Average Blood Volume in Pediatric Patients
Pediatric blood volume is estimated at 70 mL/kg for children, but may be as high as 100 mL/kg in newborns. 1
Weight-Based Blood Volume Estimates
The most clinically useful approach to estimating pediatric blood volume is weight-based calculation, with important age-related variations:
Newborns and Young Infants
- Newborns have the highest blood volume per kilogram at approximately 85-100 mL/kg 1
- Infants 0-6 months with circulating blood volume of 80-85 mL/kg 1
- This higher volume reflects the physiologic needs of rapid growth and development 1
Older Infants and Children
- Children beyond the neonatal period have an estimated blood volume of 70-75 mL/kg 1
- Older infants (0.5-2 years): 75-80 mL/kg 1
- Children (2-11 years): approximately 75 mL/kg 1
- Adolescents (11-18 years): 70-75 mL/kg 1
Absolute Blood Volume by Weight Categories
Based on IDSA/ASM guidelines for blood culture collection, total patient blood volumes are stratified as follows 1:
- ≤1 kg: 50-99 mL total blood volume
- 1.1-2 kg: 100-200 mL total blood volume
- 2.1-12.7 kg: >200 mL total blood volume
- 12.8-36.3 kg: >800 mL total blood volume
- >36.3 kg: >2200 mL total blood volume
These values provide practical reference points for clinical decision-making regarding blood sampling, transfusion volumes, and assessment of blood loss 1.
Clinical Applications
Blood Product Dosing
Understanding pediatric blood volume is essential for appropriate transfusion therapy:
- RBC transfusion of 10 mL/kg increases hemoglobin by approximately 20 g/L 1, 2
- Fresh frozen plasma: 10-15 mL/kg 1, 2
- Platelets: 10-20 mL/kg 1, 2
- Cryoprecipitate: 5-10 mL/kg 1, 2
Blood Loss Assessment
- Children are at particular risk during major hemorrhage due to their smaller absolute blood volumes 1
- Each percentage of blood volume lost represents a more significant physiologic insult in smaller children 1
- Rapid administration of blood products requires careful monitoring for electrolyte imbalance and hypothermia 1, 2
Important Clinical Caveats
The 70 mL/kg estimate is a general guideline and does not account for individual variation. 1 Factors that may affect actual blood volume include:
- Hydration status
- Underlying medical conditions (particularly cardiac disease)
- Prematurity status in neonates
- Body composition variations
When calculating safe blood draw volumes or assessing hemorrhage severity, always use weight-based calculations rather than age-based estimates alone 1, as weight provides a more accurate reflection of total blood volume and physiologic reserve.