This Serum Ascites Albumin Gradient (SAAG) calculator determines the gradient between the circulatory and ascetic fluid albumin to find if is caused by portal hypertension. There is in depth information below the form on the albumin concentrations and what the gradient results mean.
How does this Serum Ascites Albumin Gradient (SAAG) calculator work?
This health tool analyzes the albumin gradient between serum and ascites fluid and provides information on whether portal hypertension is the cause of ascites or not. This determination can also be used to diagnose or rule out portal hypertension.
Compared to other methods that classify the ascites fluid in transudate or exudate, the SAAG is considered more accurate.
There are three pieces of information required by the SAAG calculator:
■ Serum concentration of albumin – measured in g/dL or g/L. This represents around 50% of the protein in the blood and is produced by the liver. It transports hormones and fatty acids and contributes to the pressure balance. Normal values are between 3.5 and 5 g/dL.
˗ High levels of albumin are consistent with hyperalbuminemia, a condition usually met in acutely dehydrated patients and high protein diets.
■ Albumin concentration in ascites fluid – measured in g/dL or g/L.
■ The measurement unit for the display of SAAG. Due to oncotic pressure, SAAG is usually below 1.7 g/dL.
The gradient is calculated as the difference between serum albumin and the albumin in the ascites fluid. The recommendation is that both parameters to be measured at the same time.
The current indication is that SAAG values above 1.1 g/dL are consistent with portal hypertension as the etiology of ascites, with 97% accuracy. The increase in hydrostatic pressure determines fluid to leave circulation and enter in the peritoneal space, creating the ascites fluid, while albumin molecules remain in the circulatory system.
Other conditions in which the ascites albumin gradient is disturbed are heart failure or the Budd-Chiari syndrome.
Gradients below 1.1 g/dL indicate that the cause of ascites is not associated with increased portal pressure. Some conditions manifesting with low SAAG are tuberculosis, infections, serositis, some peritoneal carcinomas, pulmonary infarcts or the nephrotic syndrome.
Other investigations applicable to ascetic fluid include: LDH, glucose, triglycerides, amylase, pH, gram stain (monomicrobial and polymicrobial) and cytology. LDH values above 225 U/L indicate exudate while values below 225 U/L indicate transudate.
The management of the ascetic fluid starts with the diagnosis of the cause, the application of treatment for the cause and drain for symptomatic relief.
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