title: The effect of potassium EDTA on the stability of parathyroid hormone in whole blood.
abstract: BACKGROUND
  The stability of parathyroid hormone (PTH) in whole blood has not been well characterized. Previous studies show EDTA plasma samples to be more stable than serum samples.
  
  
  METHODS
  Blood from 17 haemodialysis patients and five healthy volunteers was collected into serum separator tubes (SSTs) and potassium EDTA tubes (EDTA-Ts) and incubated at room temperature before separation and storage for PTH analysis using the Bayer Advia Centaur.
  
  
  RESULTS
  Initial PTH concentrations were 7% higher (95% confidence interval [CI] 2-16%, P=0.016) in EDTA-Ts compared to the SSTs in the renal cohort. PTH concentrations in SSTs were significantly lower after 8 (10%, 95% CI 3-17%) and 20 h (22%, 95% CI 11-31%) but did not change significantly in EDTA-Ts (P=0.1543). PTH concentration in EDTA-Ts from healthy volunteers was also independent of incubation time (P=0.1165).
  
  
  CONCLUSIONS
  The greater stability of PTH in whole blood anticoagulated with potassium EDTA allows PTH analysis to be offered to sites such as satellite clinics and primary care sites which do not have centrifugation and refrigeration facilities.
authors: Department of Clinical Biochemistry, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK.
authors: Emma
authors: E
authors: English
authors: Ian
authors: I
authors: McFarlane
authors: Kevin P
authors: KP
authors: Taylor
authors: David J
authors: DJ
authors: Halsall
mesh_terms: D016022:Case-Control Studies; D004492:Edetic Acid / Q000737:chemistry*; D006801:Humans; D010281:Parathyroid Hormone / Q000097:blood*; D006435:Renal Dialysis
chemical_list: D010281:Parathyroid Hormone; D004492:Edetic Acid