The serum-ascites albumin gradient (SAAG) is a calculation used in medicine to help determine the cause of ascites. The SAAG may be a better discriminant than the older method of classifying ascites fluid as a transudate versus exudate.
The formula is as follows:
SAAG = (albumin concentration of serum) - (albumin concentration of ascitic fluid).
Ideally, the two values should be measured at the same time.