Background The recent emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in a rapid proliferation of serologic assays. However, little is known about their clinical performance. Here, we compared two commercial SARS-CoV-2 IgG assays. Methods 103 specimens from 48 patients with PCR-confirmed SARS-CoV-2 infections and 153 control specimens were analyzed using SARS-CoV-2 serologic assays by Abbott and EUROIMMUN (EI). Duration from symptom onset was determined by medical record review. Diagnostic sensitivity, specificity, and concordance were calculated. Results The Abbott SARS-CoV-2 assay had a diagnostic specificity of 99.4% (95% CI; 96.41–99.98%), and sensitivity of 0.0% (95% CI; 0.00–26.47%) at <3 days post symptom onset, 30.0% (95% CI; 11.89–54.28) at 3–7d, 47.8% (95% CI; 26.82–69.41) at 8–13d and 93.8% (95% CI; 82.80–98.69) at ≥14d. Diagnostic specificity on the EI assay was 94.8% (95% CI; 89.96–97.72) if borderline results were considered positive and 96.7% (95% CI; 92.54–98.93) if borderline results were considered negative. The diagnostic sensitivity was 0.0% (95% CI; 0.00–26.47%) at <3d, 25.0% (95% CI; 8.66–49.10) at 3–7d, 56.5% (95% CI; 34.49–76.81) at 3–7d and 85.4% (95% CI; 72.24–93.93) at ≥14d if borderline results were considered positive. The qualitative concordance between the assays was 0.83 (95% CI; 0.75–0.91). Conclusion The Abbott SARS-CoV-2 assay had fewer false positive and false negative results than the EI assay. However, diagnostic sensitivity was poor in both assays during the first 14 days of symptoms.

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BACKGROUND Galectin-3 (Gal-3) has been suggested as a prognostic biomarker in heart failure (HF) patients that may better reflect disease progression than traditional markers, including B-type natriuretic peptide (BNP) and cardiac troponins. To fully establish the utility of any biomarker in HF, its biologic variability must be characterized. METHODS To assess biologic variability, 59 patients were prospectively recruited, including 23 male and 16 female patients with stable HF and 10 male and 10 female healthy individuals. Gal-3, BNP, and high-sensitivity cardiac troponin I (hs-cTnI) were assayed at 5 time points within a 3-week period to assess short-term biologic variability. Long-term (3-month) biologic variability was assessed with samples collected at enrollment and after 4, 8, and 12 weeks. RESULTS Among healthy individuals, mean short-term biologic variability, expressed as intraindividual CV (CVI), was 4.5% for Gal-3, 29.0% for BNP, and 14.5% for hs-cTnI; long-term biologic variability was 5.5% for Gal-3, 34.7% for BNP, and 14.7% for hs-cTnI. In stable HF patients, mean short-term biologic variability was 7.1% for Gal-3, 22.5% for BNP, and 8.5% for hs-cTnI, and mean long-term biologic variability was 7.7% for Gal-3, 27.6% for BNP, and 9.6% for hs-cTnI. CONCLUSIONS The finding that Gal-3 has minimal intraindividual biological variability adds to its potential as a useful biomarker in HF patients.

Hemophagocytic lymphohistiocytosis (HLH) is a rare, potentially fatal, syndrome of excessive and ineffective activation of the immune system. The majority of the reported data on HLH is from pediatric patients and lacks specificity. This makes HLH diagnosis challenging especially in adults where HLH is triggered by many conditions and can resemble many disease entities. Elevated ferritin is one of the diagnostic criteria for HLH. We determined the conditions associated with elevated ferritin at our medical center to assess how specific ferritin is for predicting HLH. We retrospectively reviewed all ferritin results >10,000 μg/L in pediatric and adult patients. The most common condition associated with elevated ferritin was hematologic malignancy in adults (25.7%) and HLH in pediatric patients (48.9%). HLH was diagnosed in 14.2% of adults and 48.9% of children with ferritin >10,000 µg/L. Hyperferritinemia occurs in a variety of conditions and is not specific for adult or pediatric HLH. Common causes of elevated ferritin should be considered before entertaining the possibility of HLH, especially in adult patients.