Download PRACTICE GUIDELINES FOR COLLECTION OF THE BNP BLOOD

PRACTICE GUIDELINES FOR COLLECTION OF
THE BNP BLOOD TEST
FOR UNIVERSITY HOSPITAL SOUTH MANCHESTER
Please find attached guidelines for taking the B type Natriuretic Peptide (BNP) blood sample for
University Hospital South Manchester. B type Natriuretic Peptide is recommended by the NICE
and ESC guidelines as part of the pathway for Heart Failure (HF) diagnosis.
Heart failure is a complex clinical syndrome of symptoms and signs that suggest impairment
of the heart as a pump supporting physiological circulation. It is caused by structural or
functional abnormalities of the heart. The demonstration of objective evidence of these
cardiac abnormalities is necessary for the diagnosis of heart failure to be made.
The symptoms most commonly encountered are breathlessness (exertional dyspnoea,
orthopnoea and paroxysmal nocturnal dyspnoea) fatigue and ankle swelling.
Signs in heart failure could be due to pulmonary and systemic congestion, the structural
abnormalities causing heart failure, the structural abnormalities resulting from heart failure,
or from complications of therapy.
BNP guidance from NICE 2010 CG108 Chronic Heart Failure: Management of chronic
heart failure in adults in primary and secondary care.
Diagnosis:
1. Refer patients with suspected heart failure and previous myocardial infarction (MI)
urgently, to have transthoracic Doppler 2D echocardiography and specialist assessment
within 2 weeks. [new 2010]1
2. Measure serum natriuretic peptides (B-type natriuretic peptide [BNP] or N-terminal pro-Btype
natriuretic peptide [NTproBNP]) in patients with suspected heart failure without
previous MI. [new 2010]1
3. Because very high levels of serum natriuretic peptides carry a poor prognosis, refer
patients with suspected heart failure and a BNP level above 400 pg/ml (116 pmol/litre) or
an NTproBNP level above 2000 pg/ml (236 pmol/litre) urgently to have a transthoracic
Doppler 2D echocardiography and specialist assessment within 2 weeks. [new 2010]1
4.Refer patients with suspect heart failure and a BNP level between 100 and 400 pg/ml or an
NTproBNP level between 400 and 2000pg/ml to have a transthoracic Doppler 2D
echocardiography and specialist assessment within 6 weeks [new 2010]1.
5. Consider a serum natriuretic peptide test (if not already performed) when heart failure is still
suspected after transthoracic Doppler 2D echocardiography has shown a preserved left
ventricular ejection fraction. [new 2010]1.
1
ESC Guidelines for the diagnosis and treatment of
acute and chronic heart failure 2012 2
Suspected heart failure
Acute onset
Non-Acute onset
ECG
Chest X-ray
ECG
Possible chest x-ray
Echocardiography
Echo C
BNP/NT-proBNP
BNP/NT-proBNP
ECG normal and
NT-proBNP <300 pg/ml
or
BNP <100pg/ml
ECG abnormal
or
NT-proBNP ≥ 300pg/ml b
or
BNP ≥100pg/ml b
ECG abnormal
or
NT-proBNP ≥125pg/ml a
or
BNP ≥35pg/ml a
Echocardiography
ECG normal
and
NT-proBNP <125 pg/ml
or
BNP < 35 pg/ml
Heart Failure
Unlikely c
Heart Failure
Unlikely c
Echocardiography
If heart failure confirmed
determine aetiology and start
appropriate treatment
a Exclusion
cut off points for natriuretic peptides are chosen to minimise the false-negative rate while reducing unnecessary referrals for
echocardiography.
b Other
causes of elevated natriuretic peptide levels in the acute setting are an acute coronary syndrome, atrial or ventricular arrhythmias,
pulmonary embolism, and severe chronic obstructive pulmonary disease with elevated right heart pressures, renal failure and sepsis. Other causes
of an elevated natriuretic level in the non-acute setting are: old age (>75 years), atrial arrhythmias, left ventricular hypertrophy, chronic
obstructive pulmonary disease and chronic kidney disease.
c Treatment
may reduce natriuretic peptide concentration and natriuretic peptide concentration and natriuretic peptide concentrations may not be
markedly elevated in patients with Heart failure with Preserved Ejection Fraction.2
2
For University Hospital South Manchester collection of BNP blood sample
Be aware that:
Obesity or treatment with diuretics, angiotensin-converting enzyme (ACE) inhibitors, betablockers, angiotensin II receptor antagonists (ARBs) and aldosterone antagonists can reduce
levels of serum natriuretic peptides.
High levels of serum natriuretic peptides can have causes other than heart failure (for example,
left ventricular hypertrophy, ischaemia, tachycardia, right ventricular overload, hypoxaemia
[including pulmonary embolism], renal dysfunction [GFR <60ml/minute], sepsis, chronic
obstructive pulmonary disease, diabetes, age >70 years and cirrhosis of the liver). [new 2010]1.
BNP
Exhibits biological activity
Biological half-life ranges from 13-20 minutes
NTproBNP
Exhibits no biological activity
Biological half life ranges from 25-70
minutes
Actively cleared via clearance receptors and to Cleared passively by organs with high
a lesser extent by degradation. Also
blood flow (kidneys, the liver and muscles)
inactivated through kidneys
Extracted renally and increased with renal
Extracted renally (to similar extent) and
dysfunction
increased with renal dysfunction
In vitro stability of BNP is assay dependent.
Very stable at room temperature.
Values are stable for around 4 hours at room
temperature and should be measured as soon
as possible after blood draw.
LABORATORY INFORMATION AS PROVIDED BY UHSM
EDTA plasma sample
Results reported in ng/L
Samples need to be received same day (see above on stability of BNP)
Interpretative comments on all results
Result
BNP<100ng/L
UHSM Lab Interpretation
A diagnosis of heart failure is unlikely in an
untreated patient
Suggest refer for Echo and post Echo and
specialist assessment if appropriate in <6 weeks
Suggest refer for Echo and post Echo and
specialist assessment if appropriate in <2 weeks
BNP 100-400ng/L
BNP >400ng/L
3
Contacts at University Hospital South Manchester
Dr Graham Horsman
Consultant Chemical Pathologist
Biochemistry Department
Wythenshawe Hospital
0161 291 2132 (Direct)
0161 291 2122 (Secretary)
Dr Anne-Marie Kelly
Consultant Chemical Pathologist
Biochemistry Department
Wythenshawe Hospital
0161 291 4791 (Direct)
0161 291 2122 (Secretary)
Duty Biochemist
Biochemistry Department
Wythenshawe Hospital
0161 291 2136
References
1. NICE Clinical Guideline No 108. Chronic Heart Failure Guidelines
2. European Society of Cardiology for the diagnosis and treatment of acute and chronic heart
failure 2012.
4