What does a Serum-Ascites Albumin Gradient (SAAG) of 0.9 indicate?

From the Guidelines

A Serum-Ascites Albumin Gradient (SAAG) of 0.9 g/dL indicates non-portal hypertension as the cause of ascites. This value falls below the standard cutoff of 1.1 g/dL, suggesting that the fluid accumulation in the peritoneal cavity is not related to increased pressure in the portal venous system. Instead, this low SAAG value points to other potential causes such as peritoneal carcinomatosis, tuberculosis peritonitis, pancreatic ascites, nephrotic syndrome, or protein-losing enteropathy. When evaluating a patient with a SAAG of 0.9, further diagnostic workup should focus on these non-portal hypertensive etiologies, which might include cytological examination of ascitic fluid, peritoneal biopsy, or imaging studies to identify malignancy or infection. The SAAG is calculated by subtracting the ascitic fluid albumin concentration from the serum albumin concentration, and it effectively differentiates between causes of ascites with approximately 97% accuracy, making it more useful than the traditional transudate-exudate classification 1.

Some key points to consider in the diagnosis and management of ascites with a low SAAG include:

• The SAAG is a useful tool for distinguishing between portal hypertensive and non-portal hypertensive causes of ascites 1.
• A low SAAG value suggests that the ascites is not due to portal hypertension, and other causes should be considered 1.
• Further diagnostic workup may include cytological examination of ascitic fluid, peritoneal biopsy, or imaging studies to identify malignancy or infection 1.
• The management of ascites with a low SAAG will depend on the underlying cause, and may involve treatment of the underlying condition, such as malignancy or infection 1.
• It is essential to note that a low SAAG value does not rule out the presence of portal hypertension, and other diagnostic tests may be necessary to confirm the diagnosis 1.
• The SAAG should be interpreted in the context of other clinical and laboratory findings, and a comprehensive diagnostic workup should be performed to determine the underlying cause of ascites 1.

From the Research

SAAG Interpretation

• A Serum-Ascites Albumin Gradient (SAAG) of 0.9 indicates a low SAAG, which is typically associated with non-portal hypertension etiologies, such as malignancies, tuberculous peritonitis, and nephrotic syndrome 2.
• A SAAG level of <1.1 g/dl is usually thought of as a result of nonportal hypertension etiologies 2.
• The predictive value of a low SAAG in patients with existing cirrhosis is not clear, and evaluation of a SAAG <1.1 g/dl in patients with known cirrhosis has low yield and is less likely to be helpful than that in patients without cirrhosis 2.

Differential Diagnosis

• SAAG is a useful diagnostic parameter that can be used to separate ascites of liver disease from other causes of ascites, with an efficiency of 91% 3.
• A low SAAG can be seen in hypoalbuminemia, malignancy, or an infectious process 4.
• The causes of ascites can be identified based on SAAG, with liver disease being the major cause, followed by peritoneal tuberculosis, malignancy, congestive heart failure, and nephrotic syndrome 3.

SAAG Cut-off Value

• The traditional cut-off value for SAAG is 1.1 g/dl, with a high SAAG indicating portal hypertension and a low SAAG indicating non-portal hypertension etiologies 5.
• However, a study suggested that a SAAG cut-off value of 12.50 g/L might be more reasonable in Chinese ascitic patients, with a sensitivity of 99.20%, specificity of 95.10%, and accuracy of 97.65% 6.