Protein metabolism
(Key words: protein, albumin, serum protein electrophoresis, coagulation factor, rapid turnover protein, PIVKA, APTT, PT, DIC, Vitamin K dependent factor)
1) Albumin
- Hepatocyte: the only site of albumin synthesis
- Post and Patek (1942) relation of serum albumin to prognosis of cirrhosis
- Salting-out method:include globulins
- Degradation
- Distribution---cirrhotic patient: plasma volume increase by 25%, the actual amount of albumin not as little as measured
- Loss---A/G ratio: not suitable expression ---renal disease, protein loosing gastro-enteropathy
- Half life: 19 ~ 21 days
2) Serum protein electrophoresis (R-E system--gamma-globulin)
- Five fractions--A, alpha-1-globulin, alpha-2-globulin, beta--globulin, gamma-globulin
- Total protein amount
- Except for gamma-globulin, other four proteins are only synthexsized by liver cells
- gamma-globulin: synthesized by B-lynphocyte
- Every protein is simple protein: less sensitive
- alpha-1-G is more sensitive than alpha-2-G and beta-G in reflection of liver cell damage
- alpha-1-AT(antitrypsin): positive acute reactanct protein
acute hepatitis: ¡ô
massive hepatic necrosis: ¡õ
3) Rapid turnover protein
- Albumin half life ------ 19 ~ 21 days
- Do not reflect defect of capacity of protein synthesis in early stage liver cell damage
- Some globulins -----half life of several hours to days
- -- Prealbumin, alpha-1-acid glycoprotein, hemopexin, transferin
- -- Positive acute phase reactant protein----
£\1-antitryposin, alpha-2-HS-glycoprotein, ceruloplasmin
- Most of alpha-1-glycoprotein: alpha-1-AT
- Polyacrylamide gradient gel electrophoresis, Single Radial Immuno Difusion
- pre-A, alpha-1-AG and alpha-1-AT, Ceruloplasmin
4) Coagulation factors
- I, II, III, IV, VII, IX, X, XII, XIII
- Except for VIII, liver is the only site for synthesis
- Reflect the damage of liver cell
- PT (Prothrombin Time):---I, II, V, VII, X (Extrincic pathway)
- APTT (Activated Partial Throboplastin Time): --- I, II, V, IX, XI, XII (intrincic pathway)
- Normotest (Owren): --- II, X, VII
- Fibrinogen
- Factor V
- Factor VII
Coagulation system
Extrincic pathway: Tissue factor ---¡÷VII
Intricic pathway: XII ¡÷XI¡÷IX¡÷VIII
VII + VIII ¡÷ X ¡÷ Xa
Xa + V ¡÷ II ¡÷ Thrombin
Thrombin ¡÷ I ¡÷ Fibrin
Thrombin ¡÷ XIII ¡÷ prevent fibrinolysis
PT (Prothrombin Time)
- If APTT is normal --- VII deficiency
- Factor VII --- shortest half life (6 hours)
APTT (Activated Partial Thromboplastin Time)
If PT is normal --- IX, XI, XII deficiency
Normotest (Owren's, Hepatoplastin test)
- Not influenced by PIVKA (prtein induced by vitamin K absence)
- Thrombotest: influenced by PIVKA, test for vitamin K deficiency
Vitamin K-dependent factors
- II, VII, IX, X
- influence both PT and APTT
DIC (Disseminated Intravascular Coagulation)
