Extreme thrombocytosis in congenital diaphragmatic hernia patients suggests underlying splenic dysfunction during critical illness

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ESPR271
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Abstract: :

Background

Extreme thrombocytosis (EXT, platelet count >1000 x 103/ml) is an uncommon but potentially important clinical finding. EXT most commonly occurs secondary to infection, inflammation, iron deficiency, and/or splenic dysfunction. We recently defined clinical implications of EXT in hospitalized children (Thom et al, J Thromb Haemost 2020). Patients with congenital diaphragmatic hernia (CDH) were overrepresented in this EXT cohort.


Objective

To determine etiologies and sequelae of EXT in hospitalized pediatric patients, including those with CDH. 


Design/Methods

We retrospectively analyzed single-center cohort data from 79,618 patients in 131,982 admissions, including 366 CDH cases, from 2012 to March 2020.


Results

We identified EXT in 391 patients (0.5%) during 423 hospital admissions, often secondary to infection (47%), inflammation (40%), or iron deficiency anemia (5%). Few thrombotic or bleeding events were temporally associated with EXT, none of which definitively resulted from EXT. Critical illness was linked with EXT, as 55% of our cohort required pediatric, neonatal (NICU), and/or cardiac intensive care unit care. Reduced platelet storage and removal from hyposplenia or asplenia can also cause thrombocytosis. Although surgical splenectomy was rare (9 patients), splenic dysfunction was evident in cohort subpopulations. For example, autosplenectomy causes functional asplenia in many sickle cell patients by age 5. Among sickle cell patient admissions, EXT occurred mostly (85%) in those >5 years old. 


Infants with CDH can be critically ill due to pulmonary hypoplasia and pulmonary hypertension. Remarkably, among 49 NICU patients with EXT, 13 had CDH (4% of all CDH vs 0.5% of all NICU patients in the queried time period, p<0.0001 by two-sided Fisher's exact test). No infectious or inflammatory etiology was identified in 7/13 (54%) of CDH patients with EXT. This may suggest EXT from bone marrow hyperactivity following critical illness resolution. However, CDH patients with EXT were not among the most severely ill neonates, as none required extracorporeal membrane oxygenation support. Alternatively, our findings may indicate underlying splenic dysfunction. Indeed, one CDH patient with EXT underwent prior splenectomy. Splenic dysfunction was not clinically recognized in other CDH cases with EXT, but our findings may suggest transient splenic dysfunction from altered development, surgical manipulation, and/or hemodynamic instability in these otherwise unexplained cases.


Conclusions

Our findings will aid clinical interpretation when laboratory results identify EXT in hospitalized pediatric patients. In many pediatric cases, EXT occurred in response to inciting events in permissive physiologic contexts (e.g., infection with underlying asplenia). Many CDH patients with EXT had no clear inciting etiology. This may reflect underlying splenic dysfunction, and warrant consideration of associated management strategies in this fragile patient population.

Children's Hospital of Philadelphia
Children's Hospital of Philadelphia
Children's Hospital of Philadelphia
Children's Hospital of Philadelphia
Children's Hospital of Philadelphia

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