Creatinine Clearance in Pediatrics

In children, Cockcroft–Gault does not apply — it was built for adults and depends on adult weight and age relationships. The standard pediatric estimate is the bedside Schwartz equation.

Why Adult Formulas Fail in Children

A child's body composition is a moving target. Muscle mass — the source of creatinine — changes rapidly with growth, so the fixed weight-and-age coefficients that work for adults do not map onto a growing child. A toddler and a teenager with the same serum creatinine have very different kidney function. The Schwartz equation sidesteps the problem by using height as a stand-in for muscle mass, which tracks body size far more reliably across the pediatric age range. Normal creatinine values are also much lower in children, which is expected and not a sign of unusually strong kidneys.

The Bedside Schwartz Equation

It estimates eGFR (mL/min/1.73m²) from a child's height and creatinine:

eGFR = 0.413 × height (cm) ÷ serum creatinine (mg/dL)

For example, a child 120 cm tall with a creatinine of 0.5 mg/dL has an estimated eGFR of about 99 mL/min/1.73m² (0.413 × 120 ÷ 0.5). A taller child of 150 cm with the same 0.5 mg/dL estimates near 124 mL/min/1.73m², while a shorter child of 90 cm with a creatinine of 0.4 mg/dL lands around 93 mL/min/1.73m² — height moves the result as much as creatinine does.

Reading a Child's eGFR

Normal kidney function in children climbs through the first years of life and reaches the adult reference of roughly 90 mL/min/1.73m² or higher by about age two. After that, the same broad bands used in adults apply, but interpretation always accounts for the child's age and growth. A value that would be ordinary in an adult may be low for a healthy school-age child, so pediatric results are read against age-appropriate expectations rather than a single fixed cutoff. The 1.73 m² in the units is a standard adult body-surface-area normalization, which lets a small child's filtration be compared on the same scale.

Why an Accurate Height Matters

Because height sits in the numerator of the Schwartz equation, a measurement error feeds directly into the result. A child recorded as 5 cm taller than they are will have their eGFR overstated in proportion. Using a recent, carefully measured standing height (or recumbent length in infants) and a current creatinine from a standardized assay is therefore essential. Stale or estimated heights are one of the most common reasons a pediatric eGFR comes out wrong.

When the Estimate Needs Care

Bedside Schwartz assumes a standard creatinine assay and a child who is growing normally. It is less dependable at the extremes — in very young infants, in children with unusual body builds, or when creatinine is changing rapidly. In those situations a clinician may turn to a cystatin C–based estimate or a measured clearance. As always, the number guides care; it does not replace clinical judgment.

Dosing Medications in Children

Pediatric drug dosing leans on the Schwartz estimate together with the child's weight, since most pediatric doses are weight-based to begin with. When a drug is cleared by the kidneys, the eGFR guides whether the dose or interval needs adjusting for reduced function. Because a child's creatinine values are naturally low, it is easy to misread a result without the height-based context Schwartz provides — which is exactly why the adult formulas are set aside here.

See the full method on the Schwartz equation page, and learn how eGFR is interpreted.