C-peptide in dried blood spots.

Author(s): Johansson J, Becker C, Persson NG, Fex M, Törn C

Publication: Scand J Clin Lab Invest, 2010, Vol. 70, Page 404-9

PubMed ID: 20602576 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 patient age, serum dilution buffer, contamination of serum with hemolysate and storage of DBS and DBS eluates on the measurement of c-peptide. Whole blood was spotted onto filter paper and stored for 3 days or 6 months, in plastic, at room temperature, without direct light, before extraction. Eluates from DBS, serum, and red blood cells from sodium-heparin plasma in TBST or L2Pez buffer were frozen at -20 degrees C.

   Summary of Findings:

   A 1:2 dilution of serum in either TBST or L2Pez buffer led to the expected reduction in c-peptide levels, but when serum was diluted 1:2 in TBST or L2Pez buffer with hemolysed red blood cells, only 19% and 24% as much c-peptide was measured, respectively. The median c-peptide level in serum was 0.90nmol/L, while the median c-peptide level in DBS was 0.046 nmol/L. C-peptide levels increased with patient age and decreased with increasing storage duration of DBS eluates at -20 degrees C, but levels were not affected by storage of DBS at room temperature. The authors provide a formula to convert DBS c-peptide values to serum c-peptide values with adjustments for patient age and storage duration of DBS eluates.

   Biospecimens

   • Bodily Fluid - Blood
   • Bodily Fluid - Serum

   Preservative Types

   • Other Preservative
   • Frozen

   Diagnoses:

   • Normal

   Platform:

   Analyte	Technology Platform
   Protein	Immunoassay
   Protein	Clinical chemistry/auto analyzer

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Biospecimen Preservation	Type of fixation/preservation	Air-dried Frozen
   Biospecimen Aliquots and Components	Blood and blood products	Serum Whole blood
   Biospecimen Aliquots and Components	Biospecimen components	TBST buffer L2Pez buffer Hemolysed red blood cells No hemolysed red blood cells
   Storage	Storage duration	3 days 6 months
   Storage	Storage conditions	As an eluate DBS

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