Lactic Acidosis: What You Need to Know
Medically reviewed by Michael Menna, DO
Lactic acidosis is a health condition characterized by elevated lactate levels in the body. These high lactate levels may result from increased cell production, decreased clearance (mainly within the liver), or some combination.
Lactate is a natural fuel source for cells and is a product of anaerobic metabolism, a process whereby cells break down glucose (sugar) for energy in the presence of low oxygen levels.
Depending on the type and cause, lactic acidosis can be mild (e.g., when caused by overexercising) or severe, requiring prompt and aggressive hospital care (e.g., when caused by a serious infection).
This article explores lactic acidosis, including types, causes, symptoms, diagnosis, and treatment. It will also briefly review what a high lactate level means regarding potential medical outcomes.
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Types of Lactic Acidosis
Lactic acidosis is a form of metabolic acidosis, a condition of excess acid in the bloodstream.
The two main types are:
Type A lactic acidosis is characterized by overproduction of lactic acid due to a significant lack of oxygen reaching vital organs—what's known as systemic or widespread hypoperfusion.
Type B lactic acidosis is characterized by disturbances in cell metabolism, which is how cells utilize oxygen to create energy. Unlike type A, type B lactic acidosis is not associated with inadequate tissue oxygenation and hypoperfusion.
What Causes Lactic Acidosis?
There are many causes of lactic acidosis, and sometimes the two types overlap.
Type A Lactic Acidosis
Septic shock is one of the most common causes of type A lactic acidosis. It's a life-threatening condition caused by an infection spreading throughout the body.
The infection that leads to septic shock can stem from within any organ, including the lungs (pneumonia), kidneys (urinary tract infection), or abdomen (e.g., appendicitis).
Related: What Are the Early Signs of Sepsis?
Hypovolemic shock is another frequent cause of type A lactic acidosis. It develops due to a massive loss of blood or other bodily fluids.
Possible causes of hypovolemic shock include:
Internal bleeding (e.g., from a stomach ulcer, car accident, or injured blood vessel)
Extensive burns
Persistent diarrhea and vomiting
Learn More: How Much Blood Is in the Human Body?
Cardiogenic shock, which develops due to the heart malfunctioning, can also cause type A lactic acidosis. With cardiogenic shock, the heart fails to pump blood to vital organs. A heart attack is the most common trigger for cardiogenic shock, accounting for 81% of cases.
Learn More: How Many People Survive a Heart Attack?
Besides shock, other scenarios or conditions that can lead to type A lactic acidosis include:
Strenuous physical exercise stimulates anaerobic metabolism, prompting the body to produce lactate as insufficient oxygen reaches the muscles.
Seizures or severe shivering stimulate anaerobic metabolism and lactate production due to excess muscle shaking and subsequent oxygen utilization.
Type B Lactic Acidosis
Causes of type B lactic acidosis include:
Liver disease can impair the clearance of lactate.
Alcohol use disorder can lead to liver failure, so lactate cannot be cleared. Also, thiamine (vitamin B1) deficiency can develop, which triggers the body to shift to anaerobic metabolism.
Diabetic ketoacidosis (DKA) is a complication of diabetes resulting from inadequate insulin levels, a hormone that helps sugar enter cells. In DKA, metabolic disturbances increase lactate in the bloodstream.
HIV/AIDS can lead to mixed (type A and B) lactic acidosis as a result of increased risk of infection/sepsis and use of antiretroviral medications (see below).
Cancer may cause mixed lactic acidosis due to an increased risk of infection/sepsis from chemotherapy or from the underlying cancer itself—what's known as the Warburg effect, where cancer cells revert to anaerobic metabolism.
Certain medications and toxins can also lead to type B lactic acidosis. A prime example is a diabetes drug called metformin. Metformin works in the liver and gut to lower blood sugar levels, but it can also increase lactic acid levels in the bloodstream by blocking energy production in the liver.
Who Is at Risk for Lactic Acidosis From Metformin?
People most at risk for metformin-induced lactic acidosis are those with underlying kidney disease and other conditions that make them vulnerable to hypoperfusion (e.g., sepsis).
Other drugs and toxins associated with type B lactic acidosis include:
Nucleoside reverse-transcriptase inhibitors (NRTIs) are antiretroviral drugs used to treat HIV.
Aspirin, other salicylates, and Tylenol (acetaminophen) are commonly used to treat fever, pain, and inflammation.
Cocaine is a highly addictive stimulant drug.
Propofol is an anesthetic and sedative given before or during surgery.
Intravenous (IV) epinephrine is used to treat severe allergic reactions.
Inhaled beta agonists (e.g., albuterol) are used to treat asthma.
Cyanide is a potentially lethal poison.
Methanol and ethylene glycol are toxic alcohols (highly poisonous).
What Are the Symptoms and Signs of Lactic Acidosis?
Symptoms and signs of lactic acidosis depend on the type, severity, and underlying cause.
Type A Lactic Acidosis
Symptoms/signs of septic shock include:
Fever and sweating
Confusion
Decreased urination
Flushed/warm skin that becomes cool and pale as the condition progresses
Low blood pressure
Fast heart and breathing rate
Hypovolemic shock symptoms and signs are similar to septic shock, although fever and warm skin are absent. Individuals with hypovolemic shock also have cool skin, dry eyes/mouth, and poor skin turgor (elasticity).
Symptoms/signs of cardiogenic shock include:
Cool extremities
Cyanosis (bluish-purple skin tint)
Low blood pressure
Weak pulses
Fast heart and breathing rate
Lung crackles (lung sounds that are a sign of fluid accumulation)
Swollen neck veins
Type B Lactic Acidosis
Symptoms of type B lactic acidosis may include:
Nausea or vomiting
Stomach pain
Muscle cramps or burning
Malaise or generalized weakness
Confusion or decreased alertness
Other symptoms may be present depending on the underlying cause and severity of the acidosis.
For example, classic symptoms of diabetic ketoacidosis include:
Excess thirst and urination
A pattern of fast, deep breathing (Kussmaul breathing)
A fruity breath odor
Learn More: Deeper Dive into Symptoms of Diabetic Ketoacidosis
How Lactic Acidosis Is Diagnosed
Lactic acidosis is diagnosed through three blood tests:
An arterial blood glass (ABG) revealing a pH level of less than 7.35 (indicating increased acidity in the body)
A basic metabolic panel (BMP) to calculate the anion blood gap, which is elevated in lactic acidosis
An increased blood lactate level
What Is a Normal Lactate Level?
A normal lactate level is between 0.5 and 1.8 millimoles per liter (mmol/L). An elevated lactate is between 2 and 5 mmol/L, whereas a severely elevated lactate level is greater than 5 mmol/L.
Learn More: Why Do You Need pH Balance?
How Lactic Acidosis Is Treated
Sorting out the type and cause of lactic acidosis is key to guiding treatment.
Type A Lactic Acidosis
The treatment of type A lactic acidosis aims to improve oxygen availability and correct the underlying cause (e.g., infection, blood or fluid loss, or the heart's poor pumping ability).
These interventions are performed in an intensive care unit (ICU) or coronary care unit (CCU) and may include:
Administering intravenous (through the vein) fluids to increase blood pressure
Administering blood transfusions to replace lost blood or increase oxygen delivery to organs
Administering a vasopressor like norepinephrine to increase blood pressure or an inotrope like dobutamine to improve the heart's pumping action
Administering medications that address the underlying cause—for example, antibiotics to kill a bacterial infection
Administering bicarbonate therapy to reverse blood acidity (this is a controversial practice reserved for severe cases of lactic acidosis)
Providing oxygen therapy, which may involve placing a person on a ventilator (breathing machine)
Keep in mind that temporary causes of type A lactic acidosis, namely overexercising, are usually treated at home with rest and fluids. In such cases, a person's liver and (to a lesser degree) kidneys eventually clear the lactate from the bloodstream.
Type B Lactic Acidosis
The treatment of type B lactic acidosis is geared towards the specific cause.
Examples of such interventions include:
Stopping the offending medication
Administering fluids and insulin intravenously in cases of diabetic ketoacidosis
Administering thiamine intravenously in cases of thiamine deficiency (e.g., chronic alcohol use disorder).
Treating a person's underlying cancer—for example, through radiation, surgery, or chemotherapy.
Learn More: Overview of Cancer Treatments
What’s the Outlook for Lactic Acidosis?
The greater the lactate level in hospitalized individuals with lactic acidosis, the higher the risk of death. As such, lactate levels are a marker of prognosis (disease outcome).
More specifically, since an increased lactate level can predict severe outcomes, including death, it's essential to obtain a blood lactate test early on when a person with a critical illness enters the emergency room or hospital.
In addition, blood lactate levels should be tracked (if elevated) and used as a resource when choosing therapies to optimize chances for a full recovery.
How to Prevent Lactic Acidosis
While there is no foolproof strategy to prevent lactic acidosis, practicing healthy lifestyle behaviors can help maintain the integrity of your liver and kidneys, which are crucial for lactate clearance. Moreover, a healthy lifestyle may help prevent specific underlying causes of lactic acidosis, like infection or cancer.
Such behaviors include:
Maintaining a healthy weight
Exercising regularly (under the guidance of a healthcare provider if you have a chronic condition)
Eating a well-balanced diet
Avoiding smoking and excessive alcohol consumption
Staying hydrated by drinking water throughout the day
Visiting a primary care provider for an annual check-up and updated vaccinations
Engaging in safe practices, like always wearing a seatbelt in a moving vehicle
Lastly, if you have a disease or are taking a medication that may cause lactic acidosis, please contact your healthcare provider for new or worrisome symptoms.
Summary
Lactic acidosis is characterized by increased lactate levels, an acidic product of anaerobic (without oxygen) metabolism. High lactate levels may occur with lactate overproduction, decreased lactate clearance, or both.
Lactic acidosis has multiple causes, including shock. Types of shock include septic (widespread infection), hypovolemic (loss of blood/fluid), and cardiogenic (heart malfunctioning) shock.
Excessive exercise is another cause of lactic acidosis. Unlike shock, though, which requires intensive hospital care, lactic acidosis from overexercising is not dangerous and resolves quickly with rest and hydration. Certain medications, liver disease, cancer, and HIV/AIDS, among many others, can also cause lactic acidosis.
Regarding a diagnosis, lactic acidosis requires blood tests that measure the lactate level and evaluate for acidity in the bloodstream. Treatment depends on the underlying cause and other factors, such as disease severity.
If you have concerns about developing lactic acidosis, speak with a healthcare provider. Early attention and treatment are key to managing this complex condition.
If you or a loved one has recently recovered from a serious illness associated with lactic acidosis, take time to review the next steps with your healthcare team carefully.
Read the original article on Verywell Health.
