To the Editor.
—It is well known that measuring serum angiotensin-converting enzyme (ACE) levels is a useful tool to regulate therapy in sarcoidosis and to confirm the diagnosis.1 Most recently, Thompson et al2 demonstrated that a single dose of 75 mg of prednisolone failed to alter serum ACE concentrations within a 24-hour period, and they suggested that two to four weeks of steroid therapy may be required before ACE concentrations fell. This decline in ACE concentration would be secondary to a reduction in the massive granulomas rather than a direct biochemical/receptor influence on ACE biosynthesis. Since active and continuous biosynthesis of ACE is carried out in granulomatous lesions of sarcoidosis,3 it is not considered that ACE concentration actively produced by sarcoid granulomas may alter before or after only a single dose of prednisolone. For a better understanding of the response of serum ACE concentrations for steroid therapy,