Role of serum angiotensin-converting enzyme (sACE) level as a biomarker for predicting steroid response in patients with sarcoidosis

Background: Sarcoidosis is a systemic inflammatory disease characterized by non-caseating granulomas in multiple organs, predominantly the lungs. Corticosteroids are the first-line treatment; however, steroid resistance remains a significant challenge. This study aims to evaluate serum angiotensin-converting enzyme (sACE) levels as a biomarker for predicting steroid resistance in sarcoidosis patients. Methods: This prospective study was conducted at a tertiary care center and included patients with biopsy-confirmed sarcoidosis. Serum ACE levels were measured after 4 to 6 weeks of corticosteroid therapy using the Kasahara colorimetric technique. The association between sACE levels and steroid resistance was evaluated. Statistical analysis was performed using SPSS version 20, with a significance threshold set at p < 0.05. Results: A total of 188 sarcoidosis patients (mean age: 54 years, 62% women) were included. Common symptoms included cough, dyspnea, fatigue, fever, chest pain, and arthralgia. Hypercalcemia was observed in 11% of patients. ROC analysis revealed that sACE >64 U/L had 83% sensitivity and 73% specificity in predicting steroid resistance. Univariate analysis identified fatigue, hypercalcemia, fibrosis on chest CT, and elevated sACE levels as associated factors, while multivariate analysis confirmed elevated serum ACE levels (p < 0.001), age >54 years (p < 0.001), fatigue (p = 0.002), hypercalcemia (p = 0.019), and specific radiological findings (e.g., CECT showing mediastinal lymph node involvement, p = 0.036) Conclusion: Serum ACE levels >64 U/L are a potential biomarker for steroid resistance in sarcoidosis. However, further research and a multidisciplinary approach are needed to validate these findings and improve clinical management.