Serial chitotriosidase measurements in sarcoidosis--two to five year follow-up study.

INTRODUCTION: Chitotriosidase (CTO) is a human chitinolytic enzyme secreted by activated macrophages and polymorphonuclear neutrophils. Albeit not specific for sarcoidosis, it is increased in over 90% of patients with active disease. The aims of this study were to correlate CTO measurements with clinical assessment of sarcoidosis and to test CTO as a marker of sarcoidosis relapse.

METHODS: 95 patients were followed-up for 24-60 months. Serial CTO measurements were performed every 3-6 months and correlated to clinical symptoms, lung function (FVC and DLco) and chest X-ray. In 38 patients clinical outcome status (COS) at 5 years was determined.

RESULTS: Initial CTO levels were significantly higher in patients with impaired FVC/DLco (p = 0.011 for both) but there was no correlation with standard chest X-ray stages. Patients with Loefgren's syndrome had significantly lower initial and control CTO level compared to other patients (p = 0.011 and p = 0.001, respectively). At follow-up there was a positive correlation of CTO and deterioration of clinical symptoms (p < 0.001), chest X-ray (p < 0.001) and FVC/DLco (p = 0.012 and p = 0.086, respectively). Control CTO levels were significantly lower in no disease groups versus minimal or persistent disease group as defined by COS (p = 0.003 and p < 0.001, respectively). At relapse CTO increased for 100% or more from baseline value in 12/14 patients.

CONCLUSIONS: It was shown that CTO correlates with certain sarcoidosis phenotypes (Loefgren's syndrome, COS) and that serial measurements of CTO correlate with clinical symptoms, chest radiographs and lung function.