SAAG Calculation and Interpretation in Tuberculous Peritonitis

Introduction to SAAG Calculation

The SAAG is calculated by measuring both serum albumin and ascitic fluid albumin on the same day, then subtracting the ascitic fluid albumin value from the serum albumin value, as recommended by the American Association for the Study of Liver Diseases 1, 2, 3

A SAAG ≥1.1 g/dL indicates portal hypertension with approximately 97% accuracy, according to the American Association for the Study of Liver Diseases 1, 2, 3
A SAAG <1.1 g/dL indicates non-portal hypertension causes of ascites, such as tuberculous peritonitis, as stated by the European Association for the Study of the Liver 1, 4, 3

Ascitic fluid lymphocytosis is typically present in tuberculous peritonitis, as noted by the American Association for the Study of Liver Diseases 1, 2
Adenosine deaminase (ADA) >32-40 U/L has high sensitivity and specificity for tuberculous peritonitis, according to the American Association for the Study of Liver Diseases 1, 2

Severe hypoalbuminemia affects the absolute values but not the gradient interpretation of SAAG, maintaining its diagnostic accuracy, as stated by the American Association for the Study of Liver Diseases 1, 3

For suspected tuberculous peritonitis with severe hypoalbuminemia, obtain simultaneous serum and ascitic fluid albumin, calculate SAAG, and order ascitic fluid cell count with differential, total protein, LDH, and ADA, as recommended by the American Association for the Study of Liver Diseases 1, 4, 3

Ascitic fluid ADA with cut-off >32 U/L (or >27 U/L if cirrhosis present) can aid in diagnosis, according to the American Association for the Study of Liver Diseases 1, 2
Ascitic fluid acid-fast bacilli smear and culture, although with limited sensitivity, can be used for diagnosis, as noted by the American Association for the Study of Liver Diseases 1, 2
If diagnosis remains uncertain, laparoscopy with peritoneal biopsy and mycobacterial culture is the gold standard, as stated by the American Association for the Study of Liver Diseases 1, 2