Dr Januzzi: If NT-proBNP is measured in a neonate or in a baby that’s about one or two days old, it is in the 5000 pg/mL to 10,000 pg/mL range. This has to do with the fact that in the peripartum period, at the near term and then in delivery, the infant’s cardiac output is in a hyperdynamic state, and they are volume overloaded. Babies also lose around 25% of their body weight in the first few days of life from diuresis. So in the first few days of life, the NT-proBNP value in a neonate is very frequently in the heart failure range. However, within the first week to two weeks after birth, it falls all the way down to very low values. This is the period recommended to test in the paediatric population to interpret the values after the initial period. If the NT-proBNP does not fall, it suggests the presence of a volume or pressure overload state such as patent ductus or congenital valve disease or complex congenital heart disease. By the time an infant is a toddler or early adolescent, NT-proBNP values are very interpretable.
