Lactic Acidosis
A buildup of lactic acid that makes the blood too acidic
Quick Facts
- Type: Metabolic emergency
- Cause: Excess lactic acid production or reduced clearance
- Common trigger: Low oxygen to tissues (e.g. shock, sepsis)
- Urgency: Often a medical emergency
Overview
Lactic acidosis is a type of metabolic acidosis, a condition in which the blood becomes too acidic. It happens when lactic acid (lactate) builds up faster than the body can remove it. Lactate is produced normally when cells make energy without enough oxygen, but in lactic acidosis the amount becomes excessive.
Lactic acidosis is usually a sign of a serious underlying problem rather than a disease on its own. It most often occurs when tissues are starved of oxygen, such as in shock or severe infection, or when the liver or kidneys cannot clear lactate. Because the underlying causes are frequently life-threatening, lactic acidosis is generally treated as a medical emergency, with care directed at the cause.
Symptoms
Symptoms are often those of the underlying illness combined with the effects of acidosis. They may include:
- Rapid or deep breathing as the body tries to compensate
- Nausea and vomiting
- Abdominal pain
- Weakness and fatigue
- Confusion or drowsiness
- A fast heartbeat and low blood pressure
Lactic acidosis can be a medical emergency. Severe weakness, fast breathing, confusion, or signs of serious illness, especially with an infection, heart problem, or certain medications, need urgent evaluation.
Causes
Lactic acidosis is often grouped by mechanism:
- Reduced oxygen to tissues (type A): Shock, severe infection (sepsis), heart failure, very low blood pressure, severe anemia, or extreme exertion.
- Other causes without obvious oxygen lack (type B): Liver or kidney disease, certain cancers, some medications and toxins, and rare inherited metabolic disorders.
- Medications: Notably the diabetes medicine metformin, which rarely causes lactic acidosis, usually when kidney function is poor or another illness is present.
- Alcohol and certain poisons in some cases.
Risk Factors
- Serious infection or sepsis
- Shock, heart failure, or low blood pressure
- Kidney or liver disease
- Use of metformin, particularly with reduced kidney function or acute illness
- Severe dehydration or major surgery
- Certain cancers and rare metabolic disorders
Diagnosis
Lactic acidosis is diagnosed with blood tests and an assessment of the underlying cause:
- Blood lactate level, which is elevated.
- Blood gas analysis to confirm the blood is too acidic and assess severity.
- Tests for the cause, such as markers of infection, kidney and liver function, blood counts, and heart tests.
- Imaging as needed to find a source of infection or other problem.
Because lactic acidosis points to a serious condition, evaluation is usually urgent and thorough.
Treatment
Treatment centers on correcting the underlying cause and supporting the body, usually in a hospital and often in intensive care:
- Treating the cause: For example, antibiotics and fluids for sepsis, restoring blood flow and oxygen in shock, or treating heart or kidney problems.
- Restoring oxygen delivery: Oxygen, intravenous fluids, and support for blood pressure as needed.
- Stopping or adjusting medications that may be contributing, such as metformin.
- Dialysis in some severe cases, particularly when caused by certain drugs or kidney failure.
- Close monitoring of lactate, blood acidity, and vital signs.
The outlook depends heavily on the underlying cause and how quickly it is treated.
Prevention
- Manage chronic conditions such as heart, kidney, and liver disease
- Stay hydrated, especially during illness
- Use metformin as directed and follow guidance to pause it during serious illness, dehydration, or before certain procedures
- Seek prompt care for serious infections and signs of shock
- Attend recommended monitoring if you take medications that can affect lactate
When to See a Doctor
Seek emergency care if you have:
- Rapid or deep breathing with weakness or confusion
- Severe illness, especially with a known infection, heart, kidney, or liver problem
- Persistent vomiting, abdominal pain, and feeling very unwell while taking metformin
- Signs of shock, such as a racing heart, low blood pressure, or cold, clammy skin
Lactic acidosis usually signals a serious underlying problem and needs prompt medical attention.
Frequently Asked Questions
What is lactic acidosis?
Lactic acidosis is a buildup of lactic acid in the body that makes the blood too acidic. It usually happens when tissues do not get enough oxygen or when the liver and kidneys cannot clear the acid, and it is typically a sign of a serious underlying illness.
Is lactic acidosis an emergency?
It often is, because the conditions that cause it, such as sepsis, shock, or heart failure, are themselves life-threatening. Symptoms like fast or deep breathing, confusion, and severe weakness need urgent medical evaluation.
Can metformin cause lactic acidosis?
Rarely, yes. The diabetes medicine metformin can contribute to lactic acidosis, usually when kidney function is reduced or another serious illness is present. This is why metformin is often paused during severe illness, dehydration, or certain procedures.
What are the symptoms of lactic acidosis?
Symptoms can include rapid or deep breathing, nausea, vomiting, abdominal pain, weakness, fatigue, and confusion, often alongside signs of the underlying illness. These can develop quickly and warrant prompt assessment.
How is lactic acidosis treated?
Treatment focuses on the underlying cause, such as antibiotics and fluids for infection or restoring blood flow in shock, along with oxygen, fluids, and support for blood pressure. Some severe cases need dialysis, and contributing medications may be stopped.
References
- MedlinePlus, U.S. National Library of Medicine. Lactic acidosis.
- Merck Manual. Lactic acidosis.
- StatPearls, National Library of Medicine. Lactic acidosis.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).