1. Lab (2): Liver Function profile (LFT)
Khadija Balubaid
KAU-Faculty of Science- Biochemistry department
Clinical biochemistry lab (Bioc 416)
2012

2. Profile : is group of tests specific for one organ

3. Liver Liver is an important organ in human body
Synthesis of proteins, glycogen storage, drug metabolism and detoxification process
Many diseases can affect liver functions as:
Viruses (heptites A,B,C,D,G)
Cirrhosis
Inflammation
Jaundice
Fatty liver
Albumin, clotting factos

4. Liver diseases

6. Liver Function Test (LFT) profile
Integrity of liver cells
Execratory function
Synthetic function
Clinical Lab tests
Proteins
TP, Alb, A/G ratio
Liver enzymes
AST, ALT, GGT, ALP
Bilirubin, ALP

7. SGPT (Serum Glutamate Pyruvate Transaminase)
Liver enzymes
ALT (alanine amino transferase) or i v e r
SGPT (Serum Glutamate Pyruvate Transaminase)
Produced by liver cells.
High serum ALT due to:
Liver cells damage due to inflammation, virus infection or cell death (why?) when liver cells damaged ALT enzyme leaks to blood stream leads to rise its level in serum.
Some medication may also elevate serum ALT, because some drugs cause liver damage leads to rise ALT level.
ALT is the most sensitive marker for liver cell damage; since it is only synthesized by liver cells other enzymes may be also synthesized by other organs.
or SGPT

8. AST (Aspartate amino transferase) or
SGOT (Serum Glutamate Oxaloacetate Transaminase)
Synthesized by : liver, cardiac muscle and skeletal muscles
Less sensitive that ALT
High serum AST due to:
Muscle damage, myocardial infarction (heart attack) and in chronic liver disease. To confirm that high AST is due to heart or muscle injury; other enzyme (creatinine kinase CK) which is specific for heart, is also tested.
Because it is less sensitive the ration ALT/AST is calculated

9. ALP (alkaline phosphatase)
It is related to bile duct.
It is not specific for bile because it is synthesized also by bone and placenta (isoenzymes)
High serum ALP may be due to:
bile duct damage (inflammation, cirrhosis or obstruction)
In alcohol hepatitis.
Normal physiological elevation :
During pregnancy
During child growth
To assess the etiology of ALP elevation, GGT and bilirubin levels are also measured.

10. GGT (Gamma Glutamic Transpeptidase)
Produced by liver, kidney and pancreas
Elevated in: toxins, alcohol
To confirm hepatic etiology of ALP elevation

11. Conformational procedures
General indications
In general, every enzyme can gives you specific indication:
Conformational procedures
Indications
Enzymes
Serology (for virus)
Biopsy,
ultrasound (liver size)
Hepatitis.
may be due to ( virus, medication, toxin)
ALT
AST/ALT ratio,
CK to confirm heart disease
Not specific.
May be due to ( muscle disease, heart disease, liver disease)
AST
GGT to confirm liver
Gallbladder ultrasound
Bile problems (stone or bilary duct obstruction)
Liver disease
Normal physiological elevation ( child, pregnancy)
ALP
Liver toxin, alcohol, cirohsis
GGT

12. Experiment: Measuring serum AST level
Principle:
The rate of NADH oxidation is directly related to AST activity which measured photometrically.
L-aspartate + a oxoglutarate L-glutamate + oxaloacetate
Oxaloacetate + NADH + H L-malate + NAD +
AST
MDH

13. Notes:
Samples:
Unhemolyzed serum or plasma collected in heparin or EDTA tube.
Stability of AST in serum:
2 days at 20-25oC or 4 days at 2-8oC

14. Kit components Reagent 1:
mixture of: buffer (pH 7.5) + substrate (L-aspartate)
Reagent 2:
mixture of: enzyme (MDH) + coenzyme (NADH)

15. Procedure Prepare working reagent: by mixing reagent 1 and 2 together
Zero adjust the spectrophotometer with air or dis. H2O
Prepare the reaction as the following:
Mix
After 30 sec. read the absorbance at 340nm. (R1)
Repeat the reading after 1min and 2 min (R2, R3)
Calculate the mean absorbance
mean = R1+R2+R3/ or (R2-R1)+(R3-R2)/2
Sample tube
1 ml
Working reagent
100 ml
Sample (serum)

16. AST catalytic conc. U/L = mean A X factor
Calculations:
AST catalytic conc. U/L = mean A X factor
* factor = 1946
Reference value “ normal rang”:
25oC
18 U/L
Men
15 U/L
Women

17. Interfering factors Therapeutic heparin increase AST
Hemolysed blood increase AST
Many drugs falsely increase or decrease AST