Serum-Ascites Albumin Gradient
Separates ascites from portal hypertension from other causes using serum and fluid albumin.
When to use
Etiologic classification of ascites in adults after diagnostic paracentesis with contemporaneous serum albumin.
Pearls and pitfalls
- The gradient is serum albumin minus ascites albumin, both in g/dL.
- The 1.1 g/dL cutoff separates portal hypertension from other causes in the original cohort.
- The gradient does not define the specific cause of portal hypertension and does not replace fluid cytology and culture.
- Serum albumin should be measured on the same day as paracentesis to avoid misinterpretation.
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Formula
SAAG (g/dL) = serum albumin (g/dL) minus ascites albumin (g/dL).
Evidence
Prospective study of 901 paired samples that showed the gradient was superior to the exudate-transudate classification.
References
- Runyon BA, Montano AA, Akriviadis EA, Antillon MR, Irving MA, McHutchison JG. The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites. Ann Intern Med. 1992;117(3):215-220. doi:10.7326/0003-4819-117-3-215
Frequently asked questions
What is Serum-Ascites Albumin Gradient?
Separates ascites from portal hypertension from other causes using serum and fluid albumin. Etiologic classification of ascites in adults after diagnostic paracentesis with contemporaneous serum albumin.
How is the result calculated?
SAAG (g/dL) = serum albumin (g/dL) minus ascites albumin (g/dL).
How should the result be interpreted?
Prospective study of 901 paired samples that showed the gradient was superior to the exudate-transudate classification.
What are the sources?
Runyon BA, Montano AA, Akriviadis EA, Antillon MR, Irving MA, McHutchison JG. The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites. Ann Intern Med. 1992;117(3):215-220.