Lactic acidosis is a potentially life-threatening condition that can be fatal without proper treatment. Severe forms of lactic acidosis are more likely to occur in patients in critical conditions. To understand the concept of lactic acidosis, it is necessary to know some information about glucose metabolism in the body.
Glucose is a sugar, which is the essential source of energy. In normal conditions, the glucose is converted into energy-rich compounds (called ATP) by a series of metabolic reactions. The glucose metabolism is quite efficient in energy production but it needs oxygen. If there is an oxygen deficiency in the tissue, the cells have to generate ATP molecules by alternative metabolic pathways. Such is the conversion of glucose to lactate (lactic acid). It does not need oxygen but it produces only small amount of energy and leads to excessive production of hydrogen ions, thus resulting in acidification of the organism.
Lactic acidosis is therefore characterized by an increase in the concentration of lactate (lactic acid) in blood, associated with a decrease in pH (i.e. increased acidity).
Most cases of the lactic acidosis are caused by insufficient oxygenation of tissues, which is present in many serious conditions associated with circulatory failure such as sepsis, shock states and other cases of severe physical stress. Lactic acidosis is also a dangerous complication of certain medications, typically the oral antidiabetic drugs containing a substance known as metformin*.
* Metformin is a basic substance used for the treatment of type 2 diabetes. It enhances tissue sensitivity to insulin and decreases liver output of glucose. However, if metformin is administered to a patient with acute or chronic renal failure, it accumulates in the body. By disrupting the glucose production in liver, metformin decreases uptake of lactic acid by liver tissue, accumulation of lactate and lactic acidosis.
The condition manifests with overall discomfort, lethargy, nausea and vomiting. The quality of consciousness deteriorates and the disruption of internal environment may progress to coma and death. A typical sign is accelerated and deep breathing (so-called Kussmaul breathing) when the organism tries to breath out carbon dioxide in response to the acidification.
Blood tests show us low pH and increased lactate concentration. In addition, we can found signs of the condition, which is the causative factor of lactic acidosis.
It is necessary to treat the underlying cause and support the cardio-respiratory system. Accumulated lactate and metformin can be removed by acute dialysis. If the acidity is severe and threatens the life, it is possible to administer alkaline compounds such as sodium bicarbonate to normalize the pH in the body.