Doctors Newsletter Winter Page 2 Editorial Dr Colin Goldschmidt Pages 3-4 Interpretation of Liver Function Tests Dr Grahame Caldwell Pages 5-6 Viral Hepatitis Dr Ian Chambers Page 7 Haematological Changes in Liver Disease Dr Debbie Clark Page 8 Latest News New Mesothelin Test Answers to Quiz
Editorial Making Sense of Pathology Information Dr Colin Goldschmidt Chief Executive Officer It is my pleasure to introduce this latest edition of the Doctors Newsletter. Our theme for this issue is the liver, as tests of liver function are one of our most frequently requested profiles, and primary liver disease is of increasing prominence in Australia. The articles offered in this Newsletter cover biochemical, microbiological, and haematological aspects of liver disease and we hope that you will find them useful in your daily clinical work. Various estimates suggest that medical knowledge doubles every five years or less. Such a rapid pace constantly challenges all of us, and underpins a need to try to make sense of the sea of information we face on a daily basis. How can we help, as far as pathology is concerned? In our Practice, we believe it is worthwhile putting considerable thought and effort into providing interpretive guidance on results we generate. Interpretive comments mean effective communication, not just more facts or numbers. For this reason we try, wherever possible, to add such comments in the form of accompanying text or interpretive algorithm. These comments, although often pre-prepared, are added to individual results by a pathologist or senior scientist in response to the available information. Where a patient s profile is difficult to interpret, or may suggest that urgent action is required, we may phone you directly to discuss the results. We are fortunate to have a large team of pathologists at Douglass Hanly Moir and Barratt & Smith Pathology, and their expertise covers the entire spectrum of pathology testing. With the increasing complexity of currently available pathology tests, the need for sub-specialised pathologists is essential and here too, we are fortunate to have this in-depth expertise amongst our pathologist group. As part of our commitment to continuous improvement, we ensure that our advice takes account of the most up-to-date information on any given test. I am frequently asked why I believe that Douglass Hanly Moir and Barratt & Smith Pathology is different from other pathology groups. Even though I might not be entirely neutral in my view on this subject, I do have a list of value-added features which I believe differentiate us from our competitors. However, I always come back to our outstanding pathologist group as the major differentiating feature. Whether by virtue of interpretive comment or telephone consultation, our super-specialised pathologists provide current, educated and practical advice which we hope allows you to make better sense of the results issued. They are the dynamic link between your practice and the increasingly complex world of pathology testing and, judging by the number of calls our pathologists receive each day from referring doctors, their input appears to be much appreciated. So, please feel free to make use of this differentiated service and phone a Douglass Hanly Moir or Barratt & Smith pathologist today! Finally, it remains for me to extend to you my warmest wishes and to thank you most sincerely for your ongoing support. With my warmest regards, Dr Colin Goldschmidt M.B.B.Ch., F.R.C.P.A., F.A.I.C.D. Chief Executive Officer Douglass Hanly Moir Pathology Barratt & Smith Pathology 2
Interpretation of Liver Function Tests and secreted into the bile and thence the gut. Conjugated bilirubin is water soluble and appears in the urine. In excess, it is responsible for the dark discolouration of the urine in obstructive jaundice. In the normal physiological state, serum bilirubin is predominantly unconjugated. If there is haemolysis, ineffective erythropoiesis, or resorption of a haematoma, unconjugated ( indirect ) bilirubin will rise. Conjugated ( direct ) hyperbilirubinaemia occurs in parenchymal liver disease and as a result of intrahepatic or extrahepatic obstruction to bile flow. Doctors frequently face the need to interpret abnormalities in Liver Function Tests (LFT), as these are among the most frequently requested pathology investigations. The problem is compounded by the fact that the apparent severity of the abnormalities does not necessarily reflect the extent of the underlying liver disease. Some patients, for example, with advanced parenchymal cell loss have only mildly abnormal LFT results. On the other hand, abnormalities in the LFT group such as elevation in enzyme levels may result from disease remote from the liver. This is particularly a problem where a liver enzyme also is present in other tissues of the body. This article will briefly discuss the seven tests shown below that are normally performed in response to a request for LFT. Three recent examples from our laboratory of abnormal LFT results illustrating the various patterns of disease also are included. Protein is used in conjunction with albumin to estimate globulin levels and falls within the LFT group. This, however, will not be discussed, as the significance of globulin values has already been considered in a previous newsletter article. Liver Function Tests (excluding Total Protein & Globulins) Bilirubin Alkaline Phosphatase (ALP) Gamma-Glutamyltransferase (GGT) Lactate Dehydrogenase (LD) Aspartate Transaminase (AST) Alanine Transaminase (ALT) Albumin Bilirubin Dr Grahame Caldwell Director - Biochemistry Bilirubin is formed from the physiological lysis of red blood cells. As unconjugated bilirubin, it is transported to the liver loosely bound to albumin. Unconjugated bilirubin is insoluble in water and therefore does not appear in the urine. Within the liver it is conjugated to bilirubin glucuronide Bilirubin levels rise in a wide variety of liver disorders. Below is a list of common causes of an isolated rise in bilirubin levels. Some causes of an isolated elevated bilirubin: Haemolysis Ineffective erythropoiesis (eg megaloblastic anaemia) Resorption of haematoma Drugs (eg rifampicin) Genetic metabolic defects (eg Gilbert s syndrome) Alkaline Phosphatase Alkaline phosphatase originates from two main sources: liver and bone. It is also present in other tissues including placenta, leukocytes, intestine, and kidney. A first step in determining the cause of a raised ALP is to identify the source of the enzyme. This may be apparent from the clinical assessment and investigations including the remaining LFT results. However, if necessary, isoenzyme studies may be used to determine the tissue source. Raised hepatic ALP is characteristically associated with cholestasis. Common causes of raised ALP: Pregnancy Normal bone growth (children and adolescents) Bile duct obstruction (eg stones, malignancy) Drug-induced cholestasis Metastatic liver disease Primary biliary cirrhosis Sclerosing cholangitis Bone disease Gamma-Glutamyltransferase Gamma-glutamyltransferase (GGT) is present in all cells except skeletal muscle. In most cases, however, abnormal levels of this enzyme tend to be specific for the liver. The primary source of GGT is from biliary epithelial cells and periportal hepatocytes. GGT is useful as a sensitive marker for hepatobiliary status; raised serum levels are caused by enzyme induction and cholestasis. Common causes of a raised GGT: Alcohol Drugs (eg anticonvulsants) Biliary obstruction Hepatitis Non-alcoholic fatty liver 3
Interpretation of Liver Function Tests Aspartate Aminotransaminase (AST) and Alanine Aminotransaminase (ALT) These are released as a result of hepatocellular injury for which they are excellent markers. AST is present in other tissues, eg skeletal muscle, whereas ALT tends to be more specific for the liver. ALT is also confined to the cell cytosol in contrast to AST which is not only present in the cytosol but also in cell mitochondria. In most instances, the measured AST level does not significantly exceed the ALT value. In cases of severe liver injury or hepatic necrosis, however, AST may be substantially raised and exceed the level of ALT. Common causes of a raised ALT and AST: Viral hepatitis Drugs prescription, over-the-counter and alternative health preparations Exposure to chemicals and toxins Ischaemic liver injury Autoimmune disorders (including coeliac disease) Haemochromatosis and other genetic disorders Non-alcoholic fatty liver Very high aminotransferase levels characteristically may be associated with acute viral hepatitis, ischaemia or toxic injury due to chemicals or drugs, eg paracetamol overdose. Lactate Dehydrogenase Lactate dehydrogenase (LD) measurement is included in the LFT group but is widely distributed in body tissues and exists in the form of five isoenzymes. Common causes of a raised LD: Artefact Muscle disease Cardiac disease (eg infarction) Malignancy (primary and metastatic) Haematological disorders (eg haemolysis, megaloblastic anaemia, leukaemias) Pulmonary disease Infection (eg infectious mononucleosis) A haemolysed specimen due to a difficult collection or delayed separation may result in an artefactual rise in the LD level; LD is therefore a surrogate marker of specimen integrity. Very high levels of LD may be encountered in intravascular haemolysis, eg due to prosthetic valve, and in disseminated malignant disease. If the cause of a raised LD is unclear, isoenzyme evaluation may be considered. Albumin The liver synthesises and excretes approximately 10g of albumin daily. The half-life of albumin is about 18-20 days and with progressive liver disease, the serum albumin level falls. A low serum albumin is therefore a useful marker of chronic liver disease, and the level tends to correlate with prognosis. A number of other factors such as nutritional status, urinary and gastrointestinal loss also may significantly influence serum albumin levels. Example 1 - Male aged 26 Bilirubin 205 umol/l (0 20) ALP 213 U/L (30 115) GGT 159 U/L (0 45) LD 1387 U/L (100 225) AST 2887 U/L (0 40) ALT 3094 U/L (0 40) Albumin 39 g/l (38 55) This patient has acute viral hepatitis. He was clinically jaundiced and this is confirmed by the raised bilirubin. The urine was dark, consistent with an obstructive element. Very high transaminases are characteristic of acute viral hepatitis. The normal serum albumin is consistent with the lack of any underlying chronic liver disease. Serology was positive for Hepatitis A. Example 2 - Male aged 55 Bilirubin 81 umol/l (0 20) ALP 217 U/L (30 115) GGT 83 U/L (0 45) LD 411 U/L (100 225) AST 119 U/L (0 40) ALT 50 U/L (0 40) Albumin 18 g/l (38 55) This patient has hepatic cirrhosis associated with a long history of alcohol abuse. The LFT results show an emerging cholestatic picture with elevated bilirubin together with AST and ALT values that are consistent with parenchymal cell loss and a significantly decreased albumin level that reflects compromised hepatic function. Example 3 - Male aged 78 Bilirubin 21 umol/l (0 20) ALP 494 U/L (30 115) GGT 737 U/L (0 45) LD 1196 U/L (100 225) AST 49 U/L (0 40) ALT 48 U/L (0 40) Albumin 42 g/l (38 55) The bilirubin, AST and ALT are minimally elevated. The ALP and GGT are both significantly raised; this combination is consistent with biliary obstruction which is most likely to be intrahepatic as the bilirubin is only minimally raised. The LD is also significantly raised. This pattern suggests the possibility of intrahepatic obstruction from metastases. Further investigation, including imaging of the liver, revealed metastases from a previous carcinoma of the colon. For any enquiries, please contact Dr Grahame Caldwell on (02) 98 555 380 4
Viral Hepatitis Hepatitis is most commonly characterised by elevations of ALT and AST to a degree disproportionately greater than any elevations in GGT and ALP which may also be present. While viral infection is a common cause of hepatitis, other causes must be considered in the appropriate context. These include alcohol and other drugs, autoimmune pathology and non-viral infectious causes such as leptospirosis and Q fever. The main viral agents causing hepatitis include the specifically hepatotropic agents Hepatitis A to E, but also EBV, CMV and sundry other viruses which are circulating in the community. While the latter group may commonly cause biochemical hepatitis, this tends to be an incidental finding and is rarely clinically significant. The morbidity and mortality associated with infection with Hepatitis A to E, however, is of huge clinical and economic importance worldwide. Hepatitis A Virus (HAV) Dr Ian Chambers Director - Microbiology HAV infection is spread person-to-person by the orofaecal route, or by ingestion of contaminated food or water. It is highly contagious and spreads rapidly between individuals in prolonged close contact. The declining incidence of infection in developed countries, but continuing endemicity in developing parts of the world, makes HAV, and vaccination against it, important issues for travellers overseas. HAV produces an acute hepatitis with a mean incubation of around 30 days. In children under 6 years infection is usually sub-clinical. There is no chronic carrier state and immunity after infection is life-long. Hepatitis B Virus (HBV) HBV is a global health problem, with an estimated 350 million HBV carriers worldwide. More than 500,000 deaths each year are attributable to the chronic sequelae of HBV such as cirrhosis and hepatocellular carcinoma. It is transmitted by cutaneous and mucosal exposure to infectious blood or body fluids, making sexual contact and needle-sharing the main identifiable routes of transmission in countries such as Australia. HBsAg is the hallmark of HBV infection. It appears 2-7 weeks before the onset of symptoms and most patients who recover from HBV infection clear HBsAg within 6 months. Persistence beyond this time implies chronic infection, which occurs in approximately 10% of infected adults. HBeAg is a marker of active viral replication, and its persistence in a chronic carrier of HBV indicates high infectivity and a greater likelihood of progression to chronic liver disease. However, the HBV pre-core mutant, being unable to synthesize HBeAg, is associated with ongoing viral replication and liver damage without detectable HBeAg. Hepatitis C Virus (HCV) HCV is spread by parenteral routes, most commonly (in Australia) by the sharing of contaminated needles. However, in more than 40% of cases no recent or readily identifiable risk factor can be identified. Liver disease caused by HCV is now the leading reason for liver transplantation in Australia. There is a high rate of subclinical infection with HCV. Only about 15-25% of cases of acute infection result in the development of jaundice. Those that do are less likely to progress to chronic disease which is seen in 50-70% of those infected. The presence of antibody to HCV does not distinguish between past or current infection. Nucleic acid detection by PCR is used to assess disease activity and for pre- and post-treatment evaluation. Hepatitis D Virus (HDV) HDV is a defective virus, which can only infect those who are co-infected with HBV. Its geographic distribution includes the Amazon basin, central Africa, the Mediterranean basin and the Middle East. HDV may cause a benign, acute hepatitis or lead to fulminant liver failure. In the chronic setting, patients may be asymptomatic carriers or may progress more rapidly to cirrhosis and hepatocellular carcinoma. While uncommon in Australia, it should be suspected in patients with chronic HBV who develop an acute hepatitis or have rapid progression of their liver disease. 5
Viral Hepatitis Hepatitis E Virus (HEV) HEV is an enterically-transmitted virus which is endemic to the Indian subcontinent and southeast and central Asia. While several epidemics have been reported from China and India, the Australian experience is of sporadic cases, mainly in returning travellers. Indigenous cases, however, have been reported from the Northern Territory. HEV does not cause chronic liver disease, but infection in pregnant women is associated with fulminant liver failure in approximately 25% of cases. Hepatitis Viruses Beyond A to E Approximately 15% of hepatitis infections remain unexplained, and causes continue to be sought. Hepatitis F virus (HFV) was initially identified as a possible hepatitis virus but there is insufficient evidence to corroborate this and the identity of HFV is in doubt. Hepatitis G Virus (HGV, also called GB virus) was initially cloned from the plasma of a surgeon with acute hepatitis and is closely related to HCV. It is found among blood donors and can be transmitted by transfusion but does not appear to be associated with hepatitis nor does it worsen the course of concurrent HCV infection. Tests for HGV are not currently available. Non-Hepatotropic Viruses and the Liver Many acute viral infections may cause transaminase elevation, but only a minority manifest as a clinically apparent hepatitis. The most frequently encountered of this group are Epstein-Barr virus and Cytomegalovirus, but others include Parvovirus B19, Herpes simplex, Dengue, Enterovirus and HIV. Requesting Hepatitis Testing Ordering the appropriate hepatitis tests is confusing because there are so many different serological markers, especially for Hepatitis B. In addition, Medicare restrictions add another layer of complexity when deciding which tests can be performed. The table provided is a guide to the tests which are relevant in the most common clinical settings and their interpretation. Confusion can be minimized by either specifying the individual markers by name or, if making a general request for Hepatitis serology, specifying the clinical context of the request e.g.? immunity Hep A and B or? acute hepatitis. Serological Markers For Hepatitis A, B, C Interpretation of Hepatitis Serology HBcAb HAV IgM HAV IgG HBsAg anti-hbs IgM Total HBeAg anti-hbe HBV PCR anti-hcv HCV PCR Interpretation + Acute Hepatitis A + or + Past Hepatitis A + + + + + Acute Hepatitis B + + + Hepatitis B carrier ( low-infectivity ) + + or + + + Hepatitis B carrier ( high-infectivity ) + + + Hepatitis B carrier (pre-core mutant) + + + Past, resolved Hepatitis B + Successful Hepatitis B vaccination + or + Acute Hepatitis C + + Chronic Hepatitis C + Resolved Hepatitis C KEY: Ab = antibody Ag = antigen HBV PCR - no medicare item yet For any enquiries, please contact Dr Ian Chambers on (02) 98 555 330 6
Haematological Changes in Liver Disease The Full Blood Count In chronic liver disease a number of changes occur in the full blood count and film; sometimes these findings may be the first indication of liver dysfunction. Haemoglobin Level Dr Debbie Clark Haematologist As in any chronic disease, the haemoglobin level may fall, especially in patients with advanced liver disease. Macrocytosis is a common finding. Target cells are sometimes present (see Figure 1), although when present in large numbers, suggest obstructive jaundice or haemoglobinopathy. Blood loss, for example from bleeding varices, may contribute to the anaemia. Dietary folate deficiency is common in patients with underlying alcohol abuse and alcohol itself may suppress haemopoiesis or cause sideroblastic change in the marrow. Occasionally, haemolysis may occur in patients with liver disorders. Interestingly, viral hepatitis may rarely be followed by aplastic anaemia. Coagulation Abnormalities A bleeding tendency is common in patients with chronic and severe liver disease and multiple haemostatic abnormalities may be present. This may cause difficulties where liver biopsy is required or may contribute to bleeding from varices. Liver parenchymal cells are responsible for production of most coagulation factors. In addition, biliary obstruction resulting in impaired absorption of Vitamin K can lead to further decreased synthesis of factors II, VII, IX and X. Coagulation tests such as the PT (prothrombin time) and APTT (activated partial thromboplastin time) are frequently prolonged in these circumstances. The prothrombin time is a particularly useful indicator of impaired liver function (in advanced cases); unlike the traditional biochemical liver function tests which are occasionally normal in advanced disease, it is a true test of the functional ability of the liver. Note that the INR, a test based on the prothrombin time, was designed for testing of warfarin-induced coagulopathy, rather than that of liver disease. Factor V and fibrinogen may also be reduced, and a functional impairment of fibrinogen (dysfibrinogenaemia) is found in many patients. Impaired removal of activated clotting factors and increased fibrinolytic activity may also be present. Figure 1 White Cells and Platelets In longstanding liver disease mild to moderate leucopenia, including neutropenia, is often seen. Less commonly, acute liver damage or infiltration may be associated with a neutrophil leukocytosis. The platelet count is commonly reduced in patients with cirrhosis; although hypersplenism, immune mediated destruction, and erythropoietin deficiency may be responsible for these changes, the exact mechanism remains uncertain. Perpherial blood film showing macrocytosis and target cells For any enquiries, please contact Dr Debbie Clark on (02) 98 555 472 7
Latest News - New Mesothelin Test Pleural mesothelioma Mesothelin Test Our practice is now able to offer Mesothelin (MESOMARK) testing for malignant mesothelioma. At present, we do not believe this assay has clinical utility for the general screening of patients at risk of malignant mesothelioma, but it will be useful for monitoring patients with a histological diagnosis of mesothelioma. You also may consider this test in patients at high risk of malignant mesothelioma, when diagnostic procedures have failed to confirm the diagnosis. Because of the difficulties in interpreting and managing patients with low or intermediate levels of Mesothelin, we believe that the test is better restricted to a relevant clinical specialist setting. Since the test has become available only recently, we are keen to monitor its performance and for this reason, we would appreciate all relevant clinical data including information regarding patient follow-up. The Mesothelin assay, at present, is performed weekly in our laboratory and the fee is $95 (excluding GST) per test. There is no Medicare rebate currently available for this assay. If you have any enquiries regarding this test, please do not hesitate to contact either Dr Grahame Caldwell or Dr Karl Baumgart on (02) 98 555 312. Mesothelioma in a pleural aspirate Answers to Quiz - Doctors Newsletter Autumn 2005 In our last issue, we showed three cases from our records and asked for the most likely diagnosis. Here are the answers: Question 1: This was a 13 year old girl presenting with lethargy, abdominal discomfort, jaundice and splenomegaly. The bilirubin and LD were elevated and the blood film showed spherocytes and increased polychromasia, findings consistent with spherocytic haemolysis. Diagnosis: hereditary spherocytosis. Question 2: This was a 28 year old man returning from an extended holiday in India, with fever, nausea, jaundice and hepatomegaly. Both AST and ALT were greater than 10,000U/L and the blood film showed atypical lymphocytes suggesting viral infection. Diagnosis: viral hepatitis (Serology was positive for Hepatitis A). Question 3: This was a 78 year old man with weight loss, who had had a total gastrectomy three years previously. Significant findings were a marked elevation of LD (in this case, a result of malignancy), and elevation of the alkaline phosphatase and gamma-glutamyltransferase (both biliary tract enzymes). The CT scan of the liver showed hepatic metastases. Diagnosis: metastatic carcinoma in the liver originating from a gastric carcinoma. DOUGLASS HANLY MOIR PATHOLOGY ABN 80 003 332 858 A subsidiary of SONIC HEALTHCARE LIMITED BARRATT & SMITH PATHOLOGY A trading name of DOUGLASS HANLY MOIR PATHOLOGY PTY LTD ABN 80 003 332 858 A subsidiary of SONIC HEALTHCARE LIMITED 95 EPPING ROAD MACQUARIE PARK NSW 2113 AUSTRALIA TEL 98 555 222 FAX 9878 5077 MAIL ADDRESS LOCKED BAG 145 NORTH RYDE NSW 1670 AUSTRALIA 31 LAWSON STREET PENRITH NSW 2750 AUSTRALIA TEL 4734 6500 FAX 4732 2503 MAIL ADDRESS PO BOX 443 PENRITH NSW 2751 AUSTRALIA