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. Conclusion: 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.