What is a normal lactate level for a child?

Normal Lactate Levels in Children

Normal lactate levels in children are below 2 mmol/L, which is the same threshold used in adults. 1, 2

Age-Specific Considerations

While the upper limit of normal remains consistent across pediatric age groups at <2 mmol/L, there are important developmental variations to understand:

Neonates and Preterm Infants

• Preterm infants (<32 weeks gestation) have physiologically higher lactate levels in the first 24 hours of life, with mean values of 4.63 mmol/L in the first 6 hours, declining to 2.08 mmol/L by 24 hours 3
• In this population, persistently elevated lactate >5.6 mmol/L has 100% sensitivity and 85% specificity for predicting adverse outcomes (death, severe intraventricular hemorrhage, or periventricular leukomalacia) 3
• The elevated early lactate in preterm neonates reflects normal transitional physiology and metabolic adaptation, not necessarily pathology 3

Older Infants and Children

• Beyond the neonatal period, the normal threshold of <2 mmol/L applies universally 2, 4
• Lactate levels ≤2 mmol/L can be measured from either venous or arterial samples interchangeably in children with sepsis 4
• When venous lactate exceeds 2 mmol/L, arterial confirmation is required because agreement between venous and arterial measurements becomes poor above this threshold (limits of agreement ±1.90 mmol/L) 4

Clinical Interpretation Framework

Mild Elevation (2-3 mmol/L)

• Indicates potential tissue hypoperfusion requiring investigation 2
• Can result from non-critical causes including recent exercise, medication effects, or mild hypoperfusion 2, 5
• Warrants close monitoring and repeat measurement to assess trends 5

Moderate Elevation (3-5 mmol/L)

• Associated with increased mortality risk in febrile children (odds ratio 1.6 compared to lactate ≤3 mmol/L) 6
• In pediatric trauma, lactate >3.2 mmol/L predicts need for transfusion 7
• Requires aggressive evaluation for underlying shock states 2

Severe Elevation (>5 mmol/L)

• In febrile children, lactate >5 mmol/L increases mortality odds 3.4-fold (5.1-8.0 mmol/L range) to 8.9-fold (>8.0 mmol/L) 6
• In pediatric trauma, lactate >5.1 mmol/L independently predicts mortality with adjusted odds ratio of 6.43 7
• Represents a medical emergency requiring immediate resuscitation 2

Critical Elevation (≥8 mmol/L)

• Defines refractory septic shock in children when combined with high vasoactive dependency or myocardial dysfunction 1
• Associated with dramatically increased mortality 6

Important Clinical Caveats

Labor transiently elevates lactate in pregnant patients, so this marker should not be used for sepsis diagnosis during active labor 2, 5. However, outside of labor, the normal threshold of <2 mmol/L applies to pregnant and postpartum patients 2, 5.

In children with brief resolved unexplained events (BRUE), lactate levels of 2-3 mmol/L often represent false positives, with only values >3 mmol/L being clinically significant 5.

Alcohol consumption can confound lactate interpretation, and base deficit may provide more reliable information in these cases 2.

The strong correlation between lactate and base deficit (R=0.8) means these markers provide complementary but independent information about tissue perfusion 3, 7. Both should be assessed when available, as they may diverge in certain clinical scenarios 1, 2.