There's no specific test available to diagnose Kawasaki disease. Diagnosis largely is a process of ruling out diseases that cause similar signs and symptoms, including:

  • Scarlet fever, which is caused by streptococcal bacteria and results in fever, rash, chills and sore throat
  • Juvenile rheumatoid arthritis
  • Stevens-Johnson syndrome, a disorder of the mucous membranes
  • Toxic shock syndrome
  • Measles
  • Certain tick-borne illnesses, such as Rocky Mountain spotted fever

The doctor will do a physical examination and have your child take other tests to help in the diagnosis. These tests may include:

  • Urine tests. These tests help rule out other diseases.
  • Blood tests. Besides helping to rule out other diseases, blood tests look at white blood cell count, which is likely to be elevated, and the presence of anemia and inflammation, indications of Kawasaki disease.

    Testing for a substance called B-type natriuretic peptide (BNP) that's released when the heart is under stress may be helpful in diagnosing Kawasaki disease earlier, recent research found. But, more research is needed to confirm this finding.

  • Electrocardiogram. This test uses electrodes attached to the skin to measure the electrical impulses of your child's heartbeat. Kawasaki disease can cause heart rhythm complications.
  • Echocardiogram. This test uses ultrasound images to show how well the heart is functioning and can help identify coronary artery abnormalities, if present.