Reconsideration of the cut-off value of angiotensin-converting enzyme for screening of sarcoidosis in Japanese patients.

• Serum angiotensin-converting enzyme (ACE) levels are decreased by ACE inhibitors. • Three-fourths of Japanese patients with sarcoidosis have normal ACE values (<25.0 IU/L). • The possibility of sarcoidosis cannot be ruled out with the current standard value. • The sensitivity to detect sarcoidosis increases using the cut-off value of 17.7 IU/L. • Careful interpretation of this biomarker is needed. In clinical practice, we frequently experience patients with sarcoidosis who show relatively high but normal values of angiotensin-converting enzyme (ACE). The objective of this study was to reconsider the cut-off value of ACE. We studied 79 Japanese patients who were diagnosed as having sarcoidosis at our hospital. We excluded patients who had taken steroids or ACE inhibitors and patients with renal impairment. We respectively evaluated ACE values and performed receiver operating characteristic (ROC) analysis from a comparison with data for 299 normal Japanese subjects who showed ACE values in the current Japanese standard normal range (7.0–25.0 IU/L). Patients with sarcoidosis had higher ACE values than those in normal subjects (ACE: 20.3 IU/L [IQR, 16.0–24.4] vs. 15.4 IU/L [IQR, 12.8–18.5]; p < 0.001). However, 62 patients (78.5%) had normal ACE levels (cut-off value <25.0 IU/L), and the sensitivity of ACE level for detecting sarcoidosis was only 21.5%. From ROC analysis, a cut-off value of 17.7 IU/L (AUC: 0.727, 95% CI: 0.660–0.794, p < 0.001) was the best cut-off value for detecting sarcoidosis and sensitivity increased to 67.0%. The possibility of sarcoidosis cannot be ruled out by using the current Japanese standard value even in patients who have normal ACE levels. Careful interpretation of this biomarker is needed. [ABSTRACT FROM AUTHOR]