Abnormal liver function tests

A simplified guide for young clinicians about the interpretation of liver function tests

1. Abnormal liver function tests Ahmed Adel Abdelhakeem Gi & liver unit, internal medicine dept., auh

2. topics Introduction Individual tests Management Initial evaluation Hepatocellular-predominant Cholestasis-predominant Suggested protocol

3. introduction abnormal liver function tests in up to 17.5% of the asymptomatic general population 58% of these patients they are not adequately followed up Abnormal liver function tests can sometimes be associated with extrahepatic diseases and physiological conditions A normal liver function test does not necessarily exclude liver disease Blood levels of ALT & AST usually reflect the integrity of hepatocytes, ALP & GGT indicate cholestasis and bilirubin, albumin, prothrombin indicate overall synthetic function However, none of these is specific for liver disease

4. introduction Altered liver function tests are increasingly encountered in clinical practice. This is mainly because measurement of aminotransferase and hepatic markers of cholestasis (ALP and GGT) is included in the screening of blood donors and hospitalization due to non-hepatic conditions Measurement of liver function tests as part of screening procedures, such as periodic “health check ups” or insurance physicals, can lead to problems where asymptomatic people are found to have a mildly altered liver biochemistry. You should therefore be cautious about ordering tests in apparently healthy patients, and discuss the possibility of false positive results with the patient as part of obtaining their consent to the test.

5. Isolated Abnormalities in Liver Test Results A common clinical scenario Of these tests only the GGT is liver specific An isolated elevation of just one of the other test values should raise suspicion that a source other than the liver is the cause

6. Aminotransferases AST and ALT are both intracellular enzymes, so their presence in the bloodstream can be an indicator of hepatocellular injury also expressed in the heart, skeletal muscle, and red blood cells Alanine aminotransferase (ALT) is considered more specific than aspartate aminotransferase (AST) for hepatocellular injury because it is predominantly represented in the liver, with low concentrations in other tissues. The ratio of AST/ALT is of little benefit in sorting out the cause of liver injury except in acute alcoholic hepatitis, in which the ratio is usually greater than 2 .

7. Aminotransferases AST/ALT Ratio Greater than 2:1 is highly suggestive of alcoholic hepatitis Greater than 4:1 in toxic hepatitis, ischemic hepatitis and Wilson’s disease More AST elevation but still < 2:1 in HCV-related cirrhosis

8. Alkaline phosphatase Both liver and bone diseases can cause a pathological elevation of serum alkaline phosphatase (ALP), although increased ALP may originate from the placenta, kidney, intestine, and leukocytes. You can find increased serum ALP in some physiological conditions, such as adolescence (bone origin) and pregnancy (placenta origin).

9. Alkaline phosphatase Causes of raised Alkaline phosphatase other than cholestasis: Pregnancy Renal diseases Intestinal injury Sepsis Bone diseases Heart failure Concomitant rising of GGT confirms liver origin.

10. GGT Both ALP and GGT are synthesized and released by cells lining the bile ducts, and they can be released into the bloodstream by cholestasis and the accumulation of bile salts. For this reason, ALP and GGT can act as markers of cholestasis The enzyme (GGT) is present in renal tubules, the liver, pancreas, and intestine. Although intracellular GGT levels are higher in organs other than the liver, GGT activity in the serum comes mainly from the liver GGT is contained in the micro- somes , and drugs such as anticonvulsants and oral contraceptives can induce its activity

11. GGT The GGTP level is too sensitive, frequently elevated when no liver disease is apparent. A GGTP test is useful in only two instances: It confers liver specificity to an elevated alkaline phosphatase level; In aminotransferase level elevations with AST/ALT ratio greater than 2, elevation of GGTP further supports alcoholic liver disease. To monitor abstinence from alcohol. An isolated elevation of the GGTP level does not need to be further evaluated unless there are additional clinical risk factors for liver disease

12. GGT Causes of raised GGT: Alcoholic liver diseases Drugs (COCs, anticonvulsants) Obesity Diabetes Pancreatic diseases Intestinal injury Renal diseases

13. Serum albumin Causes of hypoalbuminemia: Chronic liver diseases Nephrotic syndrome Inflammation (with increased CRP) Malabsorption Malnutrition (with decreased urea, creatinine, calcium, iron and lymphocytes)

14. Serum bilirubin Normally, 90% or more of measured serum bilirubin is unconjugated (indirect-reacting). When the total bilirubin level is elevated and fractionation shows that the major portion (≥90%) is unconjugated, liver disease is never the explanation. Instead, the clinician should suspect one of two explanations: Gilbert disease or hemolysis Gilbert syndrome .: is seen in about 5% of the general population and causes only mild hyperbilirubinemia without symptoms. It is not associated with liver disease. Interestingly, fasting and intercurrent illnesses such as influenza often make the level of unconjugated bilirubin even higher in those with Gilbert syndrome. This syndrome is easily diagnosed when all standard liver-test results are normal and 90% or more of the total bilirubin is unconjugated. There is no need for an imaging study or liver biopsy in cases of suspected Gilbert syndrome.

15. Serum bilirubin Indirect bilirubin Direct bilirubin Enzymes Anemia & hemolysis Gilbert > 90% of total bili Normal Normal No Hemolysis > 90% of total bili Normal Normal Yes Liver disease Normal or elevated Always elevated Elevated ---

16. initial evaluation Evaluation should be individualized Exclude extrahepatic conditions (pregnancy, ..) Age, sex, alcohol, drugs (?herbals) Type of abnormality: Predominantly hepatocellular or cholestatic ? Severity of abnormality: mild, moderate to severe Etiology of underlying condition Consider a step-wise approach

17. diagnosis by type of abnormality Abnormal liver function tests may show two (sometimes overlapping) patterns: Hepatocellular predominant - increases mainly in aminotransferases (AST and ALT) with or without a lesser increase in hepatic markers of cholestasis Cholestatic predominant - increases mainly in markers of cholestasis (ALP and GGT) with or without a lesser increase in aminotransferases.

18. Hepatocellular predominant type Raised transaminases (ALT, AST) No or mild elevation of bilirubin and ALP May be asymptomatic or symptomatic Synonym: hepatitis SEVERITY AND ETIOLOGY OF SEVERITY SHOULD BE DETERMINED

19. ETIOLOGY OF Hepatitis LFTs Differential diagnosis of hepatocellular type (hepatitis, transaminitis): Viral hepatitis Toxic hepatitis Alcoholic hepatitis Ischemic hepatitis NASH AIH Wilson’s Hemochromatosis Celiac disease Alpha 1 antitrypsin deficiency

20. Workup for a case of hepatitis/transaminitis Step I: clinical history and examination (extrahepatic condition, BMI, drugs or alcohol). USS should be done at this stage. Step II: order HCV Ab, HBsAg, ANA and iron studies. If positive treat according. Step III: if all are negative order Wilson screen, other autoAbs, celiac screen and alpha 1 antitrypsin. Step IV: If all are negative consider liver biopsy, think about NASH.

21. diagnosis by severity The degree of abnormality of aminotransferases may be useful for narrowing the differential diagnosis Although there is no universal definition of mild, moderate, and severe abnormality of aminotransferases, the degree of abnormality can practically considered to be: Mild when the enzyme level is less than five times the upper reference value Severe when AST and ALT are greater than 10 times the upper reference value.

22. diagnosis by severity Common causes of mild transaminitis (up to 5 times): Chronic viral hepatitis Alcoholic hepatitis NASH AIH Hemochromatosis

23. diagnosis by severity Common causes of moderate to severe transaminitis (more than 5 times): Acute viral hepatitis Ischemic hepatitis Toxins and drug-induced AIH

24. diagnosis by etiology Chronic Viral Hepatitis (C) Endemic areas Mild transaminitis in most cases Usually accidentally discovered History of blood transfusion and/or risk exposure Detection of hepatitis C virus RNA in serum by polymerase chain reaction technique is used to confirm active viral infection and replication. A negative polymerase chain reaction in patients positive for anti-hepatitis C virus antibodies needs to be repeated in three months to avoid false negatives If aminotransferases abnormality persists despite negative viremia, you must rule out other causes of liver injury

25. diagnosis by etiology Chronic Viral Hepatitis (B) Endemic areas More prominent transaminitis than HCV, although in most cases it is mild Usually accidentally discovered History of blood transfusion and/or risk exposure The presence of hepatitis B virus surface antigen (HBsAg), hepatitis B virus e antigen (HBeAg) and antibody (anti-HBeAb), and hepatitis B virus core antibodies (IgG and IgM anti- HBc ) are the principal markers that help define the status of people infected with hepatitis B virus

26. diagnosis by etiology Chronic Viral Hepatitis (B) You may want to obtain hepatitis B virus DNA to identify patients with active replication and to monitor antiviral therapy Due to the availability of hepatitis B virus vaccine, you should screen family members and intimate contacts of patients with hepatitis B virus infection by testing for HBsAg and HBcAb. If negative, you should recommend immunoprophylaxis.

27. diagnosis by etiology Autoimmune hepatitis You should suspect a diagnosis of autoimmune hepatitis in young and middle aged females with concomitant autoimmune disorders (for example, rheumatological diseases and autoimmune thyroiditis). The prevalence of the disease is about 1:6000 to 1:7000. Up to 80% of patients with autoimmune hepatitis may have polyclonal hypergammaglobulinaemia in the absence of liver cirrhosis. The criteria for diagnosing autoimmune hepatitis are complex and include liver biopsy

28. diagnosis by etiology Autoimmune hepatitis Testing for antinuclear antibodies, antibodies to smooth muscle, anti-liver/kidney microsomal antibodies, and antibodies to the soluble liver antigen has an important diagnostic role and is used to categorize autoimmune hepatitis into three types: Type 1 - characterized by the presence of ANA and/or smooth muscle antibodies. This is the most common form of autoimmune hepatitis and usually affects young women Type 2 - characterized by the presence of anti-liver/kidney microsomal antibodies and is a disease with a prevalent onset in childhood Type 3 - clinically indistinguishable from type 1 except for the presence of antibodies to the soluble liver antigen.

29. diagnosis by etiology Hereditary haemochromatosis This is an autosomal recessive condition. Between 1:200 and 1:300 people are homozygous for common mutations. The disease is characterized by a pathological deposition of iron in the liver, pancreas, and heart. Although a positive family history and the presence of congestive heart failure and diabetes mellitus may aid the diagnosis, you should also measure serum ferritin, iron, and the transferrin saturation index (serum iron/total iron binding capacity) in patients with altered aminotransferases Symptoms of haemochromatosis may arise late during the course of the disease. High serum ferritin levels and, more importantly, a transferrin saturation index larger than 45% strongly suggest haemochromatosis.

30. diagnosis by etiology Hereditary haemochromatosis Patients who are homozygous for the C282Y mutation have the greatest risk of iron overload Mutation analysis for the haemochromatosis (HFE) gene may confirm the diagnosis, although a negative test does not exclude the presence of non-HFE-related haemochromatosis. In these patients, you should suggest a liver biopsy for both diagnostic and prognostic purposes. Finally, you should offer screening to first degree relatives of affected patients by genetic testing, even if they are asymptomatic and have normal liver enzymes. Normal liver biochemistry can be present in young people

31. diagnosis by etiology When to think about it? Any adult with liver disease, especially men and post-menopausal women Patients with symptoms suggestive of or having a family history of HH Initial evaluation The initial evaluation for iron overload includes measurement of serum ferritin, iron, iron-binding capacity, and transferrin saturation levels. Transferrin saturation less than 45%, in addition to normal serum ferritin level usually rules out iron overload (negative predictive value of 97%), and no further testing is necessary Transferrin saturation greater than 45% and/or a serum ferritin above normal level warrants further investigation. However, these thresholds are low, and most patients who exceed these limits will not prove to have iron overload Confirmation HFE gene mutation: homozygosity  C282Y  genes, occasionally a compound heterozygote ( C282Y-H63D ). Homozygosity for  H63D  does not usually result in excess iron absorption

32. diagnosis by etiology Limitations of serum-based iron studies Both iron and ferritin are stored in liver cells, any condition that results in hepatocyte injury and release of intracellular contents into the blood will falsely raise iron, transferrin saturation, and ferritin levels. Therefore, in acute hepatic injury these tests will falsely suggest iron overload. Acute inflammation outside the liver may also falsely elevate the results of serum-based iron tests  In a young patient with this condition who has not yet had enough time to accumulate iron (especially the premenopausal woman), screening tests for iron overload may be normal Homozygosity for C282Y and compound heterozygosity for C282Y/H63D are diagnostic of HH and a liver biopsy with hepatic iron index (HII) estimation, which was previously the criteria for diagnosis, is no longer needed to confirm the diagnosis of HH in these patients

33. diagnosis by etiology NAFLD Fatty infiltration of the liver, with or without associated inflammation and fibrosis, is thought to be the most common cause of mild abnormality of aminotransferases in the general population in Western countries. Nevertheless, the exact prevalence of non-alcoholic fatty liver disease is quite difficult to ascertain because the disease is asymptomatic and there are no blood tests to confirm the diagnosis Although risk factors for non-alcoholic fatty liver disease such as obesity, diabetes mellitus, and hyperlipidemia are present in a variable proportion of affected patients, they are not specific. Therefore, the initial evaluation of a patient with abnormal liver function tests and suspected non-alcoholic fatty liver disease should include a complete serological evaluation to exclude other causes of liver disease

34. diagnosis by etiology Alcoholic liver disease Low ALT activity. This is explained by the fact that both AST and ALT need vitamin B-6 for their enzymatic reaction, although the effect of vitamin B-6 deficiency is greater on ALT activity than on AST activity, and people with alcoholic liver disease usually have vitamin B-6 deficiency Abnormal GGT and normal ALP levels Macrocytosis Chronic pancreatitis In acute alcoholic hepatitis the AST is typically in the 100 to 200 IU/L range, even in severe disease, and the ALT level may be normal, even in severe cases. The AST level is higher than the ALT level, and the ratio is greater than 2:1 in 70% of patients. A ratio greater than 3 is strongly indicative of alcoholic hepatitis. An important corollary is that an AST greater than 500 IU/L or an ALT greater than 200 IU/L is not likely to be explained by acute alcoholic hepatitis—even in an alcoholic patient—and should suggest another etiology

35. diagnosis by etiology Alcoholic liver disease The degrees of bilirubin level increase and prothrombin time elevation are better indicators of severity of disease. In alcoholic hepatitis, the Maddrey discriminant function (MDF), a disease-specific prognostic score which indicates the severity of liver injury, has been developed. The formula to calculate the score is as follows: MDF = 4.6 (patient's prothrombin time − control prothrombin time) + total bilirubin (mg/ dL ) Patients who have a score of 32 or greater have an increased risk of death, with a 1-month mortality rate of 30% to 50%.

36. diagnosis by etiology Acute Viral Hepatitis One of the most common underlying conditions in patients presenting with severely abnormal aminotransferases These patients may also have non-specific symptoms (such as malaise, low grade fever, or arthralgia) or symptoms and signs suggesting liver disease (including jaundice and right upper quadrant pain) All of the major (A, B, C, D, and E) and minor (cytomegalovirus, Epstein-Barr virus, herpes virus, and adenovirus) hepatitis viruses can be responsible for increased aminotransferases, which may exceed 10 to 15 times the upper reference value. Condition Diagnosis Acute HAV HAV IgM Acute HBV HBsAg + HBcIgM Acute HCV HCV RNA Acute EBV, CMV Specific IgM or PCR

37. diagnosis by etiology Ischemic and toxic hepatitis Ischemic and toxic hepatitis may cause a severe increase in aminotransferases (up to 70 times the upper reference limit). Because zone 3 of the hepatic acinus is more prone to ischemic and toxic damage and is richer in AST, this aminotransferase tends to peak before ALT when hypoxia and toxins are the cause of the hepatic damage. About 60% of cases of severely elevated hepatic AST may be attributable to ischemic or toxic liver injury You should suspect ischemic or hypoxic damage when precipitating events are present. These can be: hypotension, myocardial infarction, hemorrhage or other low flow hemodynamic conditions.

38. diagnosis by etiology Ischemic and toxic hepatitis In these patients, the presence of high serum concentrations of lactate dehydrogenase as a marker of ischemic damage may further support the diagnosis There are no specific serological tests for identifying this condition Taking a careful history is important for diagnosing drug induced hepatotoxicity. You should obtain a detailed pharmacological history from the patient that includes over the counter medications and herbal remedies

39. diagnosis by etiology Other less common causes of severe transaminitis Both acute alcoholic hepatitis and autoimmune hepatitis may present with a clinical picture characterized by a severe abnormality in aminotransferases and jaundice. Acute extrahepatic biliary tract obstruction may be responsible for a peak in aminotransferases that rapidly declines once the obstruction has been removed. In this clinical situation, both the presence of symptoms (biliary pain and nausea) and ultrasound evidence of biliary duct dilation usually provide a diagnosis. Finally, Wilson’s disease may also present with severely elevated aminotransferases due to the massive release of copper, and is responsible for fulminant hepatitis

40. CHOLESTATIC predominant type Raised BILIRUBIN, ALP AND GGT No or mild elevation of ALT AND AST SYMPTOMS OF CHOLESTASIS TYPE AND ETIOLOGY SHOULD BE DETERMINED

41. ETIOLOGY OF CHOLESTASIS Intrahepatic causes: PBC PSC Drugs Viral Hepatitis AIH Granulomas Extrahepatic causes: Choledocholithiasis Malignancy Parasites Autoimmune pancreatitis

42. evaluation of cholestasis A history of itching in a middle aged woman with concomitant autoimmune diseases (autoimmune thyroiditis and rheumatoid arthritis) should prompt testing for antimitochondrial antibodies (positive in 95% of patients with primary biliary cirrhosis). A history of inflammatory bowel disease (most commonly ulcerative colitis, associated in about 70% of patients) should alert you to a diagnosis of primary sclerosing cholangitis ALP and GGT may have a mildly fluctuating pattern with normal serum bilirubin levels in choledocholithiasis. This situation may be preceded by a peak in aminotransferases and typical symptoms, such as: Right upper quadrant pain, nausea and vomiting and Jaundice. This clinical picture may also precede jaundice in patients with carcinoma of the pancreas. In these patients, liver ultrasound examination may initially show dilated bile ducts. Further imaging techniques (computed tomography and magnetic resonance cholangiopancreatography) are therefore often needed to confirm the diagnosis

43. evaluation of cholestasis Many commonly used drugs, such as antihypertensives (for example, angiotensin converting enzyme inhibitors) or hormones (for example, estrogens), may cause cholestasis and can be overlooked. In patients with drug induced cholestasis, liver ultrasound examination is often unremarkable Unconjugated bilirubin may be increased because of augmented bilirubin production or decreased hepatic uptake and/or conjugation. The most common condition associated with isolated elevated bilirubin (unconjugated) in adults is Gilbert’s syndrome, which is caused by a genetic defect that affects about 5% of the population

44. WORKUP OF A CASE OF CHOLESTASIS Isolated cholestasis Extrahepatic cause (stone or tumor) PBC PSC Drug-induced (estrogen, AZA) IHCP Cholestatic hepatitis Viral hepatitis Drug-induced (NSAID, Amoxiclav, macrolides, AZA) AIH Ischemic hepatitis AFLP Cholangitis

45. WORKUP OF A CASE OF CHOLESTASIS ISOLATED CHOLESTASIS: Consider clinical history taking and examination (age and sex, drugs, toxins, pregnancy, any pain, hx of stones, weight loss) Order USS and/or MSCT abdomen if USS shows dilated biliary channels If imaging is negative > Order AMA > If positive: treat as PBC If AMA is negative > order MRCP or ERCP > PSC If MRCP or ERCP are negative > consider liver biopsy > (AMA -ve PBC, small duct PSC, AIH, Granulomas)

46. WORKUP OF A CASE OF CHOLESTASIS CHOLESTATIC HEPATITIS: (same as hepatitis workup) Step I: clinical history and examination (extrahepatic condition, drugs or alcohol). USS should be done at this stage. Step II: order HCV Ab, HBsAg, ANA and iron studies. If positive treat according. Step III: if all are negative order Wilson screen, other autoAbs, celiac screen and alpha 1 antitrypsin. Step IV: If all are negative consider liver biopsy. NASH rarely presents with high bilirubin.

47. suggested protocol FOR HEPATITIS

48. suggested protocol FOR CHOLESTASIS Clinical + USS (stop drugs, ? pregnancy) If IHBCD IMAGING If no IHBCD AMA if positive: PBC If negative: MRCP or ERCP if positive: PSC If negative: LIVER BIOPSY

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