The Cardiovascular
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Natriuretic Response Prediction Equation (NRPE)

Predicts sodium output from a 2-hour post-diuretic spot urine sample to guide loop diuretic titration.

Natriuretic Response Prediction Equation (NRPE)
Estimated GFR (e.g., CKD-EPI)
mL/min/1.73m2
Height
Weight
Serum creatinine
mg/dL
Spot urine creatinine (~2h post-diuretic)
mg/dL
Spot urine sodium (~2h post-diuretic)
mmol/L
Complete the fields above to see the result.

When to use

  • Guiding loop diuretic titration in acute decompensated heart failure using a spot urine sample obtained about 2 hours after a diuretic dose, instead of relying on fluid balance or weight.

Formula

Na output (mmol) = eGFR x (BSA/1.73) x (serum Cr / urine Cr) x 60 x 3.25 x (urine Na / 1000), where BSA is by the Du Bois formula (0.007184 x height[cm]^0.725 x weight[kg]^0.425) and 3.25 is an empiric constant converting peak instantaneous natriuresis to cumulative 6-hour output.

Pearls and pitfalls

  • Derived and validated with spot urine sodium and creatinine drawn ~1-2 hours after IV loop diuretic administration.
  • Used to drive nurse-protocolized diuretic up-titration (the Yale Diuretic Pathway) with improved decongestion in the original cohort.

References

  1. Rao VS, Ivey-Miranda JB, Cox ZL, et al. J Am Coll Cardiol. 2021;77(6):695-708.