Renal function
Urine osmolar gap
Estimate of urine NH4⁺ excretion. Helpful in non-AG metabolic acidosis.
Required inputs
- Measured urine osm (mOsm/kg)
- Urine Na (mEq/L)
- Urine K (mEq/L)
- Urine urea
- Urine glucose (optional)
Equation or source
Halperin ML. Kidney Int 1988;33:1042.