The diagnosis of Kawasaki disease is primarily clinical, based on a defined set of signs and symptoms rather than a single confirmatory test.
Doctors must rely on clear signs because there is no single test to confirm the condition. This makes it harder to spot, especially since Kawasaki disease can look like common infections in children. But early diagnosis is vital. If treatment begins within the first 10 days, it can prevent serious heart problems.
Doctors must watch closely for key symptoms and follow standard guidelines. These help identify the illness even when it doesn’t appear obvious at first.
Even though tests and scans can support the diagnosis, the most important part is careful observation. Looking at how symptoms appear and change over time helps doctors make the right call.
1. Diagnostic Criteria
Doctors around the world use a standard set of signs to diagnose Kawasaki disease. These rules come from the American Heart Association and are used in many countries.
To make the diagnosis, a child must have:
- A fever for five or more days (usually high and doesn’t go away with regular fever medicine), and
- At least four of the following five signs:
- Red eyes without pus
- Red lips, red mouth, or a “strawberry” tongue
- Swelling or redness in the hands or feet, or peeling skin later
- A rash not caused by medicine or other viruses
- A large, one-sided neck gland (over 1.5 cm)
Sometimes, a child with all the symptoms but a shorter fever can still be diagnosed. Likewise, a child with fewer than four signs may still have Kawasaki disease if other evidence supports it.
2. Incomplete or Atypical Kawasaki Disease
Not all children show the full list of symptoms. Incomplete Kawasaki disease is more common in babies under six months and older kids. Their signs might be mild or unclear.
These cases are more risky because they are often diagnosed late. This can lead to missed treatments and heart problems.
Doctors must stay alert. They may use extra tests and scans to confirm the condition and start treatment quickly.
3. Lab Tests to Support Diagnosis of Kawasaki Disease
No single blood test can confirm the disease. Still, several tests can support the diagnosis and check how much inflammation is present:
- Complete blood count (CBC): May show high white blood cells, low red blood cells, and high platelets
- CRP and ESR: These are often raised, showing body-wide inflammation
- Liver tests: May be slightly high
- Urine test: May show white blood cells without bacteria
- Low albumin: Can mean strong inflammation
- BNP or NT-proBNP: These may be high if the heart is involved
These tests are helpful, but only when used with symptoms and other findings.
4. Echocardiography
Heart ultrasound (echocardiogram) is one of the most important tools for diagnosing Kawasaki disease. It is safe and painless. It helps doctors look for:
- Swollen or stretched heart arteries
- Swelling in the heart muscle
- Extra fluid around the heart
- Valve problems like mild leaking
- Weak heart pumping
Doctors should do this scan as soon as they think the child has Kawasaki disease, even before treatment begins. Follow-up scans are done at two and six weeks to check for changes.
If the heart arteries can’t be seen clearly, other scans like CT or MRI may be used.
5. Conditions That Mimic Kawasaki Disease
Many other illnesses can look like Kawasaki disease. This makes diagnosis harder. Some of the most common lookalikes include:
- Measles
- Scarlet fever
- Viral rashes (like from adenovirus)
- Toxic shock syndrome
- Mono (from Epstein-Barr virus)
- Juvenile arthritis
Doctors take a full history and do extra tests to rule out these other problems. But if they strongly suspect Kawasaki disease, they should not wait too long for lab confirmation. Early treatment is more important, especially if the heart is already affected.
6. Specialist Help in Diagnosis of Kawasaki Disease
In unclear cases, it’s smart to call in specialists. These might include:
- Infection experts
- Rheumatologists (joint and immune doctors)
- Heart doctors (cardiologists)
Referral is especially helpful when:
- The diagnosis isn’t clear
- The symptoms are unusual or don’t fit the usual pattern
- The child is under 6 months or over 5 years
- Heart problems are already seen
In some hospitals, a team of doctors works together to spot and treat Kawasaki disease early.
7. New Tests and Research
Scientists are working to find better ways to diagnose Kawasaki disease faster. Some new blood tests may help tell it apart from other illnesses. These include:
- Calprotectin
- LRG1
- Procalcitonin
- Cytokine tests
These tests are still being studied and not used everywhere yet. In the future, they may help doctors find high-risk kids sooner.
Researchers are also studying genes. This may lead to tools that predict which kids might get the disease before symptoms even begin.
8. Why Early Diagnosis Matters
Time is critical. Giving IVIG within the first 10 days lowers the chance of heart artery problems. The sooner treatment begins, the better the outcome.
Late or missed diagnoses—especially in incomplete cases—cause most of the severe heart issues. That’s why doctors should always consider Kawasaki disease if the symptoms fit, and act quickly when needed.
Final Thoughts
The diagnosis of Kawasaki disease takes close attention to symptoms, blood test results, and heart scans.
There is no single test to confirm it. That’s why quick thinking and experience matter so much. Delays in treatment can cause lasting heart damage. But with early care, most kids recover fully.
As new tools are developed, diagnosing Kawasaki disease may get easier. Until then, doctors must rely on trusted signs, careful checks, and a clear understanding of how the disease shows up in different children.
