Pathophysiology
Clinical meaning
Pediatric red flags represent clinical findings that indicate potentially life-threatening conditions requiring immediate evaluation. Children compensate for physiological stress differently than adults: tachycardia is the earliest sign of shock, while hypotension is a late and ominous finding indicating loss of approximately 25-30% of blood volume. The immature immune system in neonates produces blunted inflammatory responses, making fever in infants under 28 days a medical emergency requiring full sepsis workup because clinical appearance alone cannot exclude serious bacterial infection. Developmental regression (loss of previously acquired milestones) always indicates pathology such as neurodegenerative disease, brain tumor, or metabolic disorder and is never normal variation.