title: Determination of optimal storage temperature and duration for analysis of total and isoenzyme lactate dehydrogenase activities in canine serum and cerebrospinal fluid.
abstract: BACKGROUND
  Lactate dehydrogenase (LDH) exists as 5 isoenzymes in both serum and cerebrospinal fluid (CSF). Human studies have demonstrated that changes in LDH activity can be correlated with a particular disease.
  
  
  OBJECTIVE
  Conflicting reports regarding the stability of LDH made it necessary to determine storage conditions before further study of the diagnostic power of this enzyme's activity can be pursued in dogs. The purpose of this study was to optimize measurement of LDH activity and analysis of its isoenzyme profile in canine serum and CSF through proper storage.
  
  
  METHODS
  Serum and CSF were collected from 5 healthy dogs. Samples were stored at 22°C, 4°C, or -20°C for up to 2 months. Total LDH activity was measured spectrophotometrically. Isoenzyme profiles were determined using the QuickGel LDH Isoenzyme technique and densitometric scanning. Retention of > 70% LDH activity in stored samples was considered clinically acceptable.
  
  
  RESULTS
  Serum and CSF stored at -20°C retained > 85% of the total LDH activity for 4 weeks, although CSF total LDH activity degraded by > 10% within 24 hours of storage. All serum LDH isoenzymes retained > 85% activity for up to 4 weeks at -20°C. CSF LDH isoenzyme activity degraded rapidly, therefore CSF LDH should be evaluated within 72 hours to assure > 75% of LDH isoenzyme activity.
  
  
  CONCLUSIONS
  Proper storage at -20°C can optimize detection of total LDH activity and the LDH isoenzyme profile in canine serum and CSF. This information is important for evaluating the potential usefulness of LDH in veterinary medicine.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Houle
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
authors.forename: Annie V
authors.initials: AV
authors.lastname: Chen
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
authors.forename: Amanda C
authors.initials: AC
authors.lastname: Brenna
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
authors.forename: Katrina L
authors.initials: KL
authors.lastname: Mealey
authors.affiliation: Department of Crop and Soil Sciences, College of Agricultural Sciences, Washington State University, Pullman, WA, USA.
authors.forename: Alecia M
authors.initials: AM
authors.lastname: Kiszonas
mesh_terms: D000818:Animals; D004285:Dogs / Q000097:blood* / Q000134:cerebrospinal fluid*; D007527:Isoenzymes / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*; D013048:Specimen Handling / Q000379:methods / Q000662:veterinary*; D013696:Temperature
chemical_list: D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase
keywords: Biomarker; dog; gel electrophoresis; isoenzyme; storage