Serum Ascites Albumin Gradient (SAAG) Calculator

Determines whether the cause of ascites is portal hypertension or rules it out.

Refer to the text below the tool for a more in-depth interpretation of the SAAG.


Serum Ascites Albumin Gradient (SAAG) determines the gradient between the serum and ascites fluid albumin to find if is caused by portal hypertension.


SAAG = Serum Albumin in g/dL – Ascites Fluid Albumin in g/dL

Interpretation

  • Due to oncotic pressure, SAAG is usually below 1.7 g/dL. SAAG values above 1.1 g/dL are consistent with portal hypertension as the etiology of ascites, with 97% accuracy. The increase in hydrostatic pressure determines fluid to leave circulation and enter in the peritoneal space, creating the ascites fluid, while albumin molecules remain in the circulatory system.
  • SAAG values below 1.1 g/dL rule out increased portal pressure as ascites cause. Some conditions manifesting with low SAAG are tuberculosis, infections, serositis, some peritoneal carcinomas, pulmonary infarcts or the nephrotic syndrome.

Serum Albumin
Ascites Fluid Albumin
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About SAAG and its interpretation

Serum Ascites Albumin Gradient (SAAG) determines the gradient between the serum and ascites fluid albumin to differentiate whether ascites is caused by portal hypertension or not.

  • SAAG = Serum Albumin in g/dL – Ascites Fluid Albumin in g/dL

Serum albumin makes out more than 50% of total serum protein and helps transport hormones, vitamins and drugs throughout the body, also contributing to the oncotic pressure. Hypoalbuminemia is caused by liver disease, nephrotic syndrome or hemodilution, amongst others. Hyperalbuminemia is usually encountered in acutely dehydrated patients and those with high protein intake from diet.

Aside from albumin, ascetic fluid may be checked for: LDH, glucose, triglycerides, amylase, pH, gram stain (monomicrobial and polymicrobial) and cytology.

LDH values above 225 U/L indicate exudate while values below 225 U/L indicate transudate. Compared such methods that classify the ascites fluid in transudate or exudate, the SAAG is considered more accurate.

Interpretation

  • The current indication is that SAAG values above 1.1 g/dL are consistent with portal hypertension as the etiology of ascites, with 97% accuracy. The mechanism is simple and can be explained as follows: the increase in hydrostatic pressure determines fluid to leave circulation and enter in the peritoneal space, creating the ascites fluid, while albumin remains in the serum, in circulation.
  • SAAG values below 1.1 g/dL indicate that there is a different cause of ascites and that it is not associated with increased portal pressure.
High SAAG values (>1.1 g/dL) Low SAAG values (<1.1 g/dL)
Portal hypertension Infections Pulmonary infarcts
Heart failure Tuberculosis Serositis
Budd-Chiari syndrome Nephrotic syndrome Peritoneal carcinoma
 

References

Uddin MS, Hoque MI, Islam MB, Uddin MK, Haq I, Mondol G, Tariquzzaman M. Serum-ascites albumin gradient in differential diagnosis of ascites. Mymensingh Med J. 2013; 22(4):748-54.

Ginès P, Cárdenas A, Arroyo V, Rodés J. Management of cirrhosis and ascites. N Engl J Med. 2004; 350(16):1646-54.

Akriviadis EA, Kapnias D, Hadjigavriel M, Mitsiou A, Goulis J. Serum/ascites albumin gradient: its value as a rational approach to the differential diagnosis of ascites. Scand J Gastroenterol. 1996; 31(8):814-7.


Specialty: Hepatology

Abbreviation: SAAG

Article By: Denise Nedea

Published On: June 17, 2020

Last Checked: June 17, 2020

Next Review: June 17, 2025