From the Guidelines
Lysozyme is a useful marker of active sarcoidosis, as elevated serum levels are usually associated with more aggressive disease and multiple-organ involvement. According to the european position paper on rhinosinusitis and nasal polyps 2020 1, serum lysozyme levels, along with angiotensin converting enzyme (ACE) and soluble interleukin-2 (sIL-2R), have become useful tools in the diagnosis of sarcoidosis and for evaluating disease activity.
Key Points
- Elevated serum lysozyme levels can indicate active sarcoidosis, as this enzyme is produced by activated macrophages and epithelioid cells in sarcoid granulomas.
- Lysozyme has limited specificity, as it can also be elevated in other granulomatous diseases, tuberculosis, some leukemias, and renal failure.
- For monitoring sarcoidosis activity, lysozyme should be used alongside other markers like ACE, sIL-2R, imaging studies, and clinical assessment, as stated in the european position paper on rhinosinusitis and nasal polyps 2020 1.
Clinical Considerations
- Lysozyme may be particularly useful in patients taking ACE inhibitors, which can artificially lower ACE levels.
- The test is relatively inexpensive and widely available, making it practical for routine monitoring.
- Lysozyme levels typically decrease with successful treatment and disease remission, potentially helping clinicians assess treatment efficacy and guide management decisions, as suggested by the study 1.
From the Research
Lysozyme as a Marker of Active Sarcoidosis
- Lysozyme has been studied as a potential marker of active sarcoidosis in several research studies 2, 3, 4.
- The sensitivity of lysozyme for predicting sarcoidosis was found to be 79.1% in one study, which is higher than that of serum angiotensin-converting enzyme (ACE) 2.
- Serum lysozyme levels have been shown to correlate with clinical features of sarcoidosis, such as the number of organs involved and radiographic stages 2, 3.
- Lysozyme levels have also been found to decrease with treatment and increase with disease progression, suggesting its potential use in monitoring disease activity 3, 4.
- However, the specificity of lysozyme for sarcoidosis is lower than that of ACE, which may limit its diagnostic value 2, 5.
- Other studies have compared lysozyme to other biomarkers, such as KL-6 and chitotriosidase, and found that it may be useful in combination with other markers for diagnosis and prognosis of sarcoidosis 6, 5.
Comparison with Other Biomarkers
- Lysozyme has been compared to other biomarkers, such as ACE, KL-6, and chitotriosidase, in terms of its sensitivity and specificity for sarcoidosis 6, 5.
- KL-6 has been found to be a reliable biomarker of fibrotic lung involvement in sarcoidosis patients, while chitotriosidase has been associated with extrapulmonary localizations 6.
- ACE and lysozyme may be more useful for discarding sarcoidosis due to their higher specificity, while other biomarkers such as sIL-2R, CRP, and SAA may be more useful for confirming the diagnosis 5.
Clinical Utility
- Lysozyme may be a useful marker for monitoring disease activity in patients with proven sarcoidosis, particularly in combination with other biomarkers 2, 3, 5.
- The clinical utility of lysozyme and other biomarkers may depend on the specific clinical context and the presence of other diagnostic markers 5.