calculate_urine_anion_gap: Urine Anion Gap

In cliot: Clinical Indices and Outcomes Tools

Urine Anion Gap

Description

Calculates the Urine Anion Gap (UAG) to evaluate the cause of normal anion gap metabolic acidosis. The UAG serves as a surrogate for urinary ammonium (NH4+) excretion. A negative UAG implies appropriate urinary acidification (high NH4+, often due to GI bicarbonate loss), while a positive UAG suggests a renal acidification defect (low NH4+, e.g., Renal Tubular Acidosis).

Usage

calculate_urine_anion_gap(urine_sodium, urine_potassium, urine_chloride)

Arguments

urine_sodium	Numeric. Urine Sodium concentration in mmol/L or mEq/L.
urine_potassium	Numeric. Urine Potassium concentration in mmol/L or mEq/L.
urine_chloride	Numeric. Urine Chloride concentration in mmol/L or mEq/L.

Details

The formula is:

UAG = (U_{Na} + U_{K}) - U_{Cl}

Interpretation:

• Negative Gap: Suggests GI bicarbonate loss (e.g., diarrhea).

• Positive Gap: Suggests Renal Tubular Acidosis (RTA).

Value

A list containing:

Urine_Anion_Gap	The calculated urine anion gap.
Interpretation	Diagnostic suggestion based on the gap polarity.

References

Goldstein MB, Bear R, Richardson RM, et al. The urine anion gap: a clinically useful index of ammonium excretion. Am J Med Sci. 1986;292(4):198-202. doi:10.1097/00000441-198610000-00003

Examples

# Example 1: Negative Gap (GI Loss)
# Na 40, K 20, Cl 80 -> (40+20)-80 = -20
calculate_urine_anion_gap(40, 20, 80)

# Example 2: Positive Gap (RTA)
# Na 40, K 20, Cl 50 -> (40+20)-50 = 10
calculate_urine_anion_gap(40, 20, 50)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.