What is the diagnostic workup for Kawasaki disease?

From the Guidelines

The workup for Kawasaki disease involves a comprehensive clinical evaluation and laboratory testing, with a focus on early diagnosis and treatment to reduce the risk of coronary artery aneurysms, as evidenced by the most recent guidelines 1. The diagnosis of Kawasaki disease is primarily clinical, based on the presence of fever for at least 5 days plus at least four of five principal clinical criteria: bilateral conjunctival injection, oral mucosal changes, peripheral extremity changes, polymorphous rash, and cervical lymphadenopathy. Initial assessment includes:

• A complete blood count showing leukocytosis with neutrophilia
• Elevated erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)
• Liver function tests revealing elevated transaminases
• Urinalysis that may show sterile pyuria
• A platelet count which is often elevated in the second week of illness Echocardiography is essential to evaluate for coronary artery abnormalities, which are the most serious complications. Additional tests include:
• Serum albumin (often decreased)
• Electrolytes to check for hyponatremia
• Sometimes lumbar puncture in children with significant neurological symptoms, which may show pleocytosis
• Blood cultures should be obtained to rule out bacterial infections Early diagnosis is crucial, and treatment with intravenous immunoglobulin (IVIG) at 2 g/kg as a single infusion, along with high-dose aspirin (80-100 mg/kg/day divided into four doses), should be initiated within the first 10 days of illness to reduce the risk of coronary artery aneurysms, as recommended by the American Heart Association guidelines 1.

From the Research

Diagnosis of Kawasaki Disease

The diagnosis of Kawasaki disease is made based on clinical findings 2. The following are the key components of the workup for Kawasaki disease:

• Clinical evaluation: The diagnosis relies on clinical findings, and laboratory tests are useful to rule out other causes of unexplained fever but are not specific for the diagnosis of KD 3.
• Laboratory tests:
  • Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are commonly used to assess inflammation, although discrepancies between the two tests can occur 4.
  • Platelet count and ESR have been shown to be good predictors of KD, with ESR having a sensitivity of 93.9% and specificity of 83.3% 5.
• Echocardiogram: To assess for coronary artery abnormalities, which are a common complication of KD 4, 6.
• Exclusion of other similar clinical entities: To confirm the diagnosis of KD 2, 3.

Atypical and Incomplete Kawasaki Disease

Patients who do not fulfill complete diagnostic criteria for KD are often referred to as atypical (or incomplete) KD 2, 6, 3. These patients are also at risk of developing coronary artery abnormalities and require careful evaluation and management.

Treatment and Follow-up

The treatment of KD typically involves the administration of intravenous immunoglobulin (IVIG) and aspirin, which has greatly reduced the incidence of coronary lesions in affected children 2, 6. Several other immune-modulating therapies have recently been utilized in complex or refractory cases 6. The approach to treatment and follow-up of KD is evolving, and guiding this evolution is the probability that the diagnosis is actually KD, the duration of the child's illness, and the desired effects of therapy 3.