The SAAG has replaced the old transudate/exudate classification of ascites because it predicts portal hypertension much more accurately. Both samples should be taken on the same day.
How to use the SAAG Calculator
- Serum albumin
- Ascitic fluid albumin
- Ascitic total protein (optional)
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter serum and ascitic albumin measured the same day. The calculator subtracts them; ascitic total protein helps distinguish cirrhosis (< 2.5 g/dL) from heart failure (≥ 2.5 g/dL) when SAAG is high.
Tips
- Use results from the same fasting state the formula expects (most lipid formulas assume fasting).
- Check the units on your lab report before entering values.
- Discuss treatment targets with your clinician – they depend on your overall risk.
- Repeat abnormal results; a single value can be misleading.
Common mistakes to avoid
- Using Friedewald LDL when triglycerides are above 400 mg/dL.
- Mixing mg/dL and mmol/L values in one calculation.
- Ignoring other risk factors such as smoking and blood pressure.
Inputs explained
| Field | What to enter |
|---|---|
| Serum albumin | Units: g/dL, g/L |
| Ascitic fluid albumin | Units: g/dL, g/L |
| Ascitic total protein (optional) | Units: g/dL, g/L |
Example values
How the main result changes when Serum albumin changes and everything else stays at the example values above:
| Serum albumin (g/dL) | SAAG (g/dL) |
|---|---|
| 1.6 | 0.6 |
| 2.4 | 1.4 |
| 3.2 | 2.2 |
| 4 | 3 |
| 4.8 | 3.8 |
| 6.4 | 5.4 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
SAAG = serum albumin − ascites albumin (g/dL)
≥ 1.1 g/dL: portal hypertension (about 97% accurate)
< 1.1 g/dL: non-portal causes
Worked example
Inputs — Serum albumin: 3.2 g/dL; Ascitic fluid albumin: 1 g/dL; Ascitic total protein (optional): 0 g/dL.
Results — SAAG = 2.2 g/dL; Likely group of causes = Portal hypertension (cirrhosis, heart failure, Budd–Chiari).
Key terms
- Ascites
- Fluid in the abdominal cavity.
- Portal hypertension
- High pressure in the portal vein, usually from cirrhosis.
Frequently asked questions
What does a SAAG of 1.1 or more mean?
Portal hypertension is the likely cause of the ascites.
Do the samples need to be taken together?
Yes – on the same day, ideally within hours.
Can SAAG be wrong?
Very low serum albumin or hyperglobulinaemia can affect it.