Elevated blood lactate in neonates

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An elevated blood lactate concentration can be a non specific sign that a neonate is significantly unwell

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Newborn intensive care

Blood lactate concentrations are frequently measured in sick neonates. Blood lactate concentrations may be elevated if there is severe organ dysfunction associated with decreased tissue perfusion, decreased oxygen delivery and /or increased metabolic demand. Therefore, an elevated blood lactate concentration can be a nonspecific sign that a neonate is significantly unwell.

First, consider whether the sample is adequate; capillary or venous lactate concentrations may be falsely high if it was a difficult collection or the sample was not analysed soon after collection. If in doubt, repeat a capillary sample from warmed foot, or collect a free flowing venous sample. If these remain elevated, consider an arterial blood lactate concentration and discussion with NICU specialist on call.

Differential diagnoses

If lactate concentration is persistently high (ie > 3.0 mmol/L) the differential diagnoses include:

Perinatal asphyxia

  1. Was the cord lactate elevated? (see obstetric high lactate guideline)

  2. Consider hypoxic ischaemic encephalopathy (see Observation and management of infants at risk of neonatal encephalopathy guideline)

Congenital heart disease

  1. Perform a cardiovascular examination, does the baby have a murmur? Absent femoral pulses? Cyanosis?

  2. Consider CXR/ECG +/- echocardiogram

  3. If the baby has been diagnosed with congenital heart disease and the cardiologists have requested regular blood lactate concentrations, notify cardiology if the blood lactate concentration is rising (see Cardiac – management of antenatally diagnosed major congenital heart disease at delivery and in NICU guideline)

Sepsis

  1. Does the baby have risk factors for sepsis or other signs of poor perfusion e.g. low urine output, hypotension, poor capillary refill?

  2. Note, that a normal lactate at presentation does not rule out severe sepsis.

  3. Consider checking a FBC/CRP and investigate for sepsis (see Antibiotics for neonatal sepsis guideline)

  4. Consider a bolus of normal saline +/- inotropes and discussing with NICU specialist.

Necrotising enterocolitis

  1. Perform an abdominal examination and consider an abdominal X-Ray series (see Necrotising enterocolitis (NEC) in the neonate guideline)

  2. Consider a surgical consultation. Discuss with NICU specialist first.

Inborn errors of metabolism

  1. Organic acidosis e.g. methylmalonic acidaemia, and primary lactic acidoses e.g. mitochondrial respiratory chain disorders, cause metabolic acidosis with increased anion gap.

  2. Consider a metabolic screen (see Metabolic disease in the newborn guideline)

  3. Consider a metabolic service consultation. Discuss with NICU specialist first.

 

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