Pediatric immunology laboratory evaluation.

PURPOSE OF REVIEW: Laboratory evaluation of the immune system is an essential component of diagnostic workup for suspected immune disorders in pediatric patients. Because the immune system evolves rapidly across infancy and childhood, and age-specific reference ranges are limited for many assays, interpretation of immune laboratory results requires careful attention to developmental stage and clinical context. RECENT FINDINGS: Advances in pediatric immunology have improved understanding of normal, age-appropriate immune development. Consequently, there is growing recognition of the limitations of standard laboratory assays in children and the need for age-specific reference ranges. Developing and applying pediatric reference intervals remains challenging because of assay limitations, sample constraints, and biologic variability across patient populations, issues that are particularly important when interpreting quantitative and functional immune assays. SUMMARY: Accurate diagnosis of immune disorders in children depends on integrating clinical history, physical examination, laboratory trends, and developmental stage. Abnormal laboratory values may reflect normal maturation, benign variation, or transient effects of external factors such as infection rather than true disease. Conversely, reassuring results may still obscure clinically significant immune dysfunction if interpreted in isolation. A structured, age-aware approach to immune testing helps avoid misdiagnosis, supports timely recognition of true immunologic disease, and guides appropriate intervention.