Question

A 2-year-old child presents with persistent fever for 4 days. Examination shows conjunctival injection and periungual desquamation, but criteria for complete Kawasaki disease are not met. You plan to evaluate for incomplete Kawasaki disease as per AHA guidelines. Which of the following investigations is NOT routinely recommended in this evaluation?

• A. Serum ferritin
• B. Serum albumin
• C. Urine WBC
• D. Complete blood count

Hint:

Remember the 6 AHA supplemental criteria for incomplete KD: Albumin $\le 3\text{ g/dL}$, Anemia, Elevated ALT, Platelets $>450\text{k}$ (after day 7), $\text{WBC} \ge 15,000/\mu\text{L}$, and Sterile pyuria ($\ge 10\text{ WBC/HPF}$). Ferritin is not included!

Answer 1

The Correct Option is A

Concept:
Incomplete (atypical) Kawasaki disease (KD) is suspected in infants and children who have prolonged unexplained fever with fewer than four of the classic diagnostic criteria.
The American Heart Association (AHA) provides a well-defined diagnostic algorithm comprising specific laboratory parameters and echocardiography to guide evaluation and treatment in these suspected cases.
Explanation:
• Kawasaki disease is an acute, self-limiting systemic vasculitis primarily affecting medium-sized arteries, especially the coronary arteries, in children younger than 5 years of age.

• When a child presents with fever for $\ge 4$--$5$ days and fewer than four principal clinical features, an algorithm based on laboratory findings is utilized to confirm incomplete Kawasaki disease.

• The initial workup recommended by the AHA guidelines includes inflammatory markers, specifically C-reactive protein (CRP $\ge 3\text{ mg/dL}$) and erythrocyte sedimentation rate (ESR $\ge 40\text{ mm/hr}$).

• Supplemental laboratory criteria include:
1. Serum albumin $\le 3.0\text{ g/dL}$
2. Anemia for age (evaluated on complete blood count)
3. Platelet count $>450,000/\text{mm}^3$ after day 7
4. White blood cell count $\ge 15,000/\text{mm}^3$
5. Serum alanine aminotransferase (ALT) elevation
6. Urine $\text{WBC} \ge 10/\text{HPF}$ (sterile pyuria)

• Serum ferritin is not a component of the standard AHA algorithm for incomplete KD; it is predominantly measured when evaluating for secondary Hemophagocytic Lymphohistiocytosis (HLH) or Macrophage Activation Syndrome (MAS).
Final Answer:
Serum ferritin is not routinely recommended as part of the supplemental laboratory algorithm for evaluating incomplete Kawasaki disease according to the AHA guidelines.