Categories: Nephrology

What is the urine anion gap?

Urine AG = Urine (Na + K – Cl)

NOTE: In the setting of Bicarbonate loss, kidneys will retain Bicarbonate and excrete Ammonium (NH4). We do not measure NH4(+) directly; it is measured indirectly by measuring the negative ion (Chloride) it is secreted with to maintain electroneutrality (NH4Cl). 

In the setting of non-anion gap metabolic acidosis:

DIARRHEA

RTA

  • Urine anion gap is negative; Neg GUT tive
  • Kidneys are functioning properly and attempting to retain Bicarbonate
  • Urine anion gap is positive
  • Kidneys are not functioning properly and unable to excrete ammonium normally

 

REFERENCES

1. Cho KC. Chapter 21. Electrolyte & Acid-Base Disorders. McPhee SJ, Papadakis MA, Rabow MW, eds. CURRENT Medical Diagnosis & Treatment 2012. New York: McGraw-Hill; 2012.

Get Medical Pearls directly to your inbox every week!
Weekly posts with high yield medical knowledge, directly to your mailbox!
Dr. C Humphreys

Internal Medicine

Recent Posts

Mechanism of a Mixed Apnea

Mixed apneas are characterized by absent respiratory effort and airflow in the first section of…

12 months ago

How Does Hypothyroidism Cause Hypoventilation?

Although rare, the differential diagnosis of hypoventilation and hypercapnia respiratory failure includes hypothyroidism. It is…

12 months ago

Why is Pro-BNP/ BNP lower in Obesity?

B-type natriuretic peptide (BNP) is a hormone created in response to cardiac wall stretch due…

1 year ago

What is Peribronchovascular Distribution on CT imaging?

A common finding described on computed tomography (CT) imaging. A disease with a peribronchovascular distribution…

2 years ago

Trapped Lung vs. Lung Entrapment

Though often used synonymously; Trapped Lung and Lung Entrapment technically describe separate entities along the…

3 years ago

Cause of Pericardial Effusion in Pulmonary Hypertension: Pathogenesis

It is not clearly understood why patients with pulmonary hypertension (PH) develop pericardial effusions. However,…

3 years ago

This website uses cookies.