Serum-Ascites Albumin Gradient Calculator
Calculate the serum-ascites albumin gradient with conventional or SI units.
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Serum-ascites albumin gradient
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Paired-sample gradient; no ascites cause is assigned
Serum-ascites albumin gradient
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Normalized albumin: serum — g/dL · ascitic fluid — g/dL
About
The serum-ascites albumin gradient (SAAG) subtracts ascitic-fluid albumin from serum albumin, ideally using samples obtained at the same time. It provides physiologic information related to the pressure driving ascites, but the number alone does not establish portal hypertension or a specific cause of ascites.
Formula
Interpretation
Input units: Serum and ascitic albumin may each be entered in g/dL or g/L; both are converted to g/dL before subtraction.
Worked example: Serum albumin 3.2 g/dL and ascitic albumin 1.0 g/dL gives SAAG = 2.2 g/dL.
Applicable population: Evaluation of ascitic fluid with a paired serum albumin. A value near 1.1 g/dL has been used in studies and guidance, but this calculator does not turn that cutoff into a diagnosis.
Limitations: Samples should be obtained as close together as practical. Albumin assay variation and clinical context matter. Ascitic total protein is a separate measurement that may add different information and cannot be inferred from SAAG.
References
- Runyon BA, et al. The serum-ascites albumin gradient is superior to the exudate-transudate concept in the differential diagnosis of ascites. Ann Intern Med. 1992;117:215-220.
- Biggins SW, et al. Diagnosis, Evaluation, and Management of Ascites, SBP and Hepatorenal Syndrome: 2021 AASLD Practice Guidance. Hepatology. 2021;74:1014-1048.
FAQ
Disclaimer
Educational and informational reference only. Not intended to replace professional medical advice, diagnosis, treatment, or independent verification.