Pediatric GFR Calculator - Glomerular Filtration Rate

Estimating kidney function in growing children is fundamentally different from adults because body composition, muscle mass, and metabolic rates change rapidly with age and stature. This calculator employs specialized pediatric formulas that factor in height, serum creatinine (Scr), and cystatin C (CysC). For instance, standard bedside formulas relate height in centimeters directly to serum creatinine using an empirical constant, while advanced multi-marker equations incorporate blood urea nitrogen and cystatin C to yield a more robust assessment of glomerular filtration.

Consider a 10-year-old child with a standing height of 135 cm, a serum creatinine (Scr) level of 0.6 mg/dL, and a cystatin C (CysC) level of 0.9 mg/L. Using the standard height-to-creatinine estimating formula (GFR1 = 41.3 multiplied by the ratio of height to serum creatinine), we first calculate 135 divided by 0.6, which equals 225. Multiplying 225 by the constant 41.3 yields an estimated GFR of approximately 92.9 mL/min/1.73m², placing the child's filtration function within a typical healthy reference range.

Ensure that height measurements are precise and taken without shoes immediately before lab draws, as minor stature errors can noticeably shift estimated output values. Always verify that laboratory units match the required input parameters (e.g., mg/dL for creatinine and mg/L for cystatin C) to avoid calculation skewing. Remember that eGFR tools provide screening estimates rather than definitive diagnoses, meaning any abnormal findings should always be reviewed by a qualified pediatric nephrologist.