Stability and validity of intact parathyroid hormone levels in different sample types and storage conditions.
Author(s): Khalil H, Borai A, Dakhakhni M, Bahijri S, Faizo H, Bokhari FF, Ferns G, Mirza AA
Publication: J Clin Lab Anal, 2021, Vol. , Page e23771
PubMed ID: 33792964 PubMed Review Paper? No
Purpose of Paper
This paper investigated the effects of a 2 h processing delay and up to 8 days of post-separation storage on intact parathyroid hormone (iPTH) levels in EDTA plasma and serum. Levels of iPTH were also compared in EDTA plasma, serum separator tube (SST) serum, and plain serum that were obtained without delay and analyzed immediately.
Conclusion of Paper
Levels of iPTH were comparable in EDTA plasma, SST serum and plain serum when blood was centrifuged immediately after collection and analyzed without delay. iPTH levels declined when blood in EDTA or plain serum tubes was subjected to a 2 h centrifugation delay. Levels of iPTH were significantly lower when plasma or serum were stored before analysis with the lowest levels found on day 8 of room temperature storage. The declines in iPTH only exceeded the total allowable error (30%) when plasma was stored at room temperature for 8 days and when serum was stored for ≥2 days at room temperature.
Studies
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Study Purpose
This study investigated the effects of a 2 h processing delay and up to 8 days of post-separation storage on iPTH levels in EDTA plasma and serum. Levels of iPTH were also compared in EDTA plasma, SST serum, and plain serum that were obtained without delay and analyzed immediately. Blood was collected from 30 healthy patients into plain, SST II Advanced gel tubes without additives, and K2EDTA Vacutainer tubes. Plasma and serum were isolated from blood by centrifugation at 3500 rpm for 10 min immediately and 2 h after blood collection. The plasma and serum from the immediately centrifuged specimens were stored at room temperature (24°C), 4°C, or −20°C for 0, 2, 4, or 8 days before analysis. iPTH levels were measured using an Architect i2000 instrument. Significance was evaluated by ANOVA and changes compared to the Clinical Laboratory Improvement Amendments total allowable error for iPTH of 30%.
Summary of Findings:
Levels of iPTH were comparable in EDTA plasma, SST serum, and plain serum when blood was centrifuged immediately after collection and analyzed without delay (67.3 ± 26.0 pg/mL, 65.9 ± 24.8 pg/mL, and 67.8 ± 25.9 pg/mL, respectively). iPTH levels were 7.4% lower when blood in EDTA tubes was subjected to a 2 h centrifugation delay (P<0.0001) and 3.8% lower when blood in plain tubes was subjected to a 2 h delay (P=0.003). Levels of iPTH were significantly lower when plasma or serum were stored before analysis with the lowest levels found on Day 8, regardless of storage temperature (P<0.001, all). Importantly, the largest declines were found when serum or plasma were stored at room temperature. The declines in iPTH only exceeded the total allowable error (30%) when plasma was stored at room temperature for 8 days and when serum was stored for ≥2 days at room temperature.
Biospecimens
Preservative Types
- None (Fresh)
- Frozen
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Peptide Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Aliquots and Components Blood and blood products Serum
Plasma
Biospecimen Aliquots and Components Centrifugation Centrifugation delays investigated
Storage Time at room temperature 0 h
2 h
Storage Storage temperature 24°C (room temperature)
4°C
−20°C
Storage Storage duration 0 days
2 days
4 days
8 days