Chemistry

The hepatocellular leakage enzymes are useful in detecting injury to liver parenchymal cells. Generally, increased serum activity represents enzyme leakage from cells through damaged cell membranes. ALT: Used in small animals only. Largely liver-specific, but can also increase in severe myopathies (release of muscle enzyme) and intravascular or in vitro hemolysis (cat, pig). AST: Used […]

Globulins can be divided into three fractions based on their electrophoretic mobility. Most of the α and β globulins are synthesized by the liver, whereas γ globulins are produced by lymphocytes and plasma cells in lymphoid tissue. α globulins consist of α-1 and α-2 globulins, and β globulins consist of β-1 and β-2 globulins. A

Albumin is a globular protein with a molecular weight of 66-69,000 daltons (66-69 kDa). It is synthesized in the liver and is catabolized in various tissues where it is taken up by pinocytosis. Uptake and degradation is facilitated if the protein is structurally modified.  The constituent amino acids are utilized by the cells. Physiology Albumin makes

Total protein is the sum concentration of all individual serum proteins (g/dL). There are many hundreds of different protein species in serum, including straight polypeptides as well as glycosylated and lipid-associated forms. Measurement of total protein for clinical purposes commonly is performed by the following methods. Methods used to measure total protein Refractometry This method

Total body phosphate is found mostly in bone (80-85%), with smaller amounts in muscle and the extracellular fluid (<1%). Phosphate is the major intracellular anion. Terms associated with phosphate are confusing: Phosphorus: The chemical element. Since it is unstable, phosphorous is never found free, but is always in the oxidized state (PO43-). Phosphate: Phosphorus bound

Magnesium is a major intracellular cation, second only to potassium in abundance. In cells, magnesium is involved as a catalyst or activator in many enzymatic reactions; it is needed for all reactions that utilize ATP, since a Mg-ATP complex is the immediate substrate in these reactions. The majority of the body’s magnesium is present in bone (50%) and skeletal

Total serum calcium comprises three major forms: Free ionized calcium (about 50-55% of total) Protein bound (about 35-45% of total). Most of the protein-bound calcium is bound to albumin (80%, with the rest bound to globulins), likely to imidazole groups. Complexed with anions such as bicarbonate, citrate, lactate, and phosphate (about 5-10% of total). Ionized

Physiology Creatinine is produced as the result of normal muscle metabolism. Phosphocreatine, an energy-storing molecule in muscle, undergoes spontaneous cyclization to form creatine and inorganic phosphorous. Creatine then decomposes to creatinine. Note that creatine is actually produced in the liver from amino acids (glycine and arginine). In health, production and excretion of creatinine are fairly

Physiology Urea is synthesized by hepatocytes from ammonia generated by catabolism of amino acids derived either from digestion of proteins in the intestines or from endogenous tissue proteins. Urea is excreted by the kidneys, colon (high in horses), saliva and sweat. In ruminants, urea is excreted into the gastrointestinal system (mostly saliva) where it is

The body strives to maintain electroneutrality at all times by keeping the concentrations of anions equivalent to cations in serum (or plasma). In a healthy individual, sodium and potassium (also called “measured” cations) account for about 95% of total cations, whereas chloride and bicarbonate (also called “measured” anions) account for about 85% of the total