Diagnosis of Juvenile Rheumatoid Arthritis
Tests and diagnosis discussion for Juvenile Rheumatoid Arthritis:
Doctors usually suspect JRA, along with several other
possible conditions, when they see children with persistent joint pain
or swelling, unexplained skin rashes and fever, or swelling of lymph
nodes or inflammation of internal organs. A diagnosis of JRA also is
considered in children with an unexplained limp or excessive
No one test can be used to diagnose JRA. A doctor
diagnoses JRA by carefully examining the patient and considering the
patient's medical history, the results of laboratory tests, and x rays
that help rule out other conditions.
- Symptoms--One important consideration in diagnosing JRA is
the length of time that symptoms have been present. Joint swelling or
pain must last for at least 6 weeks for the doctor to consider a
diagnosis of JRA. Because this factor is so important, it may be
useful to keep a record of the symptoms, when they first appeared, and
when they are worse or better.
- Laboratory tests--Laboratory tests, usually blood tests,
cannot by themselves provide the doctor with a clear diagnosis. But
these tests can be used to help rule out other conditions and to help
classify the type of JRA that a patient has. Blood may be taken to
test for RF and ANA, and to determine the erythrocyte sedimentation
- ANA is found in the blood more often than RF, and both are found
in only a small portion of JRA patients. The RF test helps the
doctor tell the difference among the three types of JRA.
- ESR is a test that measures how quickly red blood cells fall to
the bottom of a test tube. Some people with rheumatic disease have
an elevated ESR or "sed rate" (cells fall quickly to the bottom of
the test tube), showing that there is inflammation in the body. Not
all children with active joint inflammation have an elevated ESR.
- X rays--X rays are needed if the doctor suspects injury to
the bone or unusual bone development. Early in the disease, some x
rays can show cartilage damage. In general, x rays are more useful
later in the disease, when bones may be affected.
- Other diseases--Because there are many causes of joint pain
and swelling, the doctor must rule out other conditions before
diagnosing JRA. These include physical injury, bacterial or viral
infection, Lyme disease, inflammatory bowel disease, lupus,
dermatomyositis, and some forms of cancer. The doctor may use
additional laboratory tests to help rule out these and other possible
(Source: excerpt from Questions and Answers About Juvenile Rheumatoid Arthritis: NIAMS