What are the types of lactic acidosis?

From the Guidelines

Lactic acidosis can be classified into two main types: Type A and Type B.

Types of Lactic Acidosis

• Type A lactic acidosis is caused by tissue hypoxia, which can occur in conditions such as shock, sepsis, or cardiac arrest, as seen in patients with traumatic haemorrhagic shock 1. This type is often associated with poor perfusion and oxygen delivery to tissues.
• Type B lactic acidosis is further divided into three subtypes:
  • Type B1, which is caused by underlying diseases such as diabetes, liver or kidney disease, or cancer.
  • Type B2, which is associated with certain medications, including metformin, nucleoside reverse transcriptase inhibitors, and propofol, as reported in studies 1.
  • Type B3, which is caused by inborn errors of metabolism, such as mitochondrial disorders or congenital lactate metabolism defects.

Medications like metformin can increase the risk of lactic acidosis, especially when taken in high doses or in patients with renal impairment 1. The typical dose of metformin is 500-1000 mg twice daily, but it should be used with caution in patients with kidney disease.

Management of Lactic Acidosis

Early recognition and treatment of the underlying cause are crucial in managing lactic acidosis, as emphasized in the European guideline on management of major bleeding and coagulopathy following trauma 1. Treatment may involve supportive care, such as fluid resuscitation and oxygen therapy, as well as specific interventions to address the underlying condition.

From the Research

Types of Lactic Acidosis

• Type A: caused by tissue hypoxia and/or hypoperfusion 2, 3, 4, 5
• Type B: caused by deranged metabolic activity in the cells in the absence of hypoxia/hypoperfusion 2, 3, 4, 5

Characteristics of Type A and Type B Lactic Acidosis

• Type A:
  • More common 3, 5
  • Caused by lack of oxygen (tissue hypoxia or hypoperfusion) 4
  • Impaired cellular respiration leads to lower pH level and increased production of lactate 4
• Type B:
  • Relatively rare 4
  • Occasionally found in patients with hematological malignancies, such as leukemia or lymphoma 4
  • Molecular mechanism not fully understood 4
  • May be caused by drug side-effects, toxins, enzymatic defects, inherited or acquired 5

Coexistence of Type A and Type B Lactic Acidosis

• A challenging case of coexisting Type A and Type B lactic acidosis has been reported 6
• The patient had newly diagnosed poorly differentiated neuroendocrine metastatic carcinoma and renal cell carcinoma 6
• The patient's persistently elevated lactic acidosis may have resulted from the inherent malignancy 6