Factors affecting soluble mesothelin related protein levels in an asbestos-exposed population.

BACKGROUND: Soluble mesothelin-related protein (SMRP) is increased in the sera of patients with malignant mesothelioma (MM), and has been suggested as a diagnostic tool for MM in an asbestos exposed population. However, factors affecting SMRP concentrations in normal subjects and those with other asbestos related disorders have not been investigated in any large population based study. METHODS: Five hundred and thirty-eight subjects with a history of asbestos exposure were studied. Age, height, weight, body mass index (BMI), serum creatinine and glucose, estimated glomerular filtration rate (eGFR) and lung function were compared with SMRP concentrations. RESULTS: The mean age [+/- standard deviation (SD)] of participants was 66.9 (+/-10.1) years, and mean (+/-SD) serum SMRP concentration was 0.91 (+/-0.67) nmol/L. SMRP values were inversely associated with weight (Pearson r=-0.1254, p=0.0036), BMI (Pearson r=-0.1594, p=0.0002), blood glucose (Pearson r=-0.1515, p=0.0004), single-breath carbon monoxide diffusing capacity (DLco) % predicted (Pearson r=-0.1847, p<0.0001), eGFR (Pearson r=-0.2835, p<0.0001) and single-breath carbon monoxide diffusing capacity per unit alveolar volume (DLco/VA)% predicted (Pearson r=-0.1872, p<0.0001) but were positively associated with age (Pearson r=0.2315, p<0.0001) and creatinine (Pearson r=0.3833, p<0.0001). CONCLUSIONS: This study has shown that demographic variables, physiological factors and lung function are associated with serum SMRP concentrations. Confounding factors should be considered when interpreting serum SMRP.