Serum-Ascites Albumin Gradient – SAAG Calculator
In medicine, the condition of excessive fluid accumulation in the abdominal cavity of our body, that is, in the peritoneal cavity, is called ‘Ascites’ . It is also commonly called ‘Mahodaram’ in rural areas. It is not a disease, but a symptom of various serious diseases. The patient may experience abdominal swelling, shortness of breath, and difficulty walking as a result.
Once the patient is diagnosed with ascites, the most important thing is to find out the real cause. It can be caused by anything from liver diseases to cancer. Let’s take a detailed look at the most accurate methods used by modern medicine to diagnose this condition, especially the ‘SAAG’ test.
What is ascites?
Simply put, ascites is the accumulation of water-like fluid between the layers of the abdomen. Women typically have about 20 milliliters of fluid during their menstrual cycle, but men have much less . Any condition that increases this amount can be considered as ascites.
This should not be considered a minor problem. The appearance of ascites in people with liver diseases such as cirrhosis is a sign that the disease has progressed to a serious stage (Decompensated Cirrhosis). Once this occurs, the mortality rate is likely to increase from 15% to 44% if proper treatment is not received . Therefore, if you notice a swollen abdomen, you should seek medical help immediately.
The main causes of ascites
There are many causes of ascites. The main ones are as follows:
Liver Cirrhosis
In the United States and Europe, about 80 percent of ascites cases are caused by liver cirrhosis . This is a condition in which the liver shrinks due to alcoholism or hepatitis infection. This blocks blood flow to the liver and causes a condition called ‘Portal Hypertension’. This is the main cause of fluid filling the abdomen.
Cancerous diseases (Malignancy)
Cancer is the culprit in about 10% of cases . Cancers that affect the abdominal organs, such as ovarian cancer and stomach cancer, can cause fluid to accumulate in the peritoneum when they spread. This is called malignant ascites.
Heart Disease (Heart Failure)
When the heart fails, especially when the right ventricle of the heart is unable to pump blood, pressure builds up in the veins, which can affect the liver and abdomen, causing ascites. This occurs in about 3% of cases .
Old methods and new changes in diagnosis
In the past, doctors relied on the amount of protein in the fluid (Ascitic Fluid Total Protein – AFTP) to diagnose the cause of ascites. Based on this, the fluid was classified into two types:
1. Transudate: Protein-poor fluid.
2. Exudate: Protein-rich fluid (more than 2.5 g/dL).
Transudate vs Exudate – Disadvantages of the Old Method
This old method had a major flaw. It often gave false positives. For example, high protein is often seen in cardiac ascites, which is caused by heart disease. According to the old method, this is considered an ‘exudate’ and can be mistaken for cancer or infection. Similarly, 20% of patients with cirrhosis have high protein. Therefore, diagnosing the disease based solely on protein is now considered an outdated method .
SAAG – A revolution in diagnostics
SAAG (Serum-Ascites Albumin Gradient) is a new and accurate test that addresses the shortcomings of older methods . It was founded in the 1990s by Dr. Runyon . Today, it is the gold standard method accepted by hepatologists worldwide.
What is SAAG?
SAAG is the number obtained when we subtract the amount of albumin in the abdominal fluid (ascitic fluid albumin) from the amount of albumin in our blood (Serum Albumin).
How is SAAG calculated?
SAAG = Serum Albumin − Ascitic Fluid Albumin . One thing to note here is that the blood and ascitic fluid should be tested on the same day. Only then will the results be accurate .
What does high SAAG (High SAAG > 1.1 g/dL) indicate?
If the SAAG value is 1.1 g/dL (or 11 g/L) or higher, it means that the patient has ‘Portal Hypertension’ . This can be said with 97% accuracy.
Portal hypertension
This is a condition in which blood pressure increases in the portal vein, the main blood vessel to the liver. If SAAG is greater than 1.1, the following diseases may be suspected:
• Liver Cirrhosis .
• Alcoholic Hepatitis.
• Heart Failure.
• Liver metastasis (cancer that has spread throughout the liver) .
How to identify cirrhosis and heart disease? (Total Protein Role)
This is where the old ‘Total Protein’ test comes in handy again. If the SAAG is greater than 1.1 but the protein in the ascitic fluid is less than 2.5 g/dL, it is likely cirrhosis . Conversely, if the SAAG is greater than 1.1 and the protein is greater than 2.5 g/dL, it is likely cardiac ascites .
What does low SAAG (Low SAAG < 1.1 g/dL) indicate?
If SAAG is less than 1.1 g/dL, it means that portal hypertension is not the culprit. This is called ‘non-portal hypertensive ascites’ . The main causes of this are as follows:
Peritoneal Carcinomatosis
This is a condition in which cancer spreads to the peritoneum, the lining of the abdomen. Cancer can spread to organs like the ovaries, stomach, and pancreas in this way. In such cases, SAAG will be low .
Tuberculous Peritonitis (TB Peritonitis)
Tuberculosis (TB) is a major cause of ascites in developing countries like India. People with abdominal TB may also have a SAAG value below 1.1 .
Additionally, SAAG is also low in diseases such as nephrotic syndrome and pancreatitis .
Ascitic Fluid Analysis: Other Factors to Consider
It is not enough to look at SAAG alone, some other factors need to be examined for an accurate diagnosis.
Ascitic Fluid Total Protein (AFTP)
As mentioned earlier, it helps to differentiate between cirrhosis and heart disease. It can also help predict the risk of infection. If the protein is less than 1.5 g/dL, there is a higher risk of infection in the abdominal fluid (Spontaneous Bacterial Peritonitis) .
Cell Count and Differential
Regardless of the type of ascites, it is essential to check the cell count. The white blood cell (WBC) count is used to determine whether there is an infection.
Infection can be identified: Spontaneous bacterial peritonitis (SBP)
SBP is a serious infection seen in patients with cirrhosis. If the number of neutrophils (PMN) in the abdominal fluid is more than 250/mm³, the patient can be confirmed to have SBP . Symptoms such as fever, abdominal pain, and fainting may be seen with this. However, sometimes no symptoms may be seen externally. Therefore, this test should be done for all cirrhosis patients who come to the hospital with ascites .
Importance of ADA test to identify tuberculosis (TB)
ADA (Adenosine Deaminase) test is the easiest and most cost-effective way to detect peritoneal tuberculosis . If the level of ADA in the ascitic fluid is more than 36-40 IU/L, it is highly likely to be TB .
In TB patients, lymphocytes are usually more abundant in the fluid. In addition, high protein and low SAAG are symptoms of TB .
Methods for detecting cancers
If cancer is suspected as the cause of ascites, the following tests may be helpful:
Cytology and Tumor Markers
Cytology is the microscopic examination of cells in the fluid. It can detect cancer cells with up to 96.7% accuracy in people with peritoneal carcinomatosis .
In addition, it is also useful to check tumor markers (CEA, CA 125, CA 19-9) in the blood and fluids. For example, CEA (Carcinoembryonic Antigen) indicates colon cancer, while CA 125 indicates ovarian cancer . But remember, people with cirrhosis and T.B. are likely to have elevated CA 125, so it cannot be confirmed that cancer is present based on this alone .
The role of the cholesterol gradient (SACG)
Cholesterol levels in ascitic fluid are higher in cancer patients. Some studies suggest that Serum Ascites Cholesterol Gradient (SACG) is better than SAAG in identifying malignant ascites . If cholesterol in ascitic fluid is more than 70 mg/dL, the probability of cancer is 96% .
Paracentesis: A simple test
Paracentesis is a procedure that involves withdrawing fluid from the abdomen and examining it. It is a very safe procedure.
Advantages of the ultrasound-guided method
In the past, doctors would feel around for fluid to find it. But today, ultrasound is used to pinpoint the exact location of the fluid and then inject it. This eliminates the risk of damage to the intestines or other organs .
Let’s ensure safety.
This test can be safely performed even in people with coagulopathy. Even if the platelet count is low (above 20,000), a blood transfusion is usually not required .
Rare causes: pancreatic ascites and nephrotic syndrome
Sometimes ascites is not necessarily caused by liver disease or cancer.
• Pancreatic ascites: When the pancreas becomes inflamed or damaged, fluid can leak into the abdomen. This fluid contains a chemical called amylase that is very high (>1000 U/L) .
• Nephrotic Syndrome: When protein is lost from the body due to kidney disease (Nephrotic Syndrome), the body may become edematous. This also falls under the category of low SAAG (<1.1) .
Treatment options: A causal approach
Once the disease is identified, treatment becomes easier.
Salt reduction and diuretic medications
If ascites is due to cirrhosis (high SAAG), the first step is to reduce salt intake (less than 2 grams per day) . The doctor will also prescribe diuretics such as Spironolactone and Furosemide. This usually starts with 100 mg of Spironolactone and 40 mg of Furosemide .
Refractory Ascites
Ascites that does not improve despite medication is called ‘refractory ascites’. Such patients may require periodic drainage of fluid from the abdomen (Therapeutic Paracentesis). When more than 5 liters of fluid is removed, an albumin drip may be given to prevent a drop in blood pressure . Sometimes a treatment called TIPS (Transjugular Intrahepatic Portosystemic Shunt) and ultimately a liver transplant may be required .
On the other hand, if the ascites is caused by cancer or TB (low SAAG), the above medications will not be effective. They should be given chemotherapy or TB medications .
Conclusion
Do not take swelling in the abdomen lightly. The real cause of this can be found through proper testing (Paracentesis & SAAG calculation). Studies have shown that SAAG is 97% more accurate than the old protein test. It helps doctors differentiate whether it is liver disease, heart disease, or cancer. Timely diagnosis and treatment can help increase the patient’s lifespan and improve their quality of life.