Brain Natriuretic Peptide BNP: Measurement

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Brain Natriuretic Peptide (BNP) Measurement

• Dr John Bartlett
• Western General Hospital

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Content of talk

• What is it all about?
• Measurement of BNP
• Summary

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What is it all about?

• BNP is a small peptide hormone released from the
  left ventricle (LV) and left atrium in response
  to increased ventricular volume/pressure or wall
  stretch
• BNP has haemodynamic effects which tend to
  improve LV function (vasodilatory, increased Na
  excretion)

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Measurement of BNP
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Assays for BNP

• Early clinical and basic research studies used
  the Shionogi assay
• Biosite triage assay introduced in 2000 (POCT)
• Rapid, automated assays now available
• Bayer assay (uses Shionogi antibodies)
• Roche assay (measures pro- N terminal BNP)

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ADVIA Centaur BNPAntibody Epitope Recognition
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Sample Collection

• Recommendations
• BNP is unstable in glass containers
• Recommended sample type is EDTA plasma using
  plastic tubes for sample collection
• Average recovery of BNP in uncentrifuged whole
  blood after 24h storage at 2 to 8 oC 96
• Samples are stable for at least 9 months when
  stored frozen at or below 20 oC

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Precision
a) Within batch precision
b) Between batch precision
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BNP degrades rapidly at room temperature

• Samples must be received within 24 hours.
• Frozen samples stable, and provide valuable
  back-up to samples shipped at RT.
• Insurance policy for study

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Conclusions

• A BNP sample, shipped at RT is stable for 24
  hours
• Degradation is a risk beyond this time.
• Frozen samples provide a valuable back up in case
  of assay problems.
• They also allow assay of other markers of cardiac
  damage
• Troponin I etc.

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Cardiac study patients (UK only).

• Consent patient to cardiac study (UK only)
• Collect samples
• Randomisation
• Post chemo-preRT
• Post RT
• 1 year
• 5 years
• At relapse
• BNP sample whole blood, ship RT at ONCE.
• Separate serum/plasma within 30 minutes.
• Store at -80?C
• Batch ship to central lab.

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Laboratory pack

• Laboratory Requisition Form (3 copies).
• colour coded tubes provided, add labels
  (pre-printed).
• Pasteur pipettes (x 5, including 1 spare)
• Tube and jiffy bag (addressed) for immediate
  dispatch of BNP sample (UK).
• Place 1 LRF with BNP sample (UK) post
  immediately, must arrive within 48 hours.
• Place 1 LRF with other samples, free -80C (-20
  C). Batch ship to central lab.
• Final LRF in patient file.

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How can we help?

• Do you need training?
• Do you have the appropriate equipment?
• What can we do to make life easier?

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The End