Preanalytical determinants of total and free prostate-specific antigen and their ratio: blood collection and storage conditions.

Author(s): Jung K, von Klinggräff P, Brux B, Sinha P, Schnorr D, Loening SA

Publication: Clin Chem, 1998, Vol. 44, Page 685-8

PubMed ID: 9510889 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   The purpose of this study was to determine the effects of storage of serum, whole blood, or plasma and freeze-thaw cycling on the measured concentrations of t-PSA and f-PSA in 18 patients with prostate cancer and 4 patients with benign prostatic hyperplasia. After experimental storage, serum and plasma were stored at -80 degrees C until analysis.

   Summary of Findings:

   Storage of serum at 37 degrees C for 1 h resulted in 5% decreases in t-PSA and f-PSA compared to initial levels, but after 24 h, levels had declined by less than 10%, and there was no change in the t-PSA/f-PSA ratio. When serum was stored at 4 degrees C or 22 degrees C, t-PSA and f-PSA declined compared to initial levels by 1 day and 4 h, respectively, after which time t-PSA levels continued to decline while f-PSA levels remained relatively constant. Consequently, there was a significant decrease in the t-PSA/f-PSA ratio in serum stored at 4 degrees C. Storage of serum at -80 degrees C for up to 4 months did not affect t-PSA or f-PSA levels. The authors report that t-PSA was stable in whole blood stored in serum or lithium heparin tubes at room temperature for up to 24 h, but that f-PSA declined by 5% within 8 h. After 5 freeze-thaw cycles, f-PSA was 5% lower in serum than after a single freeze-thaw cycle.

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Serum
   • Bodily Fluid - Plasma

   Preservative Types

   • Frozen

   Diagnoses:

   • Neoplastic - Benign
   • Neoplastic - Carcinoma

   Platform:

   Analyte	Technology Platform
   Protein	Immunoassay

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Storage	Storage duration	1 month 4 months 0 h 1 h 4 h 8 h 24 h 48 h 4 days 7 days 14 days
   Storage	Storage temperature	-80 degrees C 4 degrees C 22 degrees C 37 degrees C
   Storage	Time at room temperature	1 h 2 h 4 h 8 h 24 h
   Storage	Type of storage container	Plastic serum tube Lithium-heparin coated plastic tube
   Storage	Freeze/thaw cycling	1 cycle 2 cycles 3 cycles 4 cycles 5 cycles
   Biospecimen Aliquots and Components	Blood and blood products	Plasma Serum Whole blood
   Biospecimen Aliquots and Components	Centrifugation	Centrifugation delays investigated

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