Mindray ePM 12MC - Page 218

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23.7.3 Calculated Parameters and Formulas for Renal Calculations
*: BUN/Cr is a ratio at mol unit system.
Calculated Parameters Label Unit Formula
urine sodium excretion URNaEx mmol/24 hrs URNaEx (mmol/24 hrs) = Urine (ml/24 hrs) ×
URNa (mmol/L)/1000
urine potassium excretion URKEx mmol/24 hrs URKEx (mmol/24 hrs) = Urine (ml/24 hrs) × URK
(mmol/L)/1000
sodium potassium ratio Na/K % Na/K (%) = 100 × URNa (mmol/L)/URK (mmol/L)
clearance of sodium CNa ml/24 hrs CNa (ml/24 hrs) = URNa (mmol/L) × Urine (ml/24
hrs)/SerNa (mmol/L)
creatinine clearance rate Clcr ml/min Clcr (ml/min) = Ucr (mol/L) × Urine (ml/24 hrs)/
[Cr (mol/L) × (BSA (m
2
)/1.73) × 1440]
fractional excretion of
sodium
FENa % FENa (%) = 100 × URNa (mmol/L) × Cr (mol/L)/
[SerNa (mmol/L) × Ucr (mol/L)]
osmolar clearance Cosm ml/min Cosm (ml/min) = Uosm (mOsm/kgH
2
O) × Urine
(ml/24 hrs)/(Posm (mOsm/kgH
2
O) × 1440)
free water clearance CH2O ml/hr CH2O (ml/hr) = Urine (ml/24 hrs) × [1 - Uosm
(mOsm/kgH
2
O)/Posm (mOsm/kgH
2
O)]/24
urine to plasma
osmolality ratio
U/P osm
None
U/P osm = Uosm (mOsm/kgH
2
O)/Posm (mOsm/
kgH
2
O)
blood urea nitrogen
creatinine ratio
BUN/Cr*
Mmol/L
BUN/Cr = 1000 × BUN (mmol/L)/Cr (mol/L)
urine-serum creatinine
ratio
U/Cr None U/Cr (mmol/L) = Ucr (mol/L)/Cr (mol/L)