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M.S. Singer, A.M. Fay; The Marginal Sensitivity of Serum Lysozyme and Angiotensin–Converting Enzyme in Orbital Sarcoidosis . Invest. Ophthalmol. Vis. Sci. 2005;46(13):5125.
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Purpose: Orbital inflammation is sometimes the first sign of systemic sarcoidosis. Clinical suspicion for sarcoidosis often prompts the clinician to test serum angiotensin–converting enzyme (ACE) and lysozyme. While these tests are moderately sensitive and specific in systemic sarcoidosis, it is not established whether both are indicated for patients who present with orbital disease. We tested the hypothesis that measuring ACE and lysozyme concurrently does not improve the sensitivity over measuring ACE alone in patients with suspected orbital sarcoidosis. Methods: We reviewed the records of seven patients who were suspected, based on history and exam at the time of presentation, to have orbital or lacrimal gland sarcoidosis. Serum ACE and lysozyme were tested in all patients (in the same laboratory) prior to biopsy or any treatment. Biopsy was then performed, and permanent tissue sections were assessed by an eye pathologist. Results: Biopsy demonstrated sarcoidosis in five patients and non–granulomatous inflammation in the remaining two. The latter two served as controls. All five patients with biopsy–proven sarcoidosis had abnormally elevated ACE levels (mean 98 units per liter; reference range 8–52 units per liter). In contrast, ACE was normal in both controls (mean 22 units per liter). Lysozyme was abnormally elevated in only three patients (60%) with sarcoidosis (over 22 mg per liter). Both control patients had normal lysozyme levels (mean 10 mg per liter). No significant correlation between ACE and lysozyme levels emerged from our sample (r = 0.34). Conclusions: These results suggest that for patients with suspected orbital sarcoidosis, testing both ACE and lysozyme provides no better sensitivity than testing ACE alone. For most patients, it is probably more clinically parsimonious and cost–effective to forego lysozyme testing.
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