Glucose metabolism begins with glycolysis, in which the molecule is broken down into<unk>  in ten enzymatic steps. A significant proportion of<unk>  is converted into lactate (usually 10:1). The human metabolism produces about 20 mmol/kg of lactic acid every 24 hours. This happens predominantly in tissues (especially muscle) that have high levels of the "A" isoform of the enzyme lactate dehydrogenase (LDHA), which predominantly converts<unk>  into lactate. The lactate is carried by the bloodstream to other tissues where it is converted at the expense of ATP back to<unk>  by the "B" isoform of LDH (LDHB). Firstly there is gluconeogenesis in the liver (as well as the kidney and some other tissues), where<unk>  is converted into glucose; this is known as the Cori cycle. In addition, lactate moved to other tissues enters the citric acid cycle and eventually oxidative phosphorylation, a process that yields ATP. Elevations in lactate are either a consequence of increased production or of decreased metabolism. With regards to metabolism, this predominantly takes place in the liver (70%), which explains that lactate levels may be elevated in the setting of liver disease. In "type A" lactic acidosis, the production of lactate is attributable to insufficient oxygen for aerobic metabolism. If there is no oxygen available for the parts of the glucose metabolism that require oxygen (citric acid cycle and oxidative phosphorylation), excess<unk>  will be converted in excess lactate. In "type B" lactic acidosis the lactate accumulates because there is a mismatch between glycolysis activity and the remainder of glucose metabolism. Examples are situations where the sympathetic nervous system is highly active (e.g. severe asthma). There is controversy as to whether elevated lactate in acute illness can be attributed to tissue hypoxia; there is limited empirical support for this theoretical notion.
symptom of Pyruvate carboxylase deficiency
symptom of Glucose-6-phosphate dehydrogenase deficiency
symptom of Adenylosuccinate lyase deficiency
symptom of Phenylketonuria
symptom of Glycogen storage disease type III
symptom of Dubin–Johnson syndrome
symptom of Beta-mannosidosis
complications of Pyruvate carboxylase deficiency