title: Stability of parathyroid hormone ex vivo in haemodialysis patients.
abstract: BACKGROUND
  The stability of parathyroid hormone (PTH) in blood ex vivo is a significant practical problem for laboratories and clinicians. Several studies have suggested that PTH is more stable in blood collected into a potassium edetate (EDTA) preservative.
  
  
  METHODS
  To confirm that this was applicable to renal dialysis patients using our assay (Nichols chemiluminescence), we examined PTH stability in 13 patients with end-stage renal failure using three different blood collection tubes.
  
  
  RESULTS
  PTH remained stable in EDTA plasma for up to 48 h at room temperature. PTH was significantly reduced in serum collected into plain tubes after 2 h, and after 4 h in serum collected into serum separator tubes, at room temperature.
  
  
  CONCLUSIONS
  In the assessment of renal osteodystrophy, the use of EDTA plasma can confer significant benefit, especially in busy laboratories where rapid frozen separation of blood may be hard to achieve.
authors.affiliation: Department of Clinical Biochemistry, East Kent Hospitals NHS Trust, William Harvey Hospital, Ashford TN24 0LZ, UK. teresa.teal@ekht.nhs.uk
authors.forename: T K
authors.initials: TK
authors.lastname: Teal
authors.forename: M
authors.initials: M
authors.lastname: Reed
authors.forename: P E
authors.initials: PE
authors.lastname: Stevens
authors.forename: E J
authors.initials: EJ
authors.lastname: Lamb
mesh_terms: D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D008163:Luminescent Measurements; D010281:Parathyroid Hormone / Q000097:blood* / Q000737:chemistry*; D006435:Renal Dialysis; D051437:Renal Insufficiency / Q000097:blood; D013048:Specimen Handling; D013696:Temperature; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone; D004492:Edetic Acid