Normal Blood Pressure in Pediatric Patients
Normal blood pressure in children is defined as systolic and diastolic values below the 90th percentile for age, sex, and height, with specific thresholds varying by these parameters and requiring reference to standardized tables for accurate classification. 1
Blood Pressure Classification by Age Group
Children Under 13 Years
- Normal BP: <90th percentile for age, sex, and height 1
- Elevated BP: ≥90th percentile but <95th percentile for age, sex, and height 1
- Stage 1 Hypertension: ≥95th percentile for age, sex, and height 1
- Stage 2 Hypertension: ≥95th percentile + 12 mm Hg 1
Adolescents ≥13 Years
The 2017 American Academy of Pediatrics guidelines align with adult definitions for this age group:
- Normal BP: <120/<80 mm Hg 1
- Elevated BP: 120-129/<80 mm Hg 1
- Stage 1 Hypertension: ≥130/80 mm Hg 1
- Stage 2 Hypertension: ≥140/90 mm Hg 1
Age-Specific Reference Values
One-Year-Old Children
- Normal systolic: 98-106 mm Hg at the 95th percentile (varies by height percentile) 2
- Normal diastolic: 55-59 mm Hg at the 95th percentile (varies by height percentile) 2
- Values below the 90th percentile are considered normal 2
Three-Year-Old Children
- Normal range at 50th percentile: Approximately 95-105 mm Hg systolic and 56-69 mm Hg diastolic 3
- Values must be interpreted using age-, sex-, and height-specific tables 3
Critical Implementation Points
Use of Normative Tables
The 2017 AAP guidelines introduced revised BP tables based exclusively on normal-weight children (BMI <85th percentile), resulting in values 2-3 mm Hg lower than previous tables that included overweight and obese children. 1
Simplified Screening Table
- A simplified screening table based on the 90th percentile BP for age and sex at the 5th height percentile provides >99% negative predictive value 1
- This simplified table is for screening only and should NOT be used to diagnose hypertension 1
- If screening values are elevated, full age-sex-height tables must be consulted, as cutoffs may be up to 9 mm Hg higher depending on the child's specific parameters 1
Height Adjustment is Essential
- Height significantly affects BP values, with a 9-21% range in both systolic and diastolic values across different height percentiles within the same age group 4
- More short children (10th height percentile) and fewer tall children (90th height percentile) are classified as hypertensive when height is properly accounted for 5
Diagnostic Confirmation Requirements
Never diagnose hypertension based on a single measurement. 1, 2, 3
- Elevated BP or hypertension must be confirmed on three separate occasions before establishing a diagnosis 2, 3
- BP measurements should be repeated at the same visit using proper technique to confirm initial readings 3
- BP can vary considerably between visits and even during the same visit; only 56% of adolescents maintained the same hypertension stage across three different occasions 1
Measurement Technique Pitfalls
Proper Cuff Sizing
- Incorrect cuff size is the most common source of measurement error 3
- Cuff bladder should encircle 80-100% of arm circumference and cover approximately two-thirds of upper arm length 2, 3
- Too-small cuffs falsely elevate readings 3
Patient State
- Measurements in uncooperative or agitated children are unreliable and must be repeated when the child is calm 2
- Recent caffeine intake and anxiety can cause isolated elevated readings 1
Measurement Method
- Auscultatory measurements with mercury or calibrated aneroid sphygmomanometers remain the gold standard for diagnosis 3
- Electronic devices may provide measurements that differ from sphygmomanometer readings 3
- The normative tables are based on auscultatory measurements, while automated devices are commonly used in practice 1
Special Considerations for Neonates and Infants
Defining hypertension in neonates (0-1 year) is more challenging due to: