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…

2 months ago

How Does Hypothyroidism Cause Hypoventilation?

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

2 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…

8 months ago

What is Peribronchovascular Distribution on CT imaging?

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

1 year ago

Trapped Lung vs. Lung Entrapment

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

2 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,…

2 years ago

This website uses cookies.