How do you interpret a serum-ascites albumin gradient (SAAG) and what does SAAG ≥1.1 g/dL indicate?

• A. SAAG <1.1 indicates portal hypertension.
• B. SAAG ≥1.1 indicates non-portal hypertension etiologies.
• C. SAAG ≥1.1 indicates portal hypertension as the cause of ascites.
• D. SAAG is not useful in evaluating ascites.

Answer: (C)

SAAG differentiates ascites caused by portal hypertension from other causes. It’s calculated as serum albumin minus ascitic fluid albumin. A SAAG of 1.1 g/dL or higher means the ascites is due to portal hypertension, typically from cirrhosis, alcoholic liver disease, or congestive heart failure. The high gradient occurs because elevated portal pressure drives fluid with relatively low protein content into the peritoneal space, yielding a transudative ascites with a large serum–ascites albumin gap. A SAAG below 1.1 g/dL points to non-portal hypertension etiologies, such as infections (e.g., tuberculous peritonitis), malignancy with exudative fluid, pancreatitis, or nephrotic syndrome–related ascites, where the ascitic fluid protein is relatively higher. This gradient helps guide the diagnostic approach and management.