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

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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