|Year : 2004 | Volume
| Issue : 4 | Page : 39-40
Diagnosing sarcoidosis : What is the value of A.C.E ?
Gurdesh S Bedi, Rajinder S Bedi
Gurdesh S Bedi
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Bedi GS, Bedi RS. Diagnosing sarcoidosis : What is the value of A.C.E ?. Lung India 2004;21:39-40
Sarcoidosis remains one of the most enigmatic diseases in medicine. The diagnosis requires a compatible clinical picture, histologic demonstration of non-caseating granulomas, and exclusion of other diseases capable of producing a similar histological or clinical picture. No single test is pathognomonic of sarcoidosis.
Serum angiotensin - converting enzyme (ACE) estimation is frequently used for diagnosing sarcoidosis. Liberman (1975) was first to report that serum ACE was elevated in patients with sarcoidosis. ACE is a dipeptidyl carboxy peptidase, which catalyzes the conversion of angiotensin I to angiotensin II and helps metabolize bradykinin. ACE is found in the normal lung on the luminal surface of capillary endothelial cells. It also originates from active epithelioid cells, giant cells, alveolar macrophages and fibroblasts.
Serum levels of ACE are increased in 60-80% of patients with sarcoidosis. But this finding is not specific, and increased levels are also found in other diseases such as Gaucher's disease, atypical mycobacterial disease, leprosy, lymphangiomyomatosis, diabetes mellitus with severe retinopathy and osteo arthritis. ACE levels are also increased in alcoholic cirrhosis, primary biliary cirrhosis, inflammatory bowel disease, coccidioidomycosis, berylliosis, histoplasmosis, silicosis, asbestosis, hyperthyroidism and miliary tuberculosis.
Though the list of diseases associated with elevated ACE levels is large, yet sarcoidosis continues to be the most common cause of high serum ACE levels and all other causes combined count for less than 20% cases. A mildly elevated ACE is never diagnostic of sarcoidosis and an elevation greater than two times the upper limits of normal are much less common in other diseases listed above though occasionally can occur in other granulomatous diseases such as Gaucher's disease, tuberculosis and hyperthyroidism. ACE is also elevated in the bronchoalveolar lavage (BAL) fluid of patients with sarcoidosis.
Many believe that the magnitude of elevation of serum ACE reflects the granuloma load in sarcoidosis. But the serial measurements of ACE to monitor the course of disease and the response to steroid therapy can not be recommended since the elevated levels are neither sensitive nor specific for sarcoidosis. For instance, clinical or radiographic deterioration may occur without an associated rise in serum ACE, and clinical or radiographic improvement may occur without any fall in elevated ACE levels.
It can therefore be concluded that serum ACE results can be valuable in substantiating the diagnosis of sarcoidosis in a difficult case, but its serial estimations (a costly affair) can not be recommended for screening or monitoring the course of this disease.