Predictive value of baseline serum angiotensin-converting enzyme (sACE) levels for steroid response in sarcoidosis

BACKGROUND AND OBJECTIVE: Sarcoidosis is a systemic granulomatous disease that primarily affects the lungs. Corticosteroids are the first-line therapy, but steroid resistance remains a major clinical challenge. This study evaluates baseline serum angiotensin-converting enzyme (sACE) levels as a potential biomarker for predicting steroid resistance in sarcoidosis. METHODS: In this prospective single-centre study, 188 patients with biopsy-confirmed sarcoidosis had baseline sACE levels measured before corticosteroid initiation using the Kasahara colorimetric technique. Associations between sACE levels and treatment response were analysed using logistic regression and ROC analysis (SPSS v21; significance at P < 0.05). RESULTS: The mean age of the cohort was 54 years, with 62% women. Common symptoms included cough, dyspnoea, fatigue, and arthralgia; hypercalcemia was seen in 11%. Elevated baseline sACE > 64 U/L was found in 41% of cases. ROC analysis yielded an (AUC) of 0.788 (95% CI: 0.685-0.891), with 83% sensitivity and 73% specificity for predicting steroid resistance. On multi-variate analysis, elevated sACE (P < 0.001), age > 54 years (P < 0.001), fatigue (P = 0.002), hypercalcemia (P = 0.019), and mediastinal lymph node involvement on CECT (P = 0.036) were independent predictors of poor steroid response. CONCLUSION: Elevated baseline sACE levels show potential as an adjunctive biomarker for identifying patients at risk of steroid resistance in sarcoidosis. However, given its moderate specificity and absence of longitudinal validation, sACE should be interpreted cautiously and in conjunction with clinical and radiological parameters. Multi-centre studies with longer follow-up are warranted to confirm these findings.