Pediatric Echocardiography Z‑Score Calculator
Calculate pediatric echo Z-scores using PHN/Lopez 2017 and Detroit/Pettersen 2008 reference models. Results should be interpreted within the selected model and measurement definition.
Reference models, units & interpretation
Select one pediatric echocardiography Z-score reference model first, then choose a supported structure to calculate expected size and optional measured-value Z-score from BSA.
PHN / Lopez 2017 and Detroit / Pettersen 2008 are BSA-based pediatric echo models with different measurement definitions and reference cohorts; use the same reference model, measurement definition, and BSA method consistently.
Displayed values are shown in millimeters; internal calculations may use centimeters depending on the selected model.
Pediatric Echo Z-score
Pediatric Echo Z-score Calculator
Select a reference model, choose a structure, and calculate expected size or measured-value Z-score from BSA.
Input
PHN reference range: 0.15–2.50 m². Detroit / Pettersen results are calculated for BSA ≤2.0 m²; BSA >2.0 m² is out of range.
Optional BSA from Height/Weight
Calculated BSA: —
Reference model and structure
Choose one model first. Structure options are limited to the selected model.
PHN / Lopez: Developed from healthy, non-obese pediatric subjects up to 18 years. Use caution when applying to patients outside typical pediatric body size ranges.
Z-scores and expected sizes may differ between models. Use the same model consistently for serial follow-up.
Expected size
Measured value, optional
Calculated Z-score: —
Enter a measured value to calculate Z-score.
Model notes & interpretation limits
- Select one reference model and use it consistently for serial follow-up; results should not be mixed across reference models.
- This calculator is intended for pediatric echocardiography Z-score interpretation only. Do not use these pediatric reference models for adult patients, even when the calculated BSA falls within the model’s numeric input range.
- PHN / Lopez 2017 and Detroit / Pettersen 2008 use different reference populations, measurement definitions, and regression methods, so Z-scores and expected sizes may differ between models for the same BSA value.
- The BSA formula is user-selectable when height/weight BSA calculation is used, and the resulting BSA value affects Z-score interpretation. Displayed values are in millimeters; internal calculations may use centimeters depending on the selected model.
- Z-score interpretation should consider growth stage, diagnosis, image quality, measurement technique, and serial trends.
- This calculator supports clinical assessment and education but does not replace physician judgment, echocardiography lab standards, or institutional protocols.
About this pediatric echo Z-score calculator
This pediatric echocardiography Z-score calculator estimates expected cardiac structure size from body surface area and calculates optional measured-value Z-scores. It supports PHN / Lopez 2017 and Detroit / Pettersen 2008 reference models. Users can select a model, choose a supported structure, enter a target Z-score, and view the corresponding expected size in millimeters. A measured value can also be entered to calculate a forward Z-score using the selected model.
The PHN / Lopez reference model supports 25 linear cardiac structures organized into 5 clinical groups: Heart valves (Aortic annulus, Mitral valve AP and lateral, Tricuspid valve AP and lateral, Pulmonary valve short-axis and long-axis), Aorta and aortic arch (Aortic root, Sinotubular junction, Ascending aorta, Proximal aortic arch, Distal aortic arch, Aortic isthmus), Coronary arteries (LMCA, Proximal LAD, Proximal RCA), Pulmonary arteries (Main pulmonary artery, Left pulmonary artery, Right pulmonary artery), and Left ventricular dimensions (LVEDD, LVESD, LVPWT, LVST, LVEDL endocardial, and LVEDL epicardial). The Detroit / Pettersen 2008 model supports 21 pediatric cardiac dimensions.
Use this pediatric echo Z-score calculator for BSA-adjusted Z-score review, cardiac structure size planning, PHN Lopez Z-score checks, Detroit Pettersen Z-score checks, expected size by Z-score, and measured-value Z-score education. For quick clinical context, see the Quick Reference page.
How the equations work
PHN / Lopez 2017
PHN / Lopez 2017 uses BSA-adjusted reference equations for common pediatric echocardiographic measurements. The calculator applies the selected structure’s coefficients to estimate expected size at a given BSA and target Z-score. The measured-value Z-score is calculated by comparing the user-entered measurement with the model-predicted mean and dispersion.
indexedValue = measuredNative / BSA^alpha
z = (indexedValue - Mean) / SD
targetNative = (Mean + targetZ × SD) × BSA^alpha
The original PHN reference model used Haycock BSA. Results may differ when another BSA formula is selected.
Native units and display conversion: Most PHN linear structures use centimeters (cm) natively, while coronary artery dimensions (LMCA, LAD, RCA) use millimeters (mm) natively. All user inputs and displayed expected sizes are presented in millimeters (mm) for clinical workflow convenience. Native centimeter measurements are converted to and from millimeters (1 cm = 10 mm), whereas coronary artery values are calculated directly in native millimeters without unit scaling.
Detroit / Pettersen 2008
Detroit / Pettersen 2008 uses a log-linear regression model with body surface area as the independent variable. Results are calculated for BSA ≤2.0 m²; BSA >2.0 m² is shown as out of range because extrapolation may produce implausible values. Interpret measurements within the Detroit / Pettersen definitions and limits, and keep the BSA method consistent when comparing results.
meanLn = b0 + b1 × BSA + b2 × BSA² + b3 × BSA³
z = (ln(measuredCm) - meanLn) / sqrt(MSE)
targetCm = exp(meanLn + targetZ × sqrt(MSE))
targetMm = targetCm × 10
User-entered and displayed values are in millimeters. Detroit / Pettersen calculations internally convert measured size from millimeters to centimeters before applying the logarithmic equation.
FAQ
What Z-score models are available?
This calculator supports PHN / Lopez 2017 and Detroit / Pettersen 2008 pediatric echocardiography Z-score models. Select one model before interpreting expected size or measured-value Z-score results.
Which BSA formula is used?
The built-in height/weight BSA calculator uses the formula selected in the BSA method selector. The selected Z-score reference model does not automatically determine the BSA formula. When comparing results, use the same reference model, measurement definition, and BSA method consistently.
Why can different pediatric echo Z-score calculators give different results?
Different pediatric echo Z-score calculators may use different reference populations, BSA methods, measurement definitions, and regression methods. Use one selected model, measurement definition, and BSA method consistently, and avoid mixing serial results across models.
What is a pediatric echo Z-score?
A pediatric echo Z-score describes how far a measured cardiac structure is from the expected mean for a child’s body size. A Z-score of 0 is close to the model-predicted average, while positive values are larger and negative values are smaller than expected.
What age range is appropriate for this calculator?
Pettersen 2008: 1 day to 18 years; Detroit / Pettersen results are calculated for BSA ≤2.0 m² and are not calculated when BSA >2.0 m². PHN / Lopez 2017: ≤ 18 years, healthy non-obese children. Results outside these ranges should be interpreted with caution.
Can I compare PHN and Detroit / Pettersen results directly?
They can be reviewed side by side conceptually, but they should not be treated as interchangeable. Differences may reflect model design, reference population, structure definitions, BSA value, and regression method.
Can this calculator be used for adult patients?
No. These PHN/Lopez and Detroit/Pettersen models are pediatric echocardiography reference models and should not be used to interpret adult cardiac measurements. Even if an adult patient’s BSA falls within the accepted numeric range, adult patients require adult-specific reference ranges or clinical interpretation.
What units should I enter?
Enter measured structure size in millimeters. The calculator displays expected sizes in millimeters. Some internal model equations may convert values to centimeters.
Selected references
Reference equations are implemented for educational and clinical support use. Always confirm measurement technique, anatomical definition, and selected model before applying results clinically.
- Lopez L, Colan SD, Frommelt PC, et al. Relationship of echocardiographic Z scores adjusted for body surface area to age, sex, race, and ethnicity: the Pediatric Heart Network normal echocardiogram database. Circulation: Cardiovascular Imaging. 2017.
- Pettersen MD, Du W, Skeens ME, Humes RA. Regression equations for calculation of Z scores of cardiac structures in a large cohort of healthy infants, children, and adolescents: an echocardiographic study. Journal of the American Society of Echocardiography. 2008;21:922-934.
- Lopez L, Frommelt PC, Colan SD, et al. Pediatric Heart Network Echocardiographic Z Scores: Comparison with Other Published Models. Journal of the American Society of Echocardiography. 2021;34(2):185-192.