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Urinary Sodium Plus Potassium Minus Chloride

Use the same urine specimen and matching concentration units.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Health results are educational estimates, not a diagnosis or treatment recommendation. A qualified clinician can interpret measurements in the context of your health.

Formula and method

Urinary sodium 40, potassium 20 and chloride 80 mmol/L give −20 mmol/L.

Urine anion gap = urine sodium + urine potassium − urine chloride.

Worked example

Enter these known values and leave the other values blank.

Urine sodium (mmol/L)
40 mEq/L
Urine potassium (mmol/L)
20 mEq/L
Urine chloride (mmol/L)
80 mEq/L
Urine anion gap (mmol/L)
-20 mEq/L

Assumptions and limitations

  • Use the same urine specimen and matching concentration units. For these monovalent ions mmol/L and mEq/L are numerically equal. Positive and negative differences are allowed; unmeasured urinary ions can limit clinical interpretation.
  • Arithmetic inverses use independent observations. Clear the unknown control before entering the remaining measurements.
  • This measurement calculation does not determine a diagnosis or treatment.

Common questions

How is this result calculated?

Urine anion gap = urine sodium + urine potassium − urine chloride.

Which measurements and units should I use?

Use the same urine specimen and matching concentration units. For these monovalent ions mmol/L and mEq/L are numerically equal. Positive and negative differences are allowed; unmeasured urinary ions can limit clinical interpretation.

References

Bookify adds independently reviewed bounds for urine-anion-gap: Na >= 0; K >= 0; Cl >= 0.

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