Serum selenium and selenoprotein P in patients with silicosis.

OBJECTIVES: Selenoprotein P (SeP) is a selenium (Se) supply protein, which is an antioxidant micronutrient considered to be vital for human health. The aim of this study was to assess the serum selenium status in patients with silicosis. METHODS: We conducted a retrospective case-control study where serum samples from a total of 78 patients (males with a median age of 73.5 years old) with silicosis and 20 healthy controls (males with a median age of 72.5 years old) were assayed for Se and SeP. They underwent medical and job history taking, lung function testing, and chest radiography examinations. Levels of serum Se were measured using electrothermal atomic absorption spectrophotomerty, while levels of SeP were assessed with sandwich Enzyme Immunoassay. Spearman's rank correlation test was carried out to evaluate the relationship between Se and SeP. The Mann-Whitney test was used to evaluate differences in serum Se and SeP between study groups. RESULTS: The median serum Se and SeP concentrations were significantly lower in cases (74.0 µg/l and 4.2mg/l, respectively) compared with controls (116.0 µg/l and 5.8 mg/l, respectively). In both cases and controls, serum Se was positively correlated with serum SeP (rho=0.781, p<0.001 and rho=0.768, p<0.001, respectively). Serum Se and SeP levels were significantly lower in patients classified in category four compared with those who were classified in category two or three. CONCLUSIONS: Serum Se and SeP concentrations were found to be at inadequate levels in patients with silicosis, and decreased significantly with the severity of the disease.