Distribution of Nonstandard Inflammatory and Cardiac Biomarker Levels in Children With Fever and Viral or Nonspecific Illness.

OBJECTIVES

To describe the distribution of laboratory values for nonstandard inflammatory and cardiac biomarkers in otherwise healthy children presenting to the pediatric emergency department (PED) with fever and viral or nonspecific illness.

METHODS

Single-center retrospective study of otherwise healthy children 3 months to 20 years presenting to the PED with fever and had a laboratory evaluation for multisystem inflammatory syndrome in children (MIS-C) between April 15, 2020 and January 24, 2022. All patients had NT-pro-b-natriuretic peptide (NT-proBNP) or troponin obtained (as part of an institutional pathway for MIS-C evaluation) during this period. Children with comorbidities, MIS-C, Kawasaki disease, myocarditis, or definitive non-viral illness were excluded. We summarized d-dimer, ferritin, troponin, and NT-proBNP distributions using descriptive statistics. One-way analysis of variance tested for differences among 3 disease categories: non-SARS-CoV-2 viral illness, fever not otherwise specified (NOS), and SARS-CoV-2 infection. Outlier values were identified as three times the interquartile range above the third quartile on box-and-whisker plots.

RESULTS

Of 134 eligible patients, 50, 65, and 19 were categorized as non-SARS-CoV-2 viral illness, fever NOS, and SARS-CoV-2 positive illness, respectively. Median age was 2 years. Median fever duration was 4 days, with 124/134 (93%) described as well-appearing and 112/134 (84%) discharged home. The median values for all biomarkers were within institutional laboratory reference ranges, with all distributions skewed to lower values, and without statistically significant differences between disease categories ( P > 0.05). D-dimer values were above the institutional reference range in 43/97 (44%), ferritin was above the reference range in 24/114 (21%), NT-proBNP was above the reference range in 26/123 (21%), and troponin levels were outside the range in 4/123 (3%). Thirteen patients had extreme outlier values.

CONCLUSIONS

Otherwise healthy children presenting to the PED with a fever and viral or nonspecific illnesses may frequently have elevated serum d-dimer, ferritin, and NT-proBNP above institutional reference ranges. Troponin elevation was infrequent.