2: Tube additives and cfDNA integrity: why EDTA still leads

Barra G et al., LabMed (2025) 2, 4 - A comparative study of blood collection tubes (EDTA, citrate, heparin, serum) from 15 healthy volunteers showing how anticoagulants affect baseline cell-free DNA, endogenous DNase activity, and cfDNA degradation over 24 hours at 37°C. Key terms: cell-free DNA, EDTA plasma, heparin plasma, citrate plasma, serum.

Study Highlights:
Baseline cfDNA was highest in serum and intermediate in heparin-plasma, while citrate- and EDTA-plasma had similarly low baseline cfDNA. Endogenous DNase activity was highest in heparin-plasma and serum, intermediate in citrate, and effectively inhibited in EDTA. After 24 h at 37°C, cfDNA degradation was greatest in heparin (85.3%) and serum (55.6%), with minimal loss in EDTA (8%) and low loss in citrate (13.3%). These results support EDTA-plasma as the preferred specimen for cfDNA analyses and caution against using heparin or serum.

Conclusion:
EDTA-plasma provides strong DNase inhibition and minimal cfDNA degradation and remains the gold standard for cfDNA analysis. Citrate-plasma shows partial DNase inhibition and low gDNA contamination and may be an acceptable alternative when EDTA is unavailable. Heparin-plasma and serum exhibit high DNase activity and substantial cfDNA degradation (plus known PCR inhibition for heparin), making them unsuitable for reliable cfDNA-based diagnostics.

QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2025-04-16.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 5
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license

Factual Items Audited:
- EDTA-plasma fully inhibits DNase activity and minimizes cfDNA degradation during a 24-hour ex vivo incubation at 37°C.
- Serum and heparin-plasma display high DNase activity and substantial cfDNA degradation after 24 h at 37°C (serum 55.6%, heparin 85.3%).
- Citrate-plasma shows intermediate DNase activity with 13.3% cfDNA degradation; EDTA shows 8.0% degradation, indicating partial inhibition by citrate and near-complete inhibition by
- Baseline cfDNA yields differ by tube type, with serum highest, EDTA and citrate lowest, and heparin intermediate (serum 1473 GE/mL; heparin 472 GE/mL; citrate 147.4 GE/mL; EDTA 154
- EDTA is the recommended gold standard for cfDNA analyses; citrate may be a secondary option; heparin and serum are unsuitable due to DNase activity and gDNA contamination.
- Baseline cfDNA yields (15 min) GE/mL by tube type

QC result: Pass.