Introduction Silicosis is the result of silica exposure. Many chemotactic mediators arise with toxicity resulting from exposure to silica particles and silicotic nodules occur from the formation of collagen. Prolidase catalyses the hydrolysis of oligo/dipeptides which contains proline or hydroxyproline in the carboxyl terminal position. Many studies have identified prolidase activity at varying levels in fibrotic diseases. The aim of the study is to investigate the relationship between silicosis and prolidase activity.

Methods This study is a cross-sectional study. We reviewed medical records (functional status and radiological findings) and serum prolidase levels of 62 patients who were admitted to our centre between September and December 2015.

Result All cases were male and silicosis was diagnosed in 37 (%) of 62 cases. Prolidase level was significantly higher in patients with silicosis than in normal (p<0.001) (4877±2324 vs 815±520). Correlation analysis showed significant positive correlation between prolidase activity and ILO classification (r:0,723, p<0,001, figure 1A) and age (r: 0,391, p:0,002). Prolidase activity was negatively correlated with FEV1 (r:−0.332, p: 0.008) and FCV (r:−0.295, p:0.020).

Discussion Since prolidase is involved in collagen metabolism, its activity can be used for early diagnosis and follow-up of silicosis. Further studies are needed to clarify the etiopathogenetic mechanisms of silicotic nodule formation and early detection of vulnerable population who had silica exposure before nodule formation.