26. TYPICAL FORMS OF PATHOLOGY OF THE LIVER. JAUNDICE

Metabolic processes in which the liver plays a major role are the following:

•  intermediate metabolism of amino acids and carbohydrates;

•  synthesis and degradation of proteins and glycoproteins;

•  metabolism and degradation of drugs and hormones;

•  regulation of lipid and cholesterol metabolism.

Etiology of the liver damage:

•  Damage to the liver parenchyma or bile ducts:

 —   hepatitis (viral, bacterial, toxic);

 —   dystrophy;

 —   cirrhosis;

 —   tumors;

 —   parasites;

 —   gall bladder stones, inflammation of the bile ducts with cholestasis.

•  Extrahepatic causes:

 —   shock;

 —   heart failure;

 —   general hypoxia;

 —   renal failure;

 —   protein malnutrition;

 —   metastases in the liver.

LIVER FAILURE

Liver failure is characterized by a decrease of one or many functions below the level required to maintain normal homeostasis. It can be classified by the number of deranged functions as partial and total; by the clinical course as acute and chronic; and by the outcome as lethal and nonlethal. The common mechanisms operating in liver failure are described in fig. 35.

Fig. 35

Manifestations of liver failure:

•  Carbohydrate metabolism:

 —   hyperglycemia, glucose intolerance;

 —   increased blood lactate levels;

 —   hypoglycemia.

•  Amino acid and ammonia metabolism:

 —   elevated levels of aromatic amino acids and methionine;

 —   normal or depressed levels of the branched-chain amino acids;

 —   increased levels of free amino acids;

 —   a reduction in blood urea nitrogen;

 —   an accumulation of ammonia in the blood.

•  Protein synthesis and degradation:

 —   hypoprothrombinemia;

 —   hypoalbuminemia;

 —   a decreased plasma concentration of factor V;

 —   an increased production of fibrinogen (possibly abnormal) and other acute-phase reactants (C-reactive proteins, haptoglobin, etc.);

 —   decreased blood activity of choline esterase.

•  Detoxification:

 —   a decreased detoxification of noxious products of amino acid metabolism absorbed in the gastointestinal tract (phenol, indol, cadaverin, tyramine, etc.);

 —   a decreased detoxification of hormones:

    ◊  insuline, glucagon;

    ◊  thyroxine and triiodothyronine;

    ◊  estrogens, such as estradiol;

    ◊  epinephrine;

 —   a decreased detoxification of drugs.

•  Lipid metabolism:

 —   an accumulation of lipids in the liver;

 —   a decrease in total serum cholesterol (free and esterified) levels;

 —   an increase in total the serum cholesterol.

•  Pigment metabolism:

 —   an accumulation of unconjugated bilirubin;

 —   an accumulation of conjugated bilirubin.