Lactic acid was first found & described in sour milk by Karl Wilhelm Scheele in 1780. German physician–chemist Johann Joseph Scherer (1841–1869) demonstrated the occurrence of lactic acid in human blood under pathological conditions in 1843 & 1851.
Lactic acid is essentially a carbohydrate within cellular metabolism and its levels rise with increased metabolism during exercise and with catecholamine stimulation. Glucose-6-phosphate is converted anaerobically to pyruvate via the Embden-Meyerhof pathway. Pyruvate is in equilibrium with lactate with a ratio of about 25 lactate to 1 pyruvate molecules. Thus, lactate is the normal endpoint of the anaerobic breakdown of glucose in the tissues.
The causes of lactic acidosis can generally be divided into
those associated with obviously impaired tissue oxygenation (type A) and those
in which systemic impairment in oxygenation does not exist or is not readily apparent
(type B). However, there is frequently overlap between type A and type B lactic
acidosis. In sepsis, for example, there is both an increase in lactate
production resulting from microcirculatory failure and also a decrease in
lactate clearance that is not solely due to diminished oxygen delivery.
Satyendra Dhar MD,
