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  Liver Function Tests ( Common Blood Tests in Liver Disease)
  Liver Function Tests ;

a breakdown of what an LFT (Liver Function Test) may include, what it does, normal values, and what other than normal values can mean. Also drugs and other things that can affect the results of each test.

Liver function tests: defining what's normal

Your doctor can see how well your liver is working by testing your blood. The most common tests that are used to check how well your liver is working and your biliary system (the tubes that lead out of the liver) are called Liver Function Tests (LFT's). When your liver is working well, the levels are low. When your liver is not working as well as it should, they can become much higher. These substances include chemicals that your liver uses to do its work (called liver enzymes) and bilirubin (pronounced "billy-ru-bin"). Albumin (pronounced "al-byoo-men") is a protein made by the liver.

Your doctor may also order a liver panel, which generally includes the following tests:

ALT/SGPT: Alanine Aminotransferase
AST/SGOT: Aspartate Aminostransferase
AlkP: Alkaline Phosphatase
TBil: Total Bilirubin
DBil: Direct Bilirubin
Q   What does "elevated enzymes of the liver" mean?
A   The answer depends on many things. There are four liver enzymes that are commonly measured:

The ALT, AST, and GGT are transaminases that participate in metabolism. Their elevation suggests damage or inflammation of the liver itself. This occurs in response to infection in the liver or bile ducts (these drain the liver), hepatitis, and reactions to certain drugs and poisons (especially important with tylenol overdose, certain cholesterol lowering drugs, and some mushrooms).

The alkaline phosphatase is another enzyme, and it is predominately elevated when the liver drainage is obstructed. This occurs with gallstones in the bile ducts, and tumors of the liver, bile ducts, and pancreas.

Finally, although not an enzyme, the bilirubin is often measured. Bilirubin is a metabolic end product of decayed red blood cells. It is cleared by the liver. An increased bilirubin is an indicator that the liver, as a whole, is not functioning correctly. Accumulation of this substance in the blood is responsible for the jaundice seen in patients with liver disease

 
                         
 
NAME AFP (Alpha-fetoprotein)
NORMAL RANGE 0-8.9 ng/ml
DEFINITION This is a protein that is often used as a tumor marker for liver cancer. AFP is not normally present in healthy adults, other than pregnant women.
EXPLANATION
OF TEST
RESULT		 High levels may mean active liver disease. This test is also used for detection of liver cancer  (hepatocellular cancer)..
 
NAME Alb (Albumin)
NORMAL RANGE 3.3-5.2 mg/dl
DEFINITION This is the major protein in the blood, made only by the liver. It makes up the largest part of the Total Protein level. It maintains the fluid balance in your body.
EXPLANATION
OF TEST
RESULT		 A low level may mean advanced liver disease, because the liver is not able to produce the normal amount. Low levels may also be due to malnutrition, kidney disease or bowel and intestinal disease.
 
NAME AlkP (Alkaline phosphatase)
NORMAL RANGE 40-125 U/L
DEFINITION This is an enzyme made in the liver's bile ducts, bone, kidney and intestine.
EXPLANATION
OF TEST
RESULT		 High levels mean more advanced liver disease, especially problems with the liver's bile ducts. Levels can also be high if there is bone disease.
 
NAME ALT/SGPT (Alanine Aminotransferase)
NORMAL RANGE 7-56 U/L
DEFINITION This is an enzyme made in liver cells. If liver cells are damaged or die, ALT leaks out into the bloodstream.
EXPLANATION
OF TEST
RESULT		 This is the most important test to follow in a person with liver disease. A high ALT may mean a high degree of liver cell damage. However, ALT levels can also vary, and do not always reflect the degree of liver cell damage. A liver cell biopsy will give the most accurate information. The ALT enzyme is a more accurate marker of liver damage than the Ast enzyme. One goal of treatment for hepatitis C is a normal ALT level.
 
NAME Antibody
DEFINITION This is a protein developed by your body that protects you from an antigen.
 
NAME Anti-HBs (hepatitis B surface antibody)
EXPLANATION
OF TEST
RESULT		 If this test is positive, you have antibodies against the hepatitis B virus. You are likely to be immune (or protected) against the hepatitis B virus.
 
NAME Anti-HBc (hepatitis B core antibody)
EXPLANATION
OF TEST
RESULT		 If this test is positive, you have developed an antibody to the core of the virus and have been exposed to the hepatitis B virus. You may be currently infected, were infected and fought it off, have chronic infection or a false positive test.
NAME Anti-HCV (hepatitis C antibody)
EXPLANATION
OF TEST
RESULT		 If this test is positive, you may be infected with hepatitis C virus. This test does not tell whether you were exposed and fought off the infection, have chronic infection or if it is a false positive test. Another test called RIBA (recombinant immunoblot assay) may be used to confirm the hepatitis C antibody test result.
 
NAME Antigen
DEFINITION The antigen is the part of the virus that signals your body to protect itself.
 
NAME AST/SGOT (Aspartate Aminotransferase)
NORMAL RANGE 5-35 U/L
DEFINITION This is an enzyme made in liver cells, similar to the ALT. It is also made in muscles, and can be released from damaged muscle, heart, kidney, and brain tissue. Therefore, the AST level can be affected by many conditions other than liver disease.
EXPLANATION
OF TEST
RESULT		 Elevated levels can mean liver damage. Often the AST and ALT levels will elevate at the same time.
 
NAME Basophils
NORMAL RANGE 0.01-0.20 K/µl
DEFINITION These are white blood cells that are similar to Neutrophils.
 
NAME CBC(Complete Blood Count)
NORMAL RANGE See specific tests RBC HGB WBC and Platelets
DEFINITION A CBC tests for all the blood cells, including red blood cells and the different types of white blood cells.
 
NAME Cholesterol
NORMAL RANGE 100-240 mg/dl
DEFINITION Cholesterol is synthesized in the liver. It helps to build hormones, vitamins and cell membranes.
EXPLANATION
OF TEST
RESULT		 High levels of cholesterol are associated with atherosclerosis and heart disease. Low levels are a marker of poor liver function.
 
NAME CREAT (Creatinine)
NORMAL RANGE 0.6-1.4 mg/dl
DEFINITION This is a breakdown product of creatinine phosphate, which is a protein found in muscle. It is made entirely by the kidneys.
EXPLANATION
OF TEST
RESULT		 Abnormal levels usually indicate problems with the kidneys or renal system.
 
NAME Eosinophils
NORMAL RANGE 0.04-0.50 K/µl
DEFINITION These are white blood cells that are similar to Neutrophils.
 
 
NAME Ferritin
NORMAL RANGE 29-300 µg/L
DEFINITION This protein stores iron in the liver.
EXPLANATION
OF TEST
RESULT		 Primary storage form of iron in the body. High levels may mean liver disease or hemochromatosis.
 
NAME Genotype
DEFINITION The genotype is a mixture of genes within a virus. Genotypes help determine the genetic character of the viruses, such as the hepatitis C virus. Currently, there are six known hepatitis C genotypes.
 
NAME GGT (Gamma-glutamyltranspeptidase)
NORMAL RANGE 7-64 U/l
DEFINITION This is an enzyme made in the bile ducts. High levels may mean problems with the liver's bile ducts.
EXPLANATION
OF TEST
RESULT		 GGT is a very sensitive test, and can elevate if you use drugs or alcohol.
 
NAME Globulin
NORMAL RANGE 1-2.8 g/dl
DEFINITION These proteins and albumin make up Total Protein.
EXPLANATION
OF TEST
RESULT		 Levels of these proteins may vary in liver disease.
 
NAME HBeAg (hepatitis B e antigen)
EXPLANATION
OF TEST
RESULT		 If you test positive, you are currently infected and probably have high levels of hepatitis B virus in your blood. You may be very infectious to others.
 
NAME HBsAg (hepatitis B surface antigen)
EXPLANATION
OF TEST
RESULT		 If you test positive, you are currently infected with hepatitis B.
 
NAME HCT (Hematocrit)
NORMAL RANGE 42-52%
DEFINITION This measures the percentage of red blood cells per volume of blood sample.
EXPLANATION
OF TEST
RESULT		 Low levels may mean anemia. With anemia, hemoglobin may also be low.
 
NAME Hgb(Hemoglobin)
NORMAL RANGE 14-18 g/dl
DEFINITION This is a protein portion of red blood cells that carries oxygen.
EXPLANATION
OF TEST
RESULT		 Low levels may mean anemia, which is a common side effect of ribavirin treatment.
 
NAME INR (International normalized ratio)
DEFINITION This is a system of reporting the results of blood clotting tests.
EXPLANATION
OF TEST
RESULT		 In the INR system, results of blood clotting tests are standardized so health care providers all over the world are able to read the results.
 
NAME Iron
DEFINITION This is a mineral that plays a role in hemoglobin formation.
EXPLANATION
OF TEST
RESULT
  • % Iron Saturated in Blood: Measures overall percentage of iron in blood. Normal range is 16-60%.

     
  • Serum Iron: Measures level of iron in blood and is used to test for both low iron and iron overload, such as hemochromatosis. Normal range is 50-150 µg/dl.

 

NAME LYMPHS(Lymphocytes)
NORMAL RANGE 0.8-3.5 K/µl
DEFINITION These are white blood cells that produce antibodies to fight viral infections.
 
NAME Monocytes
NORMAL RANGE 0.2-0.8 K/µl
DEFINITION These are WBC that destroy foreign bacteria and other matter.
 
NAME NEUTS (Neutrophils)
NORMAL RANGE 2.2-8.6 K/µl
DEFINITION These are WBC that play a key role in inflammation, allergic reactions, pus formation, and in destroying bacteria and parasites.
EXPLANATION
OF TEST
RESULT		 Low neutrophil can mean infection or inflammation. Interferon treatment is associated with low neutrophil levels. Therefore, you must have normal levels of neutrophils to start interferon.
 
 
NAME Platelets
NORMAL RANGE 140-400 /mm3
DEFINITION These are small blood cells that helps blood clot when injury occurs.
EXPLANATION
OF TEST
RESULT		 May be low in advanced liver disease, or while on interferon treatment. A low count may increase the chance of bleeding. Therefore, you must have normal levels of platelets to start interferon treatment.
 
NAME Polymerase Chain Reaction (PCR)
DEFINITION This is a test that can detect the hepatitis C virus. Examples of this test include the following:
EXPLANATION
OF TEST
RESULT(S)
  • Qualitative PCR: tests for presence of virus. Result is given as "positive" or "negative".

     
  • Quantitative PCR: tests for amount of virus (viral load). The viral loads are often expressed in international units so that the values obtained by different test methods can be compared. The result is given as an actual number (for example, number of virus particles per milliliter of blood).
 
NAME Protein, total
NORMAL RANGE 6.0-8.5 g/dl
DEFINITION Total protein includes large particles in the blood made of albumin and globulins.
EXPLANATION OF TEST
RESULT		 Low levels of total protein indicate a more advanced stage of liver disease.
 
 
NAME PT (Prothrombin Time)
NORMAL RANGE 9.8-13.8 seconds
DEFINITION This is a measure of the time that it takes for your blood to clot. Prothrombin is a protein that is changed to thrombin during clotting.
EXPLANATION OF TEST
RESULT		 High PT may mean advanced liver disease. It may also be high if you are taking coumadin (warfarin) for a heart condition, or if you have a vitamin K deficiency.
 
NAME PTT (Partial Thromboplastin Time)
NORMAL RANGE 24.2-36.0 seconds
DEFINITION This is another measure of clotting time.
EXPLANATION
OF TEST
RESULT		 In addition to PT, this result shows if blood is clotting at a normal time. It is higher than normal in people with clotting disorders or patients on certain medicines, such as heparin.
 
NAME Quasispecies
DEFINITION When the virus changes and makes copies, it can make errors. This leads to minor genetic differences in viruses in an individual infected with a single genotype.
 
NAME RBC(Red Blood Cells)
NORMAL RANGE 4.7-6.1 /mm3
DEFINITION These are small cells that carry oxygen in the blood.
EXPLANATION
OF TEST
RESULT		 Lab values show over- or under-production. Low levels may mean anemia.
 
NAME RIBA™ (recombinant immunoblot assay)
DEFINITION This is a more specific test than the hepatitis C antibody test, that helps confirm a diagnosis of hepatitis C virus infection.
 
 
NAME T3, total
NORMAL RANGE 45-137 ng/dl
DEFINITION T3 is a form of thyroid hormone.
EXPLANATION
OF TEST
RESULT		 T3 levels may be abnormal in liver disease.
 
NAME T4, free
NORMAL RANGE 9-24 pmol/l
DEFINITION T4 is a form of thyroid hormone.
EXPLANATION
OF TEST
RESULT		 T4 levels may be abnormal in liver disease.
 
NAME TBili (bilirubin, total)
NORMAL RANGE 0.1-1.2 mg/dl
DEFINITION TBili is a breakdown product from hemoglobin in old red blood cells. Usually, it is removed from the blood by the liver, broken down, and sent to the intestines through the bile ducts.
EXPLANATION
OF TEST
RESULT		 High levels mean liver damage, or blockage in the ducts (tubes) of the liver. High levels also cause yellowing of the skin and whites of the eyes (called jaundice).
 
NAME Triglycerides
NORMAL RANGE 10-190 mg/dl
DEFINITION These are fatty substances in the blood.
EXPLANATION
OF TEST
RESULT		 Triglyceride levels may become high during interferon treatment. Levels usually return to normal after treatment has stopped.
NAME TSH (Thyroid Stimulation Hormone)
NORMAL RANGE 0.4-6.0 µIU/ml
DEFINITION This hormone causes other thyroid hormones (T3 and T4) to be produced. Thyroid hormones help the body function, and metabolize foods.
EXPLANATION
OF TEST
RESULT		 High levels of TSH are associated with interferon treatment and hypothyroidism.
NAME WBC(White Blood Cells)
NORMAL RANGE 4.8-10.8 /mm3
DEFINITION This test measures the overall number of white blood cells. There are five types of WBC: Neutrophils, eosinophils, basoph, Monocytles and Lymphocytes. Each of them does slightly different jobs. All of them are used for fighting infections. White blood cells are made in the bone marrow.
 
 
EXPLANATION
OF TEST
RESULT		 Low WBC may mean bone marrow depression, a common side effect of interferon treatment. Low levels can also be caused by reactions to toxins, or to the presence of a virus.

                        

 

 
   
 

Liver Function Test
(LFT)

Here is a breakdown of what an LFT (Liver Function Test) may include, what it does, normal values, and what other than normal values can mean. Also drugs and other things that can affect the results of each test.
 

The typical Liver Profile test includes:
 Bilirubin
 Protein
 LDL
 Alkaline Phosphatase
 SGOT/AST (aspartate amino transferase)
 SGPT/ALT (amino alanine transferase)
 Albumin
 Globulin

BLOOD BILIRUBIN:
Test evaluates liver function and the condition of red blood cells. Diagnoses jaundice. Monitors progression of jaundice. Helps confirm diagnosis of obstruction of the bile ducts. Helps diagnose cause of anemia.
Normal Values:
 Adult indirect bilirubin levels--1.1 mg/dl or less
 Adult direct bilirubin levels--Less than 0.5 mg/dl
 Total bilirubin in a newborn--1 to 12mg/dl

bullet What "high" or "increased" may indicate:
 Congenital enzyme deficiencies (Gilbert's disease)
 Liver damage
 Severe hemolytic anemia
 Obstruction of bile ducts from stones or tumors
 If over 20mg/dl in a newborn, exchange transfusion may be needed.

Taking these drugs may affect test results:
Aminophenol, Anti-malarials, Ascorbic acid, Dextran, Epinephrine, Ethoxazene, Histidine, Indican, Isoproterenol, Levodopa, Methyldopa, Novobiocin, Phenazopyridine, Phenelzine, Primaquine, Rifampin, Streptomycin, Sulfa drugs, Theophylline, Tyrosine

BLOOD PROTEIN ELECTROPHORESIS (PROTEIN, ALBUMIN, GLOBULIN):
Purpose of the test is to help confirm blood disorders, gastrointestinal disorders, kidney disorders, liver disease, protein deficiency, diagnosis of tumors.

Normal values:
 Protein--6.6 to 7.9g/dl
 Albumin fraction--3.3 to 4.5g/dl
 Alpha-1-globulin fraction--0.1 to 0.4g/dl
 Alpha-2-globulin ranges--0.5 to 1g/dl
 Beta globulin--0.7to 1.2g/dl
 Gamma globulin--0.5 to 1.6g/dl


What "high" or "increased" may indicate:
 Chronic inflammatory disease
 Chronic syphilis
 Collagen diseases
 Dehydration
 Diabetes mellitus
 Diabetic acidosis
 Early-stage Laennec's cirrhosis
 Fulminating and chronic infections
 Hodgkin's disease
 Monocytic leukemia
 Multiple myeloma
 Rheumatoid arthritis
 Subacute bacterial endocarditis
 Systemic lupus erythematosus
 Tuberculosis
 Vomiting and diarrhea

What "low" or "decreased may indicate:
 Acute cholecystitis
 Benzene and carbon-tetracholoride poisoning
 Blood dyscrasias
 Collagen diseases
 Congestive heart failure
 Diarrhea
 Diabetes mellitus, uncontrolled
 Essential hypertension
 Gastrointestinal disease
 Hemorrhage
 Hepatic disease
 Hepatic dysfunction
 Hodgkin's disease
 Hyperthyroidism
 Hypogammaglobulinemia
 Malabsorption
 Malnutrition
 Metastatic carcinoma
 Neoplastic and renal diseases
 Nephritis
 Nephrosis
 Peptic ulcer
 Plasma loss from burns
 Rheumatoid arthritis
 Sarcoidosis
 Surgical or traumatic shock
 Systemic lupus erythematosus
 Toxemia of pregnancy

Taking these drugs may affect test results:
Cytotoxic agents, Cytotoxin, Cyclosporin

Other factors that may affect test results:
 Pregnancy
 Contrast dyes, such as sulfobromophthalein

BLOOD (SERUM) GLUTAMIC-OXALOACETIC TRANSAMINASE (SGOT)
Purpose of the test:
 Helps diagnose recent severe heart problem
 Helps detect and differentiate between varying forms of liver disease

Normal values:
 Test values are more meaningful when correlated with test results for creatine phosphokinase and lactic dehydrogenase. Values fluctuate and may be transiently and minimally elevated during early phases of heart attack.

 A rising level over several days means continuing damage
 A decreasing level over several days means tissue repair
 8 to 20u/liter
 Normal values for infants are 4 times higher than those of adults

What "high" or "increased" may indicate:
 Acute pancreatitis
 Acute viral hepatitis
 Alcoholic cirrhosis
 Chronic hepatitis
 Delirium tremens
 Dermatomyositis
 Drug-inducted liver injury
 Duchenne muscular dystrophy
 Extensive recent surgery
 Fatty liver
 Hemolytic anemia
 Metastatic hepatic tumor
 Pulmonary embolism
 Severe infectious mononucleosis
 Severe muscle trauma
 Severe myocardial infarction
 Severe passive liver congestion

Taking these drugs may affect test results:
Acetaminophen (large doses), Anti-tubercular agents, Chlorpropamide, Dicumarol, Erythromycin, Methyldopa, Opiates, Pyridoxine, Salicylates, Sulfonamides, Vitamin A

Other factors that may affect test results:
 Strenuous exercise
 Muscle trauma
 Failure to fast overnight

BLOOD GLUTAMIC-PYRUVIC TRANSAMINASE (SGPT)

Purpose of the test:
 Helps detect and evaluate treatment of acute hepatic disease
 Helps distinguish between myocardial and hepatic-tissue damage

Normal values:
 Men--10 to 32 u/liter
 Women--9 to 24u/liter
 Infants--Twice normal range of adults

What "high" or "increased" may indicate:
 Severe hepatitis
 Chronic hepatitis
 Early or improving acute viral hepatitis
 Infectious mononucleosis
 Intrahepatic cholestasis
 Cholecystitis
 Severe hepatic congestion due to heart failure
 Slight to moderately high levels may indicate any condition that produces acute hepatocellular injury.

Taking these drugs may affect test results:
Barbiturates, Chlorpromazine, Codeine, Griseofulvin, Isoniazid, Meperidine, Methyldopa, Morphine, Narcotic analgesics, Nitrofurantoin, Para-aminosalicylic acid, Phenothiazines, Phenytoin, Salicylates, Tetracycline

Other factors that may affect test results:
 Eating lead
 Exposure to carbon tetrachloride
 Failure to fast overnight
 If tourniquet is applied on the arm too long (over 1 minute), it may cause an inaccurate test result. Request another sample to be collected to ensure accuracy.

ALKALINE PHOSPHATASE:
Purpose of test:
 Detects and identifies skeletal disease, especially diseases characterized by rapidly growing bone.
 Detects liver diseases causing obstructions, such as a tumor or abscess.
 Assesses response to vitamin D in treating rickets caused by vitamin-D deficiency.

Normal values:
(Alkaline phosphatase levels measured by chemical inhibition range from):
 Men--90 to 239u/liter
 Women (under age 45)--76 to 196u/liter
 Women (over age 45)--87 to 250u/liter
 Children normally have levels up to 3 times higher than adults

What "high" or "increased" may indicate:
 Acute or complete biliary obstruction
 Deficiency-induced rickets
 Osteomalacia
 Extensive bone metastases
 Hyperparathyroidsm
 Paget's disease

What "low" or "decreased" may indicate:
 Hypophosphatasia
 Protein deficiency
 Magnesium deficiency

Taking these drugs may affect test results:
Albumin, Barbiturates, Chlorpropamide, Halothane, Isoniazid, Methyldopa, Oral contraceptives, Phenothiazines, Phenytoin, Rifampin

Other factors that may affect test results:
 Healing long-bone fractures
 Age (infants, children, adolescents, women over 45)
 Failure to fast overnight
 If tourniquet is applied on the arm too long (over 1 minute), it may cause an inaccurate test result. Request another sample be collected to ensure accuracy.

ANTI-NUCLEAR ANTIBODIES (ANA):
Purpose of test:
 Screens for systemic lupus erythematosus
 Screens for several autoimmune disorders
 Monitors effectiveness of treatment with drugs for systemic lupus erythematosus

Normal values:
 Test for Ana is negative at a titer of 1:32 or below

What absence of ANA may indicate:
 Rules out systemic lupus erythematosus

What low titers may indicate:
 Viral diseases
 Liver disease
 Collagen-vascular disease
 Autoimmune disease

Taking these drugs may affect test results:
Acetazolamide, Aminosalicylic acid (PAS), Chlorothiazide, Chlorpromazine, Chlorprothixene, Clofibrate, Ethosuximide, Gold salts, Griseofulvin, Hydralazine, Isoniazid, Mephenytoin, Methyldopa, Methysergide, Oral contraceptives, Para-aminosaalicylic acid, Penicillin, Phenylbutazone, Phenytoin, Primidone, Procainamide, Propylthiouracil, Wuinidine, Reserpine, Streptomycin, Sulfonamides, Tetracyclines, Thiouracil, Trimethadion

Other factors that may affect test results:
 If tourniquet is applied on the arm for too long (over 1 minute), it may cause an inaccurate test result. Request another sameple to be collected to ensure accuracy.

GAMMA GLUTAMYL TRANSFERASE (GGT):
Purpose of test:
 Provides information about liver disease
 Assesses liver function
 Distinguishes between bone-and-joint disease and liver disease when blood alkaline-phosphatase levels are elevated.

Normal values:
 Men--6 to 37u/liter
 Women under 45--5 to 27u/liter
 Women over 45--6 to 37u/liter

What "high" or "increased" may indicate:
 Acute liver disease
 Acute pancreatitis
 Epilepsy
 Brain tumor
 Prostatic metastasis
 Renal disease
 Hepatic metastatic infiltrations
 Obstructive jaundice
 Possibly following myocardial infarction

Taking these drugs may affect test results:
Aminoglycosides, Barbiturates, Clofibrate, Oral contraceptives, Pehnytoin

Other factors that may affect test results:
 Moderate intake of alcohol causes increased blood-GGT levels that may last for at least 60 hours.
 Failure to fast overnight
 If tourniquet is applied on the arm too long (over 1 minute), it may cause an inaccurate test result. Request another sample to be collected to ensure accuracy.

ISOCITRATE DEHYDROGENASE (ICD):
Purpose of the test:
 Provides important information to assess presence and extent of liver damage
 Detects early viral hepatitis and infectious mononucleosis
 Distinguishes between liver disease and myocardial infarction when SGOT is elevated

Normal values:
 Plasma-ammonia levels are less than 50mcg/dl

What "high" or "increased" may indicate:
 Bleeding from the gastrointestinal tract
 Congestive heart failure
 Erythroblastosis fetalis
 Reye's syndrome
 Sever liver disease leading to hepatic coma

Taking these drugs may affect test results:
Acetazolamide, Ammonium salts, Furosemide, Danamycin, Lactulose, Neomycin, Thiazides

Other factors that may affect test results:
 Portacaval shunt
 Hyperalimentation
 If tourniquet is applied on the arm too long (over 1 minute), it may cause an inaccurate test result. Request another sample to ensure accuracy.

PLASMA THROMBIN TIME (THROMBIN CLOTTING TIME):
Purpose of the test:
 Detects fibrinogen deficiency or defect
 Helps confirm diagnosis of DIC and liver disease
 Monitors effectiveness of heparin, streptokinase, or urokinase treatment

Normal values:
 Thrombin times range from 10 to 15 seconds. Test results are usually reported with a normal-control value.

What "high" or "increased" may indicate:
 Dysfibrinogenemia
 Effective heparin therapy
 Liver disease
 Hypofibrinogenemia
 If DIC is suspected, an additional test for fibrin split products is also necessary

Taking these drugs may affect test results:
Anti-coagulants, Heparin

Other factors that may affect test results:
If tourniquet is applied on the arm too long (over 1 minute), it may cause an inaccurate test result. Request another sample to be collected to ensure accuracy.

AST, ALT, GGTP, AP
 

What do these letters mean?
These letters are acronyms for enzymes - proteins inside of cells. AST for example stands for aspartate amino transferase. This enzyme used to be called serum glutamic oxalacetic transaminase (SGOT), hence the two names. ALT = amino alanine transferase, GGTP= gamma glutamyl transpeptidase, and AP= alkaline phosphatase. Different cells have different enzymes inside them, depending on the function of the cell. Liver cells happen to have lots of AST, ALT, and GGTP inside them. When cells die or are sick the enzymes leak out causing the blood level of these enzymes to rise, which is a way of determining if the cells in question are sick. ALT is more specific for liver disease than AST because AST is made in more places (e.g. heart, intestine, muscle). So the AST will rise after a heart attack or bruised kidney. GGTP and AP are said to be more specific for biliary disease since they are made in bile duct cells. In liver disease caused by excess alcohol ingestion, the AST tends to exceed the ALT, while the reverse is true to for viral hepatitis. However, this particular generalization is often wrong.

Some points:
•These tests have meaning, but they generally cannot be interpreted without clinical information. They are probably most useful to track, or follow a particular problem, but even then they often "bounce around" greatly.
•These numbers are not linear. An AST that is 300 is not twice as bad as 150 (normal is less than 50). We are used to numbers like temperature and dollars. If it is 94 degrees F outside, it is warmer than if it is 80 every time. And if one has 94 dollars, one has more money than if one has 80. Liver enzyme values don't behave this way. An AST of 94 and 80 are essentially the same to a liver specialist.
•These numbers do not always detect all liver disease. Some very patients with severe advanced liver disease will have normal or nearly normal enzyme levels.

Are these numbers indicative of liver function?
Not really. Unfortunately, they are often called "liver function tests" or "LFT's", but in actuality, they do not measure function per se.

Then how is liver function measured?
Other tests including albumin, bilirubin, and prothrombin time are more truly measures of function, but clinical factors must be considered as well.

BMJ 2004;328:987 (24 April), doi:10.1136/bmj.328.7446.987
Commentary

Liver function tests: defining what's normal

Paul Roderick, senior lecturer in public health1
1 Community Clinical Sciences Research Division, University of Southampton,
B Floor, South Academic Block, Southampton General Hospital, Southampton
SO16 6YD

Correspondence to: P Roderick pjr@soton.ac.uk

Chronic liver disease and hepatocellular carcinoma are major worldwide
public health problems in countries with endemically high levels of viral
hepatitis (B and C).1 However, even in western countries chronic liver
disease is an emerging problem, due not only to viral hepatitis but also to
the effects of lifestyle factors such as heavy alcohol consumption and
obesity.2 3

Liver function tests are widely performed blood tests used in patients with
suspected liver disease or unexplained illness and in some specific
situations such as screening of blood donors. The most widely used tests are
those used to detect the aminotransferases—alanine and aspartate—which are
associated with hepatocellular injury. Raised concentrations may indicate
serious underlying chronic liver disease, recognition of which is important
for guiding interventions to modify lifestyle and use of specific therapies
such as interferon for hepatitis C to prevent the risk of progression to
cirrhosis.

The sensitivity, specificity, and predictive values are important in
assessing the clinical utility of such tests. Normal ranges have been based
on distributions from healthy volunteers with two SD above the mean (that
is, top 2.5% cut-off) being considered the upper normal range.
Aminotransferase concentrations maybe within the normal range in people with
chronic liver disease.4 5 There is ongoing debate about whether to lower the
normal range to take account of changing lifestyle factors that influence
aminotransferase concentrations, particularly obesity, which in Western
countries would increase the detection of hepatitis C and alcoholic and
non-alcoholic fatty liver disease (NAFLD).6 7

Kim and colleagues have analysed the association between aminotransferase
concentrations and mortality from liver disease in a large prospective
cohort in Korea.1 They found that there was a graded increase in risk of
mortality from liver disease even within the normal range (20-40 IU/l)
compared with the lowest concentrations (< 20 IU/l) for both sexes. The
performance of the test in identifying future risk of mortality from liver
disease was maximised by lowering the threshold to about 30 IU/l. They
propose identifying a borderline level of aminotransferase of 30-39 IU/l,
suggesting that patients in this category should be further investigated
with more specific diagnostic tests for chronic liver disease.

What are the implications for countries with lower levels of chronic liver
disease than Korea? Test utility is affected by disease prevalence. In
countries with lower prevalence the negative predictive value (that is, the
ability of a negative test to exclude disease) will be higher and the
positive predictive value (that is, the ability of a positive test to
predict disease) will be lower. Lowering the upper normal range for
aminotransferase or including borderline cases will increase sensitivity at
the expense of specificity, so detecting more cases of chronic liver disease
but with a lower positive predictive value. These effects would be less
marked in those with suspected liver disease compared with the population as
whole. The cost effectiveness of further investigation of borderline cases
is not known but requires evaluation. A crucial diagnostic issue is how to
identify severe chronic liver disease (indicated by inflammation and
fibrosis), which is associated with high risk of progressing to cirrhosis.
Definitive evaluation currently relies on liver biopsy. Research is needed
to evaluate combinations of non-invasive measures to predict severe liver
disease; this could include patients with borderline concentrations of
aminotransferase.

--------------------------------------------------------------------------------
Competing interests: Research collaboration with Bayer Health-Care.
References

Kim HC, Nam CM, Jee SH, Han KH, Oh DY, Suh I. Normal serum aminotransferase
concentration and risk of mortality from liver disease: prospective cohort
study. BMJ 2004 doi/10.1136/bmj.38050.593634.63
Clark JM, Brancati FL, Diehl AM. The prevalence and etiology of elevated
aminotransferase levels in the United States. Am J Gastroenterol 2003;98:
960-7.[CrossRef][ISI][Medline]
Department of Health. On the state of the public health. The annual report
of the chief medical officer. London: Department of Health: 2002.
Kyrlagkitsis I, Portmann B, Smith H, O'Grady J, Cramp ME. Liver histology
and progression of fibrosis in individuals with chronic hepatitis C and
normal elevated ALT. Am J Gastroenterol 2003;98: 1588-93.[ISI][Medline]
Pratt DS, Kaplan MM. Evaluation of abnormal liver-enzyme results in
asymptomatic patients. N Engl J Med 2000;342: 1266-71.[Free Full Text]
Prati D, Taioli E, Zanella A, Della Torre E, Butelli S, del Vecchio E, et
al. Updated definitions of healthy ranges for serum alanine aminotransferase
levels. Ann Intern Med 2002;137: 1-9.[Abstract/Free Full Text]
Kaplan MM. Alanine transferase levels: what's normal. Ann Intern Med
2002;137: 49-50.[Free Full Text]
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  Page Two:

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