Tiêu đề 12. LIVER FUNCTION.pdf ✅

PHARMD GURU Page 1 LIVER FUNCTION A. Liver enzymes 1. Levels of certain enzymes (e.g., LDH, ALP, AST, and ALT) increase with liver dysfunction. 2. These enzyme tests indicate only that the liver has been damaged. They do not assess the liver’s ability to function. Other tests provide indications of liver dysfunction. B. Serum bilirubin: 1. Bilirubin, a breakdown product of Hb, is the predominant pigment in bile. Effective bilirubin conjugation and excretion depend on hepatobiliary function and on the rate of RBC turnover. 2. Serum bilirubin levels are reported as total bilirubin (conjugated and unconjugated) and as direct bilirubin (conjugated only). a. Bilirubin is released by Hb breakdown and is bound to albumin as water- insoluble indirect bilirubin (unconjugated bilirubin), which is not filtered by the glomerulus. b. Unconjugated bilirubin travels to the liver, where it is separated from albumin, conjugate with diglucuronide, and then actively secreted into the bile as conjugated bilirubin (direct bilirubin), which is filtered by the glomerulus. 3. Normal values of total serum bilirubin are 0.1 to 1.0 mg/dL (2 to 18 mmol/L); of direct bilirubin: 0.0 to 0.2 mg/dL (0 to 4 mmol/L). CLINICAL LABORATORY TESTS USED IN THE EVALUATION OF DISEASE STATES, AND INTERPRETATION OF TEST RESULTS
PHARMD GURU Page 2 BILIRUBIN METABOLISM:- 4. An increase in serum bilirubin results in jaundice from bilirubin deposition in the tissues. There are three major causes of increased serum bilirubin: a. Hemolysis increases total bilirubin; direct bilirubin (conjugated) is usually normal or slightly increased. Urine colour is normal, and no bilirubin is found in the urine. b. Biliary obstruction, which may be intrahepatic (as with a chlorpromazine reaction) or extra hepatic (as with a biliary stone), increases total bilirubin and direct bilirubin; intrahepatic cholestasis (e.g., from chlorpromazine) may increase direct bilirubin as well. Urine colour is dark, and bilirubin is present in the urine. c. Liver cell necrosis, as occurs in viral hepatitis, may cause an increase in both direct bilirubin (because inflammation causes some bile sinusoid blockage) and indirect bilirubin (because the liver’s ability to conjugate is altered). Urine color is dark, and bilirubin is present in the urine.
PHARMD GURU Page 3 C. Serum proteins: 1. Primary serum proteins measured are albumin and the globulins (i.e.α, β, γ ) Albumin (4 to 6 g/dL) maintains serum oncotic pressure and serves as a transport agent. Because it is primarily manufactured by the liver, liver disease can decrease albumin levels. Albumin can also be used to assess nutritional status. Globulin (23 to 35 g/L) relates to the total measurement of immunoglobins (antibodies) found in the serum and function as transport agents and play a role in certain immunological mechanisms. A decrease in albumin levels usually results in a compensatory increase in globulin production. 2. Normal values for total serum protein levels are 6 to 8 g/dL (60 to 80 g/L).