title: Comparison of paired serum and lithium heparin plasma samples for the measurement of serum amyloid A in horses using an automated turbidimetric immunoassay.
abstract: This study aimed to evaluate whether equine serum amyloid A (SAA) concentrations could be reliably measured in plasma with a turbidimetric immunoassay previously validated for equine SAA concentrations in serum. Paired serum and lithium-heparin samples obtained from 40 horses were evaluated. No difference was found in SAA concentrations between serum and plasma using a paired t test (P=0.48). The correlation between paired samples was 0.97 (Spearman's rank P<0.0001; 95% confidence interval 0.95-0.99). Passing-Bablok regression analyses revealed no differences between paired samples. Bland-Altman plots revealed a positive bias in plasma compared to serum but the difference was not considered clinically significant. The results indicate that lithium-heparin plasma samples are suitable for measurement of equine SAA using this method. Use of either serum or plasma allows for greater flexibility when it comes to sample collection although care should be taken when comparing data between measurements from different sample types.
authors.affiliation: Clinical Diagnostic Laboratory, Department of Veterinary Clinical Medicine, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, CH-3012 Bern, Switzerland. Electronic address: judith.howard@vetsuisse.unibe.ch.
authors.forename: Judith
authors.initials: J
authors.lastname: Howard
authors.affiliation: Swiss Institute of Equine Medicine (ISME), Vetsuisse Faculty, University of Berne, Länggassstrasse 124, CH-3012 Bern, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Graubner
mesh_terms: D000818:Animals; D006493:Heparin / Q000097:blood; D006736:Horses / Q000378:metabolism*; D007118:Immunoassay / Q000662:veterinary*; D008094:Lithium / Q000097:blood; D009391:Nephelometry and Turbidimetry / Q000662:veterinary*; D000685:Serum Amyloid A Protein / Q000378:metabolism*
chemical_list: D000685:Serum Amyloid A Protein; D006493:Heparin; D008094:Lithium
keywords: Acute phase proteins; Anticoagulant effects; Horse; Plasma; Serum amyloid A