American Board of Internal Medicine (ABIM) Certification Practice Exam

What does a Serum-Ascites Albumin Gradient (SAAG) of less than 1.1 g/dL indicate?

1. Cardiac ascites

2. Nephrotic syndrome or myxedema

3. Cirrhosis

4. Infections or malignancy

The correct answer is: Nephrotic syndrome or myxedema

A Serum-Ascites Albumin Gradient (SAAG) of less than 1.1 g/dL is indicative of an ascitic fluid that is not primarily due to portal hypertension, which is often associated with conditions like cirrhosis or cardiac ascites. Instead, a low SAAG typically points toward other underlying issues. In the context of the conditions listed, a SAAG under 1.1 g/dL is most commonly seen in nephrotic syndrome or myxedema. When nephrotic syndrome is present, the protein loss leads to a decreased concentration of albumin in the blood, which can result in ascites formation. Myxedema, related to severe hypothyroidism, can also lead to fluid accumulation in tissues, including the peritoneal cavity. In contrast, conditions such as cirrhosis, cardiac ascites, or malignancy generally result in a higher SAAG due to the portal pressure effects or direct influences on albumin levels in the serum relative to the ascitic fluid. Therefore, recognizing that a SAAG of less than 1.1 g/dL often points toward diagnoses such as nephrotic syndrome or myxedema helps in guiding further diagnostic and therapeutic strategies.