Clinical Biochemistry of Liver Disease Liver Function Tests & Clinical Biochemistry of Liver Disease Mohamad Nusier MD. PhD.

Illustrative case History 75 yr old female presented to her GP C/O dyspepsia and “back “ pain Background hx: Breast Ca – Rx with mastectomy, Tamoxifen Variegate Porphyria Type 2 Diabetes mellitus Subclinical Hypothyroidism GP requested Liver Function Tests (Liver Profile)

Albumin 43 (34-48) g/L Total Bilirubin 7 (0 – 21) umol/L Alkaline Phosphatase 67 (35 -104) IU/L GGT 93 (5 – 36) IU/L Alanaine transaminase (ALT) 40 (6 – 31) IU/L

In view of abnormal LFTs the GP ordered further investigations Anti Smooth Muscle Abs (ASMA) - negative Anti Mitochondrial Abs (AMA) - negative Alpha-1 Antitrypsin 1.5 (0.9 – 2.0) g/L Caeuroloplasmin 26.2 (20 – 60) mg/dl Transferrrin Saturation 34% (15 – 45) % PT 14.8 (11.5 – 15.0) s APTT 30.4 s (25 – 35) s APTT: activated partial thromboplastin time

GP requested imaging studies in view of negative blood tests Ultrasound of abdomen and pelvis Liver Diffuse inhomogenous somewhat echogenic texture No focal lesion Bile ducts not dilated CT scan of abdomen Normal size Subcapsular surface of the liver has a nodular outline Liver texture has a diffuse slightly coarse appearance Appearances consistent with Cirrhosis

Learning Point The only indicator for the presence of underlying cirrhosis in this patient were her mildly abnormal LFTs Pay attention to minor abnormalities!

What are the functions of the liver? Key role in intermediary metabolism e.g. gluconeogenesis, glycolysis, ketogeneis, lipid synthesis Protein synthesis – including many plasma proteins and blood clotting factors Bile secretion and role in digestion Primary site of xenobiotic detoxification -drug and toxin metabolism Ureagenesis - ? Role in acid-base balance

What are Liver Function Tests (LFTs) Total Bilirubin Conjugated vs. Unconjugated Alkaline Phosphatase (ALP) -Reference range varies with age – higher in childhood and adolescence Isoenzymes e.g. bone, liver, intestine, malignancy Bile flow Gamma-glutamyl transferase (GGT) -Sensitive indicator of liver disorder -Cholestasis -Induced by many drugs and toxins e.g. C2H5OH, pheytoin, barbiturates, ? statins

Transaminases -Alanine aminotransferase (ALT) -Aspartate aminotransferase (AST) -ALT is more liver specific -AST is also found in cardiac and skeletal muscle -Hepatocellular integrity Albumin - Plasma transport protein Assesses Protein synthesis in liver Prothrombin time Extrinsic pathway of coagulation Reflects protein synthetic function

What role do LFTs in clinical management ? Detecting the presence of liver disease Indicating the broad diagnostic category of the liver disease Monitoring treatment

Specialised Liver-related tests Viral Hepatitis Screen – A, B, C etc. Autoimmune Heptitis screen – AMA (antimitochondrial antibody), ASMA (Antismooth muscle antibodies) Serum protein electrophoresis α1- antitrypsin α fetoprotein (AFP) Transferrin Saturation, Ferritin, HFE Genotyping (hereditary hemochromatosis) Ceruloplasmin, Plasma, Urine Copper Ultrasound scan, CT, MRI Biopsy

Clinical History C2H5OH Hx Family Hx – Hemochromatosis, Wilson Disease, Drug Hx – What medication is the patient taking? Travel Hx – Recent travel, Blood transfusions

Bilirubin production and metabolism UDP Glucoronosyl transferase

Hyperbilirubinaemia Jaundice evident with Bilirubin levels 35-70 μmol/L Normally 95% of plasma bilirubin is unconjugated Conjugated – Hepatic/posthepatic (Bilirubinuria) Hepatocellular diseases Cholestatic diseases Dubin-Johnson** Rotor’s syndrome** Unconjugated - prehepatic *(No bilirubinuria) Hemolysis Resolving hematoma Gilbert’s Syndrome Crigler-Najjar syndrome *Except in Nephrotic syndrome **Benign congenital conjugated hyperbilirubinemia

Gilbert’s Syndrome Present in 5% of the population Males > females Genetic origin – insertion of TA in promoter region of UGT-1A gene Exacerbated by fasting and illness Confirm unconjugated hyperbilirubinemia Rule out hemolysis CBC, Reticulocyte count Rule out underlying liver disease

Causes of neonatal jaundice Unconjugated bilirubin level > 300μmol/L may be associated with Kernicterus (brain damage due to uptake of unconjugated bilirubin)

Patterns of LFTs Hepatocellular Predominant elevation in AST/ALT ratio Both enzymes require pyridoxal-5'-phosphate (vitamin B6) in order to carry out this reaction, although the effect of pyridoxal-5'-phosphate deficiency is greater on ALT activity than on that of AST. This has clinical relevance in patients with alcoholic liver disease, in whom B6 deficiency may decrease ALT serum activity and contribute to the increase in the AST/ALT ratio that is observed in these patients Cholestatic Predominant elevation in ALP with GGT ± Bilirubin Mixed Elevation in both AST/ALT, and ALP/GGT ± Bilirubin

Marked elevations in ALT/AST > X5 Causes of a Hepatocellular Pattern of LFTs Marked elevations in ALT/AST > X5 (patient likely to be symptomatic) Viral hepatitis Ischaemic hepatitis Autoimmune hepatitis Drug/toxins e.g. alcoholic hepatitis

Causes of a Hepatocellular Pattern of LFTs Mild/Moderate elevations in ALT/AST < X5 (patient may be asymptomatic) Chronic Hepatitis ALD (Adrenoleukodystrophy), Beta Oxidation of fatty acids disorder NAFLD/NASH (Nonalcoholic fatty liver disease /Non-alcoholic steatohepatitis): associated with obesity, T2DM, Hyerlipidemia Metabolic liver disease: Hereditary hemochromatosis, Wilson Disease, Alpha-1 antitrypsin deficiency Drugs Autoimmune Liver Disease

Approach to an asymptomatic patient with elevated ALT/AST Elevated AST/ALT Repeat test ? Muscle problem Still Elevated Normal Check CK Elevated Normal Likely Liver Aetiology Drug Hx etc Viral serology AI hepatitis screen Fe/TIBC/Ferritin/HFE genotyping Caeuruloplasmin if < 40 yr A1AT Celiac screen Ultrasound scan MRI/CT Bx

Causes of a Cholestatic Pattern of LFTs Elevated ALP and GGT ± Bilirubin, relative to transaminases Extrahepatic (Bilirubin elevated) Cholelithiasis (CBD) Malignancy Primary sclerosing cholangitis Intrahepatic (Bilirubin not elevated) Medications TPN (Total Parenteral Nutrition) Sepsis Postoperative PBC (Primary Biliary Cirrhosis) Alcoholic hepatitis Liver metastasis Pregnancy-related CCF (Congestive Cardiac Failure) CBD: common bile duct; GGT is useful in differentiating Liver as a cause of elevated ALP

An approach to the patient with isolated elevation in ALP Elevated ALP Normal What is GGT? Elevated bone, placenta, Intestine etc. US/CT/MRI No abnormality Biliary dilation Focal mass Medications Consider other causes PBC -AMA Primary biliary cirrhosis (PBC) Anti-mitochondrial antibodies (AMA Specialized investigations

Other LFTs Serum ammonia used for investigation of hepatic encephalopathy -lacks sensitivity and specificity -useful for investigation of urea cycle disorders Serum LDH -included in LFTs -5 isoenzymes – heart, erythrocytes, skel mus, liver, others -not specific for liver? role in ischemia-related abnormal LFTs -useful in monitoring certain malignancies e.g. B-cell lymphoma - “not really a LFT”

Reference Ranges for LFTs Biochemistry Department, St James’s Hopsital Albumin 35-50 g/L Bilirubin <17 mmol/L ALP* 40-120 IU/L* AST 7-40 IU/L ALT 7-35 IU/L GGT 10-55 IU/L * NB: Reference Range is age related

Hepatic necrosis observed within 36-72 hours Paracetamol Overdose Hepatic necrosis observed within 36-72 hours Accumulation of breakdown product NAPQI NAPQI (N-acetyl-p-benzoquinone imine)

Early diagnosis and treatment of paracetamol OD is essential Ideally before 12 hours post ingestion N-acetylcysteine (Parvolex) is an effective agent