Impact of systemic steroids on asthma biomarkers: A comprehensive analysis

Asthma is a chronic inflammatory airway disease characterized by variable airflow obstruction and bronchial hyperresponsiveness, affecting millions worldwide and showing heterogeneity in its endotype, clinical presentation, and severity. Following the principles of modern precision medicine, studying an asthmatic patient involves collecting various biomarkers that may assist in diagnosis, management, and characterization of the disease to predict clinical outcomes and treatment responses. Although systemic corticosteroid use should be limited to specific situations, this therapy still plays a crucial role in managing an asthmatic patient, especially during exacerbations. While it is known that steroids can affect biomarkers, the extent of this impact is often unclear. This remains an open issue, particularly in patients with severe asthma, where systemic steroids are more frequently used and biomarker measurement can deeply influence management and even access to therapy. Misinterpreting biomarkers can lead to over- or underestimating asthma severity, potentially resulting in serious consequences. In this comprehensive analysis, we have collected the available literature data on how systemic corticosteroids can affect different biomarkers used in clinical practice and research setting, categorizing them into humoral (eg, blood eosinophil count, total and specific IgE, alfa-1 antitrypsin, interleukins, eosinophil cationic protein, and thymic stromal lymphopoietin), instrumental (eg, spirometry, impulse oscillometry, fractional and multiple flow exhaled nitric oxide, and nasal nitric oxide), and clinical (ear-nose-throat and gastroenterological evaluation). The goal is to provide a practical and concise overview of this impact to assist clinicians in interpreting biomarkers independently of steroid therapy. Research should focus on developing predictive models that adjust individual biomarker readings for steroid dosage and duration, as well as markers less affected by corticosteroid interference. A detailed understanding of steroid-induced biomarker modulation is crucial for accurate asthma phenotyping, personalized treatment choices, and avoiding adverse outcomes caused by both under- and overtreatment. Going forward, integrating improved biomarker correction methods, enhancing patient education on steroid use, and continuing research into new inflammatory markers will be crucial for improving the accuracy and effectiveness of asthma management.