NPPB and infection: • Ferritin as a second-line investigation.• Coagulation panel, fibrinogen, and D-dimers.• Troponin levels and brain natriuretic peptide/pro-brain natriuretic peptide should also be considered.• Blood culture, urine culture, and respiratory pathogen panel.• Electrocardiogram.• Echocardiography.• Chest radiographs.• Abdominal echography.• Cytokine panel.• Viral serologies and blood PCR for pathogen-specific infections.• Antiphospholipid panels.• Complement workup.• Quantitative serum immunoglobulins.