Liver function tests are a comprehensive test performed when liver dysfunction is suspected. What does it consist on ? What are the standards? Should we be fasting or not? How to interpret its results? What are the diseases it can reveal? Turn of the question.
The liver blood test makes it possible to identify certain pathologies of the liver. Several elements are then assayed: hepatic enzymes (alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase), bilirubin and albumin. The assay of this protein makes it possible to evaluate the synthetic capacities of the liver.
Liver function tests may be requested to confirm an abnormal liver function and determine its origin. For example in the event of jaundice, dark urine, in the presence of unexplained nausea, diarrhea or vomiting, clear or discolored stools, weight loss or even fatigue, a liver test is recommended. It also makes it possible to control the evolution of liver damage once the diagnosis has been made.
To perform a liver test, a blood test must be taken. From this, an assay of enzymes produced by the liver or specific to this organ is performed. Here are the main ones:
- gamma-glutamyl transpeptidase (Gamma-GT or GGT)
Dr Jacques Amselem, general practitioner in Seine-et-Marne, details the standards for the results of a liver test.
- ASAT (SGOT): <40 U / L
- TOOL (SGPT): <41 U / L
- Alkaline Phosphates: 40 to 129 U / L
- GGT: <60 U / L
- Total bilirubin: <21 µmol / L
- Prothrombin rate: 70 to 100%
Although these indicators alone cannot confirm a particular pathology, certain dosages are nevertheless symptomatic of specific attacks.
Abnormally high bilirubin levels may indicate cholestasis, pancreatitis or pancreatic cancer. Liver failure is usually indicated by an abnormally low prothrombin level.
An increase in transaminases (ALAT and ASAT) shows the presence of cytolysis, corresponding to the destruction of liver cells during viral hepatitis, alcoholism, drug intoxication or even a gallbladder problem. In any case, a precise interpretation of these at least complex examinations must be made and the results should be compared to other symptoms before drawing any conclusions. Other blood tests as well as additional examinations – MRI, ultrasound of the liver and bile ducts, etc. – should be performed.
Thanks to Dr Jacques Amselem, general practitioner in Seine-et-Marne for his medical validation.
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