Nephrology · Paediatrics

CKiD U25 eGFR calculator

Enter the published formula inputs below to calculate and interpret this score.

Clinical inputs

Age in years

years

Allowed range: 0–40 years

Only ages from 1 through 25 years are scored. Under 12 years and from 12 to under 18 use different powers of K. From 18 through 25, K is constant.

Sex

Height

Allowed range: 30–250 cm

Enter height in meters. The creatinine equation multiplies K by height and divides by creatinine.

Serum creatinine

mg/dL

Allowed range: 0.1–20 mg/dL

Enzymatic creatinine in mg/dL. The displayed result is the height/creatinine equation.

Cystatin C, if measured

mg/L

Allowed range: 0–10 mg/L

Leave blank when cystatin C was not measured. When entered in mg/L, a separate cystatin equation is shown and is not averaged with the creatinine result.

Result

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Primary source

Pierce CB et al. Age- and sex-dependent clinical equations to estimate glomerular filtration rates in children and young adults with chronic kidney disease. Kidney Int. DOI: 10.1016/j.kint.2020.10.047. PMID: 33301749. Creatinine eGFR = K × height in meters / serum creatinine in mg/dL. Male K is 39.0×1.008^(age−12) under 12 years, 39.0×1.045^(age−12) from 12 to under 18, and 50.8 from 18 through 25. Female K is 36.1×1.008^(age−12) under 12, 36.1×1.023^(age−12) from 12 to under 18, and 41.4 from 18 through 25. Cystatin eGFR = K / cystatin C in mg/L, with the Table 2 age-dependent K, and is shown only when cystatin C is entered. (2021)

Scope: Children and young adults from 1 through 25 years. Enzymatic isotope-dilution mass spectrometry creatinine. An age under 1 year or over 25 years is not scored.

Last reviewed 2026-10-16

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Professional use only

For qualified clinicians. Independently verify inputs, calculations, source guidance, and applicability before any clinical action. This calculator does not replace clinical judgment.

Source: Pierce CB et al. Age- and sex-dependent clinical equations to estimate glomerular filtration rates in children and young adults with chronic kidney disease. Kidney Int. DOI: 10.1016/j.kint.2020.10.047. PMID: 33301749. Creatinine eGFR = K × height in meters / serum creatinine in mg/dL. Male K is 39.0×1.008^(age−12) under 12 years, 39.0×1.045^(age−12) from 12 to under 18, and 50.8 from 18 through 25. Female K is 36.1×1.008^(age−12) under 12, 36.1×1.023^(age−12) from 12 to under 18, and 41.4 from 18 through 25. Cystatin eGFR = K / cystatin C in mg/L, with the Table 2 age-dependent K, and is shown only when cystatin C is entered. (2021)

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Clinical inputs

Age in yearsAccepted range: 0 to 40
Sex
Height (m)Accepted range: 0.3 to 2.5
Serum creatinine (mg/dL)Accepted range: 0.1 to 20
Cystatin C, if measured (mg/L)Accepted range: 0 to 10

Primary source

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