title: Cystatin C of pleural effusion as a novel diagnostic aid in pleural diseases of different aetiologies.
abstract: There has been considerable recent interest in the potential use of serum cystatin C as a diagnostic tool. Here we examined the hypothesis that the cystatin C level in the pleural effusion can differ from the corresponding serum level. We evacuated pleural effusion fluids from 47 patients by thoracentesis. Cystatin C, beta(2)-microglobulin, inorganic phosphate, creatinine and total protein were quantified in both pleural effusion fluids and corresponding sera. We determined cystatin C levels in pleural effusions and calculated the ratio of cystatin C levels in serum and effusion, to discriminate between effusions caused by severe renal impairment and other types of effusion. Extremely high concentrations of cystatin C in serum/effusion pairs were only measured in patients with renal failure (6.0 +/- 0.8/6.0 +/- 0.8 mg/l, means +/- S.D., n=11). A clearly defined region was found to correspond to pleural effusion caused by renal failure (r=0.954). The quantification of cystatin C in the effusion was justified by the discovery that there were some patients with a high serum cystatin C level but a low effusion concentration, or a low serum cystatin C but a high effusion concentration, indicating causes other than renal failure. In conclusion, the pilot data indicate a relationship between the cystatin C concentration in pleural fluid and the underlying disease. Thus cystatin C levels in pleural effusion and serum may be a valuable criterion for the differential diagnosis of pleural diseases of different aetiologies.
authors.affiliation: Department of Internal Medicine, Graz University M.S. and Hospital, A-8036 Graz, LKH, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Domej
authors.forename: Gernot Peter
authors.initials: GP
authors.lastname: Tilz
authors.forename: Zeno
authors.initials: Z
authors.lastname: Földes-Papp
authors.forename: Ulrike
authors.initials: U
authors.lastname: Demel
authors.forename: Thomas
authors.initials: T
authors.lastname: Rabold
authors.forename: Herwig
authors.initials: H
authors.lastname: Holzer
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D003404:Creatinine / Q000032:analysis / Q000097:blood; D055316:Cystatin C; D015891:Cystatins / Q000032:analysis* / Q000097:blood; D003937:Diagnosis, Differential; D005260:Female; D006333:Heart Failure / Q000378:metabolism; D006801:Humans; D008103:Liver Cirrhosis / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010710:Phosphates / Q000032:analysis / Q000097:blood; D010995:Pleural Diseases / Q000175:diagnosis / Q000378:metabolism*; D010996:Pleural Effusion / Q000378:metabolism; D016066:Pleural Effusion, Malignant / Q000378:metabolism; D011506:Proteins / Q000032:analysis; D051437:Renal Insufficiency / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000032:analysis
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D010710:Phosphates; D011506:Proteins; D001613:beta 2-Microglobulin; D003404:Creatinine