How is hepatic encephalopathy diagnosed?
Diagnosing hepatic encephalopathy is complex due to the variety of its neurological manifestations. Many other neurological and systemic diseases share the same symptoms, and it is essential to exclude them first. Your doctor will ask your several questions regarding your symptoms and how they started. They may also ask you symptoms to exclude other conditions and other questions to confirm liver disease including:
- The presence of jaundice
- If you are bruising easily
- If you had abdominal or leg swelling
- Bloody vomiting
Afterwards, they may ask for a battery of tests including neuropsychological tests, lab tests and perhaps some imaging results. Lab tests include:
- Liver function tests: Liver function tests include liver enzymes (ALT and AST), albumin level, and bilirubin levels. Liver enzymes are released when the liver is damaged, and bilirubin is a product of liver excretion. Albumin is a good measure of the liver’s ability to produce protein on the long-term, since it takes 21 days of liver damage for albumin levels to fall.
- Coagulation profile: One of the liver’s main functions is the production of coagulation factors, and estimating the level of prothrombin, the most important of those coagulation factors, is essential to diagnosing liver diseases. Prothrombin is the first indicator of the liver’s inability to produce protein because it can fall within a week of liver damage.
- Ammonia level in blood: The relationship between ammonia and hepatic encephalopathy is not as direct as mentioned before, and several other factors play a role. However, estimating the level of ammonia in blood can give a general picture at how advanced hepatic encephalopathy is.
- Kidney function tests: Although the kidneys are not directly linked to hepatic encephalopathy, patients with compromised kidney function have an accelerated course of hepatic encephalopathy as it decreases the rate of removal of ammonia and its product, urea, from the blood.
- EEG: Electroencephalography is a recording of the electrical activity of the brain. It can be used to detect changes related to the brain’s ability to conduct electric current. It can show some changes in hepatic encephalopathy, but it is not done routinely unless a different diagnosis is suspected.
In addition, there is a variety of imaging studies that can be of use in hepatic encephalopathy. However, none are specific for the disease, and they only serve to confirm a diagnosis or exclude other probable diagnoses. The most commonly used are:
- Liver ultrasound: Liver ultrasound is used to assess the liver. It can show liver cirrhosis and can be used to guide some shunting procedures as mentioned above.
- Brain MRI: Brain MRI is the most used to detect changes of hepatic encephalopathy. Magnetic resonance imaging can view soft tissue including the brain in high resolution and show some changes associated with symptoms and lab tests. It can also be used to exclude other neurological causes of symptoms such as Alzheimer and multiple sclerosis, but it remains a less specific tool.