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Serum Ascites Albumin Gradient (SAAG)

Differentiates portal-hypertensive from non-portal-hypertensive causes of ascites.

Serum Ascites Albumin Gradient (SAAG)
Serum albumin
Ascites (peritoneal fluid) albumin
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When to use

  • Classifying the cause of new ascites once diagnostic paracentesis has been performed.

Formula

SAAG = serum albumin (g/dL) - ascites albumin (g/dL). ≥1.1 g/dL suggests portal hypertension; <1.1 g/dL suggests a non-portal-hypertensive cause.

Pearls and pitfalls

  • Approximately 97% accurate for identifying portal hypertension, more reliable than the older exudate/transudate (total protein) criteria.

References

  1. Runyon BA, et al. Ann Intern Med. 1992;117(3):215-20.