This version was machine-translated from German and has not been medically reviewed. The authoritative version is the German version.

• Kidney length percentiles

  Sonographic kidney length and kidney volume by age and sex as percentiles (Viteri 2025)

• eGFR (bedside Schwartz 2009)

  Estimated glomerular filtration rate from height and serum creatinine, with KDIGO categories

• eGFR by CKiD U25 (creatinine)

  Age- and sex-dependent creatinine equation for 1–25-year-olds with chronic kidney disease (Pierce 2021)

• eGFR by CKiD U25 (cystatin C)

  Cystatin C equation for 1–25-year-olds: eGFR = K / cystatin C with age- and sex-dependent K

• eGFR by CKiD U25 (creatinine + cystatin C)

  Mean of the creatinine and cystatin C estimates – the most accurate variant of the CKiD U25 equations

• FENa – fractional sodium excretion

  Prerenal (< 1 %) or intrinsic (≥ 3 %)? From sodium and creatinine in urine and serum

• FEUrea – fractional urea excretion

  More reliable than FENa under diuretics: ≤ 35 % suggests prerenal kidney failure

• FEUA – fractional uric acid excretion

  In hyponatremia: SIADH and salt loss show FEUA > 11 %; normal 4–11 %

• TRP – tubular phosphate reabsorption

  From phosphate and creatinine in urine and serum – normal approximately 85–95 %

• TmP/GFR – renal phosphate threshold

  According to Payne from TRP and serum phosphate, with reference range by age and sex (1–73 years)

• Protein/creatinine ratio in spot urine

  Normal ≤ 0.2 mg/mg (from 2 years) or ≤ 0.5 mg/mg (6–24 months); nephrotic ≥ 2 mg/mg

• Albumin/creatinine ratio (ACR)

  KDIGO albuminuria categories A1 (< 30 mg/g), A2 (30–300 mg/g), A3 (> 300 mg/g)

• Calcium/creatinine ratio in spot urine

  Hypercalciuria screening with age-specific P95 percentiles (Sargent 1993): 0.86 / 0.60 / 0.42 / 0.22 mg/mg

• Expected bladder capacity (EBC)

  ICCS formula 30 × (age + 1) ml with assessment of the maximum voided volume; Koff and Kaefer formulas for comparison

• pRIFLE – acute kidney injury in children

  Risk / Injury / Failure from the decline in estimated creatinine clearance and urine output (Akcan-Arikan 2007)

• KDIGO AKI stages

  Stage 1–3 based on creatinine rise (relative and absolute), urine output, renal replacement therapy and eGFR < 35 in children

• Urine output and fluid balance

  ml/kg/h with KDIGO oliguria stage and balance in ml, ml/kg and % of body weight

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