Liver Function Tests (LFT’s)
General Information
Specific Liver Function Tests (LFT’s)
Aminotransferases (see Serum Aminotransferases , [[Serum Aminotransferases]])
Alkaline Phosphatase (see Serum Alkaline Phosphatase , [[Serum Alkaline Phosphatase]])
Origin of Alkaline Phosphatase
Bone
Intestine
Kidney
Liver
Third Trimester Placenta
Determination of Origin
Elevated Alkaline Phosphatase Associated with a Normal Gamma-Glutamyl Transpeptidase or 5′-Nucleotidase Suggests a Non-Hepatic Source of the Alkaline Phosphatase
Fractionation of Alkaline Phosphatase : may also be used to determine origin
Heat-Labile Alkaline Phosphatase: suggests bone origin (“bone burns”)
Heat-Stable Alkaline Phosphatase: suggests liver origin
Alkaline Phosphatase Levels are Age-Dependent
Alkaline Phosphatase Levels are Higher (Up to 3x Adult Levels) in Children and Adolescents : due to physiologic osteoblastic activity
Normal Alkaline Phosphatase Level Increases from 40 to 65 y/o : especially in women
Bilirubin (see Serum Bilirubin , [[Serum Bilirubin]])
Gamma-Glutamyl Transpeptidase (GGT) (see Serum Gamma-Glutamyl Transpeptidase , [[Serum Gamma-Glutamyl Transpeptidase]])
General Comments
Gamma-Glutamyl Transpeptidase is Elevated in Normal Neonates : levels decrease and reach adult levels by 5-7 mo of age
Origin of Gamma-Glutamyl Transpeptidase
Biliary Epithelial Cells
Brain
Heart
Hepatocytes
Kidney
Pancreas
Seminal Vesicle
Spleen
5′-Nucleotidase (see Serum 5′-Nucleotidase , [[Serum 5′-Nucleotidase]])
General Comments
Physiologic Function of 5′-Nucleotidase is Unknown
Origin of 5′-Nucleotidase
Blood Vessels
Brain
Endocrine Pancreas
Heart
Liver : liver is the only organ which releases 5′-nucleotidase into the serum
Lactate Dehydrogenase (LDH) (see Serum Lactate Dehydrogenase , [[Serum Lactate Dehydrogenase]])
General Comments
LDH is a Cytoplasmic Enzyme Found in Many Organs
There are 5 LDH Isoenzymes of LDH Present in the Serum : isoenzymes can be separated by electrophoresis
Slowest Migrating Isoenzyme is the Predominant Form Present in the Liver
Origin of Lactate Dehydrogenase Isoenzymes
LDH-1 (4H) Isoenzyme
Brain
Heart
Red Blood Cell (RBC)
LDH-2 (3H1M) Isoenzyme
Reticuloendothelial System
LDH-3 (2H2M) Isoenzyme
LDH-4 (1H3M) Isoenzyme
LDH-5 (4M) Isoenzyme
References
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