Types of lactic acidosis
Pro Research Analysisby 
Searched over 200M research papers
Consensus Meter
Types of Lactic Acidosis: An Overview
Lactic acidosis is a metabolic condition characterized by an accumulation of lactate in the body, leading to a decrease in blood pH. It is broadly classified into two main types: Type A and Type B lactic acidosis. Understanding these types is crucial for effective diagnosis and treatment.
Type A Lactic Acidosis: Hypoxic Causes
Tissue Hypoxia and Circulatory Insufficiency
Type A lactic acidosis is primarily caused by tissue hypoxia, where the body's tissues are deprived of adequate oxygen. This condition often arises from circulatory insufficiency, such as in cases of shock, sepsis, or cardiopulmonary arrest . The lack of oxygen forces cells to switch to anaerobic metabolism, leading to the overproduction of lactate. Common clinical scenarios include pulmonary edema, multi-organ failure, and severe infections .
Clinical Presentation and Mortality
Patients with Type A lactic acidosis typically present with symptoms related to the underlying cause of hypoxia, such as dyspnea, tachypnea, and altered mental status. The condition is associated with high mortality rates, especially when blood lactate levels exceed 9 mmol/L.
Type B Lactic Acidosis: Non-Hypoxic Causes
Drug Side-Effects and Toxins
Type B lactic acidosis occurs in the absence of tissue hypoxia and is often related to drug side-effects, toxins, or metabolic disorders. Notably, the antidiabetic drug phenformin has been linked to a significant number of Type B lactic acidosis cases, although its use has declined due to its high mortality rate . Other drugs, such as metformin, also pose a risk, particularly in patients with renal or cardiac dysfunction.
Metabolic and Enzymatic Defects
This type of lactic acidosis can also result from inherited or acquired enzymatic defects that affect lactate metabolism. Conditions such as glycogen storage diseases, thiamine deficiency, and certain myopathies fall into this category . For instance, thiamine deficiency, often seen in malignancies, can lead to impaired lactate utilization and subsequent acidosis.
Malignancies and Hematological Disorders
Type B lactic acidosis is sometimes observed in patients with malignancies, including both solid tumors and hematological cancers like leukemia and lymphoma . The exact mechanism is not fully understood, but it is believed that cancer cells may produce excess lactate due to aberrant metabolic pathways .
Mixed Type A and Type B Lactic Acidosis
Complex Clinical Scenarios
In some cases, patients may present with a combination of both Type A and Type B lactic acidosis. This can occur in critically ill patients with conditions such as sepsis and malignancy, where both hypoxic and non-hypoxic factors contribute to elevated lactate levels . Differentiating between the two types is essential for appropriate treatment, as the management strategies differ significantly.
Conclusion
Lactic acidosis is a complex condition with diverse etiologies. Type A lactic acidosis is primarily due to tissue hypoxia and circulatory insufficiency, while Type B is associated with non-hypoxic causes such as drug side-effects, metabolic defects, and malignancies. Understanding the underlying mechanisms and clinical presentations of each type is crucial for effective diagnosis and treatment. Prompt recognition and targeted therapy remain the cornerstone of managing lactic acidosis.
Sources and full results
Most relevant research papers on this topic