Elevated Platelet Counts After Kawasaki Disease in Children

Post-Kawasaki disease follow-up shows persistently elevated platelet levels?

I would like to ask the doctor: My daughter is currently 1 year and 1 month old.
When she was 6 months old, she was diagnosed with Kawasaki disease.
Initially, her platelet count was measured at 410,000/mm³.
After treatment with intravenous immunoglobulin to reduce fever, her platelet count peaked at 1,080,000 within a month.
Two months later, her platelet count decreased to 610,000.
A subsequent echocardiogram showed no dilation of the blood vessels, which was normal, and she has not taken low-dose aspirin since then.
Six months later, her platelet count was still 590,000, her white blood cell count was normal, and her echocardiogram was normal.
I would like to know if her platelet count is considered high, whether it might decrease naturally, or if we need to consult a pediatric hematologist to investigate the cause.
Is it appropriate for such a young child to take aspirin? Thank you!

Yan, 30~39 year old female. Ask Date: 2018/01/30

Dr. Xiao Kaiwen reply Pediatrics

Although Kawasaki disease has passed the acute phase, there may still be a prolonged period of elevated platelet counts.
There is no need to be overly concerned about the blood test results, but to prevent coronary artery lesions, please collaborate with your attending physician.
Initially, you should take low-dose aspirin for a period of time, followed by monitoring with echocardiograms and blood tests.
Aspirin may be discontinued later on.
After that, annual echocardiographic follow-ups will be necessary.
Therefore, I believe it is essential for you to work closely with your attending physician at this time.

Reply Date: 2018/01/30

More Info

Kawasaki disease (KD) is a serious condition that primarily affects children and can lead to significant cardiovascular complications if not treated promptly. It is characterized by prolonged fever, rash, conjunctivitis, and changes in the lips and oral cavity, among other symptoms. One of the notable complications of Kawasaki disease is the elevation of platelet counts, which can persist even after the acute phase of the illness has resolved.

In your case, your daughter experienced a significant elevation in platelet counts following her diagnosis of Kawasaki disease. Initially, her platelet count was 410,000/mm³, which is already above the normal range. After treatment with intravenous immunoglobulin (IVIG), her platelet count peaked at 1,080,000/mm³, which is considerably high. Over the following months, her platelet count decreased to 610,000/mm³ and has remained around 590,000/mm³ for the past six months.

Elevated platelet counts, or thrombocytosis, are common after Kawasaki disease due to the inflammatory response triggered by the illness. The body often produces more platelets in response to inflammation, and this can take time to normalize. In many cases, platelet counts will gradually decrease as the inflammation subsides, but this process can vary significantly from one child to another.

1. Is her platelet count still considered high? Yes, while her platelet count has decreased from its peak, a count of 590,000/mm³ is still above the normal range for children, which is typically between 150,000 and 450,000/mm³. However, it is not uncommon for children who have had Kawasaki disease to have persistently elevated platelet counts for several months or even years after the acute phase.

2. Will the platelet count naturally decrease? It is possible that her platelet count may continue to decrease over time as her body recovers from the inflammation caused by Kawasaki disease. Regular monitoring of her blood counts is essential to track any changes. If the platelet count remains elevated for an extended period, further evaluation may be warranted to rule out other underlying conditions.

3. Should she see a pediatric hematologist? If her platelet count does not decrease or if there are any other concerning symptoms, it may be beneficial to consult a pediatric hematologist. They can provide a more comprehensive evaluation and determine if any additional testing or treatment is necessary.

4. Is low-dose aspirin appropriate for her? Low-dose aspirin is commonly prescribed for children who have had Kawasaki disease to reduce the risk of coronary artery complications. Since your daughter has had a history of Kawasaki disease, it is advisable to discuss with her pediatric cardiologist whether she should resume low-dose aspirin therapy, especially considering her elevated platelet counts.

5. What should you do next? Continue to monitor her platelet counts and maintain regular follow-ups with her pediatrician and cardiologist. They will guide you on the appropriate management and any necessary interventions. It is also important to watch for any signs of complications, such as chest pain or unusual fatigue, and report these to her healthcare provider immediately.

In summary, while your daughter's elevated platelet counts are concerning, they are not uncommon following Kawasaki disease. With careful monitoring and collaboration with her healthcare team, you can ensure that she receives the best possible care as she continues to recover.

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