Pediatric Blood Product Worksheet
Estimate pediatric blood-product volumes for pRBCs, platelets, FFP, cryoprecipitate, and whole blood, with blood-volume context and reference infusion rates.
Pediatric GFR Calculator
Estimate glomerular filtration rate in children using Schwartz, Counahan-Barratt, and CKiD formulas. Includes CKD staging and age-specific normal ranges.
⚕️ Clinical Disclaimer: eGFR estimates are screening tools and do not replace measured GFR. Clinical correlation and lab confirmation are essential.
mg/dL
cm
years
Optional — for CKiD combined formula
mg/L
Optional — for CKiD combined formula
mg/dL
Estimated GFR⧉
90.9 mL/min/1.73m²
Updated Schwartz (2009)
CKD Stage⧉
G1 — Normal
KDIGO staging context
Normal Range (Age)⧉
90-130 mL/min/1.73m²
For age 8 years
CKiD Combined eGFR⧉
82.4 mL/min/1.73m²
Uses creatinine, cystatin C, BUN, height, and sex
BUN/Cr Ratio⧉
24.0
Higher values can accompany prerenal patterns
Height/Cr Index⧉
220.0
Higher values suggest better kidney function
CKD Staging Reference
| Stage | GFR Range | Description | Typical follow-up context |
|---|---|---|---|
| ● G1 | ≥90 | Normal or High | Often rechecked if risk factors are present |
| ● G2 | 60-89 | Mildly Decreased | Repeat and interpret with urine findings |
| ● G3a | 45-59 | Mild-Moderate Decrease | Closer follow-up is often warranted |
| ● G3b | 30-44 | Moderate-Severe Decrease | Specialist follow-up is common |
| ● G4 | 15-29 | Severely Decreased | Advanced CKD planning is often needed |
| ● G5 | <15 | Kidney Failure | Kidney replacement therapy may need discussion |
GFR Visual Assessment
Patient GFR
91
015306090130+
Planning notes, formulas, and examples
About the Pediatric GFR Calculator
Estimating glomerular filtration rate (GFR) in children requires formulas that account for growth, body size, and changing creatinine production. Adult equations such as CKD-EPI and MDRD are not designed for that setting.
The Pediatric GFR Calculator includes the Updated Schwartz equation, the classic Schwartz formula, the Counahan-Barratt equation, and the CKiD combined formula when cystatin C and BUN are available. That gives you a quick way to compare the common pediatric estimates side by side.
It also maps the result to KDIGO CKD stages and shows age-aware normal ranges, which makes the number easier to interpret in clinical context.
When This Page Helps
Pediatric kidney function is hard to estimate from creatinine alone because body size and muscle mass change quickly with age. The calculator makes it easier to compare the most common formulas without doing each calculation by hand.
Seeing the estimated GFR alongside CKD staging and an age-aware reference range helps put the result into a more useful clinical frame.
How to Use the Inputs
- Select the GFR formula you want to compare first; Updated Schwartz is the most common modern starting point.
- Enter the serum creatinine in mg/dL.
- Enter the patient height in centimeters.
- Enter the patient age and select sex.
- Optionally enter cystatin C and BUN for the CKiD combined formula.
- Review the estimated GFR, CKD stage, and normal range.
- Compare against the CKD staging table and visual GFR gauge.
Formula used
Updated Schwartz (2009): eGFR = 0.413 × Height (cm) / Serum Creatinine (mg/dL)
Classic Schwartz: eGFR = k × Height (cm) / Serum Creatinine (mg/dL)
k = 0.33 (preterm), 0.45 (term infant), 0.55 (child/adolescent F), 0.70 (adolescent M)
Counahan-Barratt: eGFR = 0.43 × Height (cm) / Serum Creatinine (mg/dL)Example Calculation
Result: 90.9 mL/min/1.73m²
Using Updated Schwartz: 0.413 × 110 cm / 0.5 mg/dL = 90.9 mL/min/1.73m², which falls in the G1 (normal) CKD stage for an 8-year-old.
Tips & Best Practices
- Always verify that your lab uses an IDMS-traceable creatinine assay before selecting the Schwartz formula version.
- In malnourished or very muscular children, cystatin C-based formulas may be more accurate than creatinine-based ones.
- Serial measurements trending over time are more valuable than any single GFR estimate.
- GFR in neonates changes rapidly in the first weeks of life — use age-specific neonatal references.
- Many renally cleared medications need closer review once GFR declines, but the exact dosing threshold depends on the drug and the clinical setting.
- The Schwartz formula is validated for children aged 1-16; use with caution outside this range.
Evolution of Pediatric GFR Estimation
The original Schwartz formula (1976) used height and serum creatinine with an age/sex-specific constant (k) to estimate GFR. However, the k-values were derived using the Jaffé creatinine assay, which measures higher creatinine levels than modern enzymatic (IDMS-standardized) assays. Using the classic formula with current assays systematically overestimates GFR.
The Updated Schwartz equation (2009, also called the Bedside Schwartz) was derived from the CKiD cohort using IDMS-standardized creatinine. It uses a single k-value of 0.413 for all children aged 1-16, simplifying calculations while improving accuracy. It is now one of the most commonly used pediatric creatinine-based eGFR starting points.
The CKiD Combined Formula
The Chronic Kidney Disease in Children (CKiD) study developed a combined formula incorporating creatinine, cystatin C, BUN, height, and sex. This multi-marker approach provides better accuracy than any single-marker formula, particularly in children with GFR 15-75 mL/min/1.73m².
Cystatin C adds independent information because its production is relatively constant regardless of diet, muscle mass, or age after infancy. Combining markers reduces the impact of individual assay variability and biological confounders.
Clinical Decision-Making with Pediatric GFR
Pediatric CKD management follows KDIGO staging (G1-G5), but interpretation must account for age-specific normal values. A GFR of 70 mL/min/1.73m² is normal for a 6-month-old but represents CKD stage 2 in a 5-year-old. Progressive decline in GFR over serial measurements is often more clinically significant than any single estimate.
Sources & Methodology
Last updated:
Methodology
This worksheet applies the bedside Schwartz and related pediatric kidney-function equations to estimate GFR from creatinine and growth data. It is a comparison aid, not a substitute for full nephrology review or trend interpretation.
Sources
- A simple estimate of GFR in children and adolescents (Schwartz et al.) — Original bedside Schwartz equation reference.
- Chronic Kidney Disease in Children (CKiD) (National Kidney Foundation) — Pediatric kidney-function reference and equation context.
Frequently Asked Questions
The 2009 update was validated against iohexol-measured GFR using standardized (IDMS-traceable) creatinine assays, making it more accurate with modern lab methods. The classic formula overestimates GFR with current assays.
GFR matures with age. Term newborns have a GFR of ~40 mL/min/1.73m², which increases to adult levels (~90-130) by age 2. Premature infants start even lower.
Adult formulas may be reasonable in some post-pubertal adolescents, but pediatric equations remain the safer default through childhood and adolescence because creatinine generation and body composition are still changing.
Cystatin C is a protein freely filtered by the glomerulus that is less affected by muscle mass than creatinine. Including it in the CKiD combined formula improves accuracy, especially in children with abnormal muscle mass.
Refer when eGFR is persistently below 60 mL/min/1.73m² (CKD stage 3+), when there is significant proteinuria, or when GFR is declining over serial measurements.
Height serves as a proxy for muscle mass (and thus creatinine generation) in pediatric formulas. Taller children generate more creatinine, so a higher creatinine in a tall child does not necessarily indicate worse kidney function.
More in this topic
Creatinine Clearance Calculator
Calculate creatinine clearance using the Cockcroft-Gault equation. Estimate kidney function for drug dosing and renal assessment.
eGFR Calculator
Calculate estimated glomerular filtration rate using the CKD-EPI race-free creatinine equation. Review chronic kidney disease stage bands and kidney-function context.