Ascites Albumin Gradient
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Serum Albumin
unit g/L g/dL
Ascites Albumin
unit g/L g/dL
R e s u l t s
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SAAG
 
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Ascites Albumin Gradient

Ascites is the abnormal accumulation of fluid inside the peritoneal cavity. This is a common clinical condition that has multiple possible causes; with the most common being chronic liver disease.

The serum-ascites albumin gradient (SAAG) helps in determination of the cause of ascites. The SAAG probably discriminates better than older measures for cause of ascites (transudate versus exudate).

According to a 1992 study by Runyon, et al. with subsequent validation in smaller trials, SAAG had 97% accuracy and can provide a rational clinical approach to the work-up of ascites.

The serum ascites albumin gradient (SAAG) is calculated by subtracting the albumin concentration of the ascitic fluid from the albumin concentration of a serum specimen obtained on the same day.

The formula used is:

  • SAAG (g/dL) = Serum Albumin - Ascites Albumin

Note: Specimen should be obtained on the same day. If numbers do not agree with the clinical scenario, the test should be repeated.

Interpretation:

  • A SAAG>=1.1 suggests presence of portal hypertension in patients with a transudative ascites.
  • A SAAG<1.1 suggests absence of significant portal hypertension in patients with exudate ascites.

The classification of types of ascites according to the level of SAAG (97% accuracy was obtained using SAAG = 1.1g/dL as cut-off)

>=1.1g/dL <1.1g/dL
Cirrhosis Peritoneal carcinomatosis
Alcoholic hepatitis Peritoneal TB
CHF Pancreatitis
Massive hepatic metastases Serositis
Vascular occlusion Nephrotic syndrome
Fatty liver disease of pregnancy Bowel obstruction / infarction / perforation
Myxedema

References:

  1. Das B, Acharya U, Purohit A. Comparative utility of sero ascites albumin gradient and ascitic fluid total protein for differential diagnosis of ascites. Indian Pediatr . 1998;35(6):542-5.
  2. Runyon BA, Montano AA, Akriviadis EA, et al. The serumascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites. Ann Intern Med. 1992;117(3):215-20.