Liver Function Tests Flashcards
What are the LFT’s?
Total Protein Albumin Alkaline Phosphatase AST (SGOT) ALT (SGPT) LDH Bilirubin Total Direct Indirect
What is the total protein adult ri?
6.4 – 8.3 g/dl
What is the total protein children ri?
Newborn: 4.6 – 7.4 g/dl
Infant: 6 – 6.7 g/dl
Child: 6.2 – 8 g/dl
What are the indications for a total protein test?
Used to diagnose, evaluate and monitor following diseases:
Liver disease
Intestinal/renal protein wasting states
Immune disorders
Impaired nutrition
Chronic edematous states
What are the functions of protein?
Muscles Enzymes Hormones Transport substances Structural components of cell membrane Channels Osmotic pressure
What is the function of prealbumin?
Transports thyroxine
Where is albumin formed?
Liver
how much of the total protein is albumin?
60% of serum protein
What is the function of albumin?
Transports drugs, hormones & enzymes
What happens to protein levels in liver cell disease?
When liver cells diseased, they are unable to synthesize albumin and albumin level decreases. Because half life of albumin is 12-18 days, severe impairment of albumin synthesis may not be recognized for months.
What key proteins do globulins make up?
Antibodies, glycoproteins, lipid proteins, clotting factors and complement
What are the three types of globulins?
Alpha
Beta
Gamma
What molecules are alpha globulins present in?
Alpha1 antitrypsin, haptoglobin, prothrombin, cholinesterase
What molecules are beta globulins present in?
Lipoproteins, plasminogen, fibrinogen
What molecules are gamma globulins present in?
Immune globulins
What conditions exhibit increased gamma globulin levels?
- MM: gamma glob from neoplastic plasma cells.
- Chronic Inflamm Dis: RA, SLE; have asst autoantibodies.
- Malignancy: Hodgkins, lymphoma, leukemia
- Cirrhosis: pathophys not known.
- Acute or chronic Infection results in ab response
What conditions exhibit decreased gamma globulin levels?
- Genetic immune disorders
- Secondary immune deficiency
Steroid use
Nephrotic Syndrome
Leukemia
What are the adult ri for albumin?
3.5-5.0 g/dl
What are the childhood ri for albumin?
Newborn: 3.5-5.4 g/dl
Infant: 4.4-5.4 g/dl
Children: 4-5.9 g/dl
What are the indications for albumin testing?
Measure of nutritional status
Measure of hepatic function
Measure of renal function
Where is albumin synthesized?
Liver
Albumin is a major contributor of what kind of pressure?
Osmotic pressure
Albumin is important in the transport of what?
Fatty acids
Thyroid hormones
Steroid hormones
What happens to the albumin concentration in dehydration?
Increased albumin levels
What conditions are asst with decreased albumin levels?
- Malnutrition: lack of aa for building proteins; also liver dysfunction asst with malnutrition also contributes to low albumin levels.
- Pregnancy: increased demands on the body
- Hepatic disease: Hepatitis, cirrhosis, metastatic liver tumor
Liver: site of albumin synthesis. - Malabsorption: Crohns Disease
- Third space losses: ascitis, third degree burns
- Overhydration
What are the normal adult ri for alkaline phosphatase?
30-120 units/L
What are the normal elderly ri for alkaline phosphatase?
Slightly higher than adults
Adults 30-120units/L
What are the normal elderly ri for alkaline phosphatase?
Children (units/l) <2 yrs 85-235 2-8 yrs 65-210 9-15 yrs 60-300 16-21 yrs 30-200
What are the indications for alkaline phosphatase?
Detect and monitor diseases of Liver and Bone
Where are the highest concentrations of ALP?
- Liver and biliary tract epithelium: Kupffer cells
- Bone
A. Most frequent extrahepatic source of ALP
B. New bone growth = increased ALP levels
How do you distinguish between ALP from the bone and the liver?
ALP1 – Liver
ALP2 - Bone
What conditions are associated with increased ALP
- Primary cirrhosis
- Biliary obstruction
A. Intrahepatic
B. Extrahepatic - Liver tumor
A. Primary
B. Metatstatic - Normal bones of growing children
- Healing fracture
- Paget’s Disease
Aspartate Aminotransferase (AST) normal adult and elderly ri?
0–35 units/l
Aspartate Aminotransferase (AST) normal Childhood ri?
10-140 units/l
Highest in newborns
Lowest in adolescents (10-40 units/l)
What are the indications for AST testing?
Suspected occlusive coronary artery disease
Suspected hepatocellular disease
Where is AST found?
Found in metabolically active tissues Heart Liver Skeletal muscle Pancreas RBC’s Kidneys
If disease or injury in any of these cells
Cells lyse and release AST
What is AST level directly related to?
Number of cells injured
When is AST increased post injury?
Elevated 8 hours post injury
Peaks 24-36 hours post injury
Returns to normal in 3-6 days
Increased AST are asst with what cardiac conditions?
MI
Cardiac surgery
Cardiac catheterization
Angioplasty
Increased AST are asst with what hepatic conditions?
- Hepatitis
AST rises up to 20x normal (700 units/L) - Cirrhosis
Level depends on amount inflammation - Hepatic mets
- Infectious mono with hepatitis
Increased AST are asst with what skeletal muscle conditions?
Muscle trauma
Recent noncardiac surgery
Severe deep burns
Recent seizures
Increased AST are asst with what other conditions?
- Acute pancreatitis
- Acute extrahepatic obstruction
- Gallstone
- Level rises 10x normal
Decreased ASt levels are asst. with what conditions?
Acute renal disease
Chronic renal dialysis
What are Alanine Aminotransferase (ALT) ri for children, adults, and elderly?
4-36 units/l
What are the indications for ALT testing?
Hepatocellular disease
Identification
Monitoring treatment
Where is ALT normally found?
Found primarily in liver
Injury or disease affecting liver will cause
release of this enzyme
What test is ALT usually ordered with?
AST
What conditions are asst. with increased ALT?
Hepatitis Hepatic necrosis Cirrhosis Cholestasis Hepatotoxic drugs Obstructive jaundice
What are the adult/elderly ri for LDH?
100-190 units/l
What are the indications for LDH testing?
Heart Liver RBCs Kidneys Skeletal muscle Brain Lungs
What is the clinical significance of LDH?
Diseased or injured cells lyse release LDH into bloodstream
5 isoenzymes make up total LDH
Where are the 5 LDH enzymes produced?
LDH1 – heart
LDH2 – reticuloendothelial system (makes up the greatest part of LDH)
LDH3 – lungs
LDH4 – kidney, placenta,pancreas
LDH5 – liver, striated muscle
What happens to the LDH levels after an MI?
Rises within 24-48 hours post MI
Peaks in 2-3 days post MI
Returns to normal in 5-10 days
What conditions are asst with increased LDH
MI
Pulmonary disease: embolism, infarction, pneumonia, CHF
Hepatic disease
RBC disease: hemolytic or megaloblastic anemia
Muscular dystrophy
Renal parenchymal disease
Neoplastic states
What are the normal adult, elderly, and children ri for bilirubin?
Total: 0.3 – 1.0 mg/dl
Indirect: 0.2 - 0.8 mg/dl
Direct: 0.1 – 0.3 mg/dl
What are the newborn normal ri for bilirubin?
1.0 – 12.0 mg/dl
What are the critical values for bilirubin?
Adult
>12 mg/dl
Newborn
>15 mg/dl
What are the indications for bilirubin testing?
Evaluate liver function
Hemolytic anemias
Newborn jaundice
What is the clinical significance of bilirubin?
- As RBC’s are broken down in spleen, hemoglobin is released
Hgb heme & globin - Heme broken down to form biliverdin
- Biliverdin is transformed into indirect bilirubin
- Indirect bili is conjugated with glucuronide, Results in conjugated (direct) bili.
- Direct bili is then excreted from liver cells into intrahepatic canaliculi, then hepatic ducts, then CBD, then bowel
What % of total bili is indirect/unconjugated bili?
70-85%
What % of total bili is direct/conjugated bili?
15-30%
At what Tbili level does jaundice occur?
TBili > 2.5 mg/dl
What does jaundice result from?
Normal metabolism of bilirubin
Excretion of bilirubin
Define physiologic jaundice of newborn
Occurs when infant’s liver does not have sufficient conjugating enzymes
Results in high levels unconj (indirect) bili
What complications can occur from jaundice of newborn?
Can pass through blood-brain barrier and cause encephalopathy (kernicterus)
What newborn bili levels indicate treatment?
Bili > 15 in newborns requires immediate treatment – exchange transfusions, light therapy
Increased direct bilirubin implies what type of defect?
- If defect occurs after conjugation bili, direct bili is increased:
A. Consider extrahepatic dysfunction
-Obstruction of CBD by gallstone
-Tumor blocking CBD
Increased indirect bilirubin implies what type of defect?
- If defect occurs before conjugation bil, increased indirect bili:
A. Hepatocellular dysfunction
- Hepatitis
- Cirrhosis
B. Hemolysis
C. Drugs
D. Gilbert Syndrome
What is Gilbert syndrome?
congenital enzyme defect interrupts conjugation of bili; indirect bili rises