1. Abnormal liver enzyme levels liver enzyme levels symptoms or signs suggestive of liver disease isolated, unexpected finding challenge even for the experienced clinician and set off a battery of further tests and consultations

2. Liver disease Liver disease is reflected by biochemical abnormalities of 1 of 2 different hepatic systems or of liver function

3. Where, when and how: a schematic approach to liver enzyme alteration 10 times the upper reference limit, or mild, moderate or marked

4. Hepatocellular predominance the most sensitive and specific aminotransferase threshold level to identify acute injury (viral hepatitis) lies within the moderate range of increase (5–10 times the URL), –at 200 IU/L for AST [sensitivity 91%, specificity 95%] –300 IU/L for ALT [sensitivity 96%, specificity 94%])

5. Hepatocellular predominance

6. Very high aminotransferase levels (> 75 times the upper reference limit) indicate ischemic or toxic liver injury in more than 90% of cases of acute hepatic injury, whereas they are less commonly observed with acute viral hepatitis

7. Hepatocellular predominance

10. Mild ↓ ↓ ↑

11. ALT/ALP ratio < 2 Abnormal ALP levels may also be a sign of metastatic cancer of the liver, lymphoma or infiltrative diseases such as sarcoidosis

12. Reference for liver tests

13. Case #1 ALT/AP = 0.2

14. Case #1

16. Case #2 ALT/AP = 0.06

17. Case #2

18. Case #3 NORMAL AST/ALT = 1.6 HEPATOCELLULAR MILD (<5xURL)

19. Mild ↓ ↓ ↑

20. Case #3

21. Case #4 ALT/AP = 5.3 HEPATOCELLULAR MODERATE/MARKED (5-10 - >10 xURL) AST/ALT = 0.5

22. Case #4