From the Guidelines
Saag (serum-ascites albumin gradient) is a valuable diagnostic tool for determining the cause of ascites, with a high gradient (≥1.1 g/dL) indicating portal hypertension and a low gradient (<1.1 g/dL) suggesting non-portal hypertension causes. To calculate Saag, subtract the ascitic fluid albumin from the serum albumin, obtained from samples drawn at the same time. Portal hypertension causes include cirrhosis, alcoholic hepatitis, and heart failure, while low gradient causes include peritoneal carcinomatosis, tuberculosis, and pancreatitis. Additionally, the total protein content in ascitic fluid provides complementary diagnostic information. High protein ascites (>2.5 g/dL) with high Saag suggests cardiac ascites or early cirrhosis, while high protein with low Saag points to tuberculosis or malignancy. Low protein ascites (<2.5 g/dL) with high Saag typically indicates advanced cirrhosis. This combined approach of assessing both Saag and fluid protein helps clinicians narrow down differential diagnoses and guide appropriate treatment strategies for patients with ascites, as recommended by the most recent guidelines 1.
Key Points
- The initial ascitic fluid analysis should include total protein concentration and calculation of the serum ascites albumin gradient (SAAG) 1.
- A diagnostic paracentesis is recommended in all patients with new-onset ascites, and the ascitic fluid should be analyzed for protein and white cell count 2.
- The total protein content in ascitic fluid provides complementary diagnostic information to Saag, helping to differentiate between various causes of ascites 3, 4.
- The management of ascites in cirrhosis involves a combination of medical treatment, including diuretics and salt restriction, and may require repeated paracentesis or other interventions in refractory cases 5, 2.
Diagnostic Approach
The diagnostic approach to ascites should include the calculation of Saag and the measurement of total protein content in ascitic fluid, as these provide valuable information for determining the cause of ascites and guiding treatment. The most recent guidelines recommend a diagnostic paracentesis in all patients with new-onset ascites, with analysis of ascitic fluid for protein and white cell count 1, 2. This approach helps to identify patients with portal hypertension and those with non-portal hypertension causes of ascites, and guides the selection of appropriate treatment strategies.
Treatment Strategies
The treatment of ascites in cirrhosis involves a combination of medical treatment, including diuretics and salt restriction, and may require repeated paracentesis or other interventions in refractory cases. The management of ascites should be guided by the results of diagnostic tests, including Saag and total protein content in ascitic fluid, and should take into account the underlying cause of ascites and the presence of any complications. The most recent guidelines recommend a stepped approach to the management of ascites, with increasing intensity of treatment as needed to control symptoms and prevent complications 5, 2.
From the Research
Saag and Fluid Protein
- The relationship between dietary protein intake and fluid balance has been studied in various contexts, including endurance athletes and individuals with specific dietary needs 6, 7.
- Research suggests that high protein intake can have minimal effects on fluid status, with one study finding that fluid intake and fluid balance were unaffected by high protein diets 6.
- However, other studies have found that certain types of protein, such as whey protein, can promote fluid balance and endurance capacity in warm and humid environments 7.
- The role of protein in fluid balance is complex and may involve various mechanisms, including the regulation of serum electrolytes and proteins 8.
- In dialysis patients, fluid overload and tissue sodium accumulation can contribute to protein-energy malnutrition, highlighting the importance of managing sodium and fluid balance in this population 9.
- Endurance athletes may require higher protein intakes to support recovery and training adaptation, with some studies suggesting a daily protein intake of 1.8-2.0 g/kg body mass 10.