Nephrology Question 7

In a patient with non-anion gap metabolic acidosis, calculating the urine anion gap can help differentiate between diarrhea and renal tubular acidosis (RTA) as the etiology.What is the urine anion gap and how is it calculated?
In the following case, please determine if the patient has a non-anion gap metabolic acidosis due to diarrhea or RTA:A 24 year old male dancer comes to attention due to a low serum bicarbonate on routine blood work. Additional results include:
Serum:
Na: 140 meq/L
K: 3 meq/L
HCO₃: 14 meq/L
Cl: 116 meq/L

Urine:
Na: 50 meq/L
K: 30 meq/L
Cl: 40 meq/L

Subscribe to Pearls