Ascitic Fluid For Proteins

Function of the Test

Measuring protein levels in ascitic fluid (fluid buildup in the abdomen) is a critical step in determining the underlying cause of ascites. While modern medicine often prioritizes the Serum-Ascites Albumin Gradient (SAAG), total protein concentration remains a vital diagnostic tool to differentiate between transudative and exudative processes.

Why it is Ordered

This test is performed via paracentesis when a patient presents with new-onset ascites or when there is suspicion of an infection like Spontaneous Bacterial Peritonitis (SBP). It helps clinicians narrow down the differential diagnosis for abdominal swelling. It is specifically used to:

• Distinguish Causes: Differentiate between cirrhosis, heart failure, and malignancy.
• Assess Infection Risk: Patients with very low ascitic protein (<1 g/dL) are at a significantly higher risk for developing SBP.
• Evaluate Malignancy: High protein levels often point toward inflammatory or cancerous origins.

Associated Conditions

Traditionally, ascitic fluid with a total protein level greater than 2.5 or 3.0 g/dL is classified as an 'exudate,' which is common in conditions like tuberculosis, peritoneal carcinomatosis, or Budd-Chiari syndrome. Conversely, levels below 2.5 g/dL suggest a 'transudate,' typically caused by portal hypertension or cirrhosis. When combined with other markers like LDH and glucose, this test provides a comprehensive picture of peritoneal health and the permeability of the abdominal lining.