A clinician may notice a change in serum brain natriuretic peptide (BNP) or NT pro-BNP levels over a few hours. The reason for the change can often be found be consideration of possible explanations.
Reasons for an increase in BNP or NT pro-BNP:
(1) treatment with nesiritide (synthetic natriuretic peptide given IV for severe CHF, increase in BNP only)
(2) exertion
(3) acute decompensation of heart failure
(4) error in specimen collection (first or second specimen from different patient)
(5) laboratory error
Reasons for a decrease in BNP or NT pro-BNP:
(1) rest after exertion
(2) successful treatment of heart failure
(3) error in specimen collection (first or second specimen from different patient)
(4) laboratory error
Type of Peptide
Half-Life
BNP
20 minutes
NT pro-BNP
90 (60 - 120) minutes
where:
• Common units for BNP are pg/mL and pM (1 pg/mL = 0.6 pM).
A common scenario may involve a patient who has the first sample drawn after exerting him/herself to get to the office, followed by a period of rest. A repeat sample tested for BNP drawn more than an hour later (> 3 half lives) may be significantly lower.
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