faces that are smiling and gradually change to an expression of extreme pain and the child points to the face that he or she thinks best matches his or her own pain. The child's age and stage of development, as well as factors such as culture, earlier pain experiences, the child's temperament, and even your response to your child's pain are considered.