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Forum Name: Liver Diseases
Question: Understanding blood test results (ALT)
|Guy424 - Tue Jun 15, 2010 8:42 pm||
I recently had blood taken, and was told I had a problem with billirubin and ALT, which was 2.2 and 7. How do I interpret this? I am 25. I have not scheduled another appointment.
|Dr.M.Aroon kamath - Sun Jul 04, 2010 5:51 am||
The 'normal' laboratory reference ranges vary between laboratories. As you have not indicated the reference range, interpretation based on the values provided is not advisable.
However, i will discuss in brief, how these tests are interpreted.
Serum Bilirubin: this exists in the serum in two forms
- conjugated (water soluble)&
- the unconjugated (water insoluble) forms.
Normally, 90% or more of serum bilirubin is in the unconjugated form.
Normal values (one sample reference range):
- total bilirubin: 0.3-1.2 mg/dl (1.7-17.0 mmol/L),
- direct bilirubin: 0.1-0.4 mg/dl, &
- indirect bilirubin: 0.2-0.8 mg/dl.
An increase in serum bilirubin concentration to above 2.5 mg/dl results in clinical jaundice. When the total bilirubin level is raised and the major portion (90% or more) happens to be unconjugated, liver disease is unlikely. This situation raises two possibilities.
- Gilbert's syndrome: patients are usually young and otherwise healthy & asymptomatic individuals. It is an inherited disorder affecting conjugation of bilirubin in the liver. All the other standard liver function tests are normal. In these individuals, 90% or more of the total bilirubin will be unconjugated.
- Hemolysis is the other possibility.
The AST, ALT, and alkaline phosphatase (ALP) tests are most useful to make the distinction between hepatocellular and cholestatic disease.
Serum aminotransferases: are of two types.
- alanine aminotransferase (ALT) and
- aspartate aminotransferase (AST).
Elevations of these are the two of the most useful indicators of liver cell injury. The AST is less liver specific than the ALT.
Elevations of the AST level may also be seen in acute muscle injury, (cardiac or skeletal muscle). Mild degrees of ALT level elevation may occasionally be seen in skeletal muscle injury or even after vigorous physical exercise.Disproportionate elevations of the AST and ALT levels when compared with the alkaline phosphatase level arise in diseases that primarily affect hepatocytes (ex; viral hepatitis). The AST/ALT ratio is not very useful in determining the cause of liver injury, except in acute alcoholic hepatitis, wherein, the ratio is usually > 2 and the AST level is 400 IU/mL or lower.
Common causes of mild increases in AST and ALT levels is fatty liver disease seen most often in the context of obesity, diabetes, hyperlipidemia and alcohol abuse.
The ratio of AST to ALT may give additional clues as to the cause:
- In chronic liver disease with early cirrhosis ALT > AST,
- In chronic liver disease with established cirrhosis AST > ALT.
Extremes of the ratio of AST:ALT may also be sometimes useful:
- ratio >2 suggests alcoholic hepatitis, and
- <1.0 is suggests non-alcoholic liver disease.
Elevations of direct-reacting bilirubin does not always mean that a patient has a cholestatic (obstructive) liver disease.
In many types of liver disease raised or normal direct bilirubin levels may be seen, while the liver enzyme levels often elevated.
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