Lactic Acidosis

What is lactic acidosis?

Lactic acidosis is a buildup of lactic acid in your bloodstream. It happens when your body produces too much lactic acid and/or can’t metabolize enough of the lactic acid it produces.

Your liver and kidneys normally clear excess lactic acid from your body. But if there’s too much, or the organs are impaired, or both, they can’t keep up, and lactic acid builds up in your blood.

Moderate buildup of lactic acid in your blood is called hyperlactatemia. When it builds up enough to turn your body’s pH balance acidic, it’s called lactic acidosis.

Why does my body produce lactic acid?

Lactic acid, also called lactate, is a natural byproduct of cellular metabolism. Our cells convert glucose (sugar) to lactate to use for energy in a process called anaerobic glycolysis. They do this when they’re in need of immediate energy that can’t be supplied by oxygen.

Aerobic metabolism, which relies on oxygen, is our usual go-to for a steady energy supply, but anaerobic glycolysis is our emergency backup. We might need to tap it for a short burst of intense exercise when our muscles are oxygen-deprived. We also use it when medical conditions deprive our tissues of oxygen.

What happens during lactic acidosis?

What you may experience during lactic acidosis depends on how severe it is. Some people experience temporary lactic acidosis as a side effect of overexercising. This can make you feel sore for a while, but as long as your liver and kidneys are in good condition, they’ll eventually clear it.

It’s more serious when your body persistently produces too much lactic acid, or your liver and kidneys are consistently not functioning well enough to process it. This most often occurs in the context of illness. As your blood lactate levels continue to rise and pH levels fall, your cardiac output is increasingly suppressed. This can lead to organ failure and death.

What are the signs of lactic acidosis?

Early symptoms of lactic acidosis include:

• Nausea and vomiting.
• Exhaustion and fatigue.
• Fast, deep breathing (respiratory compensation).
• Muscle cramps and body aches.

More advanced symptoms may include:

• Increasing weakness and drowsiness.
• Delirium and confusion.
• Ataxia.
• Oliguria (low urine output).

You might also have symptoms of the underlying conditions causing lactic acidosis, such as sepsis, shock or liver failure. These symptoms may include:

• Low body temperature.
• Low blood pressure.
• Fever.
• Jaundice (a yellow tint to the skin and whites of the eyes).

What is the main cause of lactic acidosis?

There are many causes. The most common cause is low oxygen levels in your blood (hypoxemia) or in your tissues (hypoxia). This usually results from a medical condition.

Healthcare providers have divided lactic acidosis into types based on different causes:

Type A

Type A lactic acidosis occurs when your tissues are deprived of oxygen. This most often happens in severe medical illnesses. It can also happen temporarily from excessive exercise.

Diseases that cause the overproduction of lactate include:

• Pulmonary disorders that deprive the blood of sufficient oxygen levels.
• Circulatory disorders that deprive the tissues of oxygen via slow blood flow.
• Hemoglobin disorders that affect the ability of your red blood cells to carry oxygen.
• Septic, hypovolemic or cardiogenic shock.
• Intestinal ischemic syndrome.
• Chronic seizures and convulsions.
• Carbon monoxide poisoning.

Type B

Type B lactic acidosis occurs without hypoxemia or hypoxia. It has three subcategories.

Type B1 is caused by underlying diseases that inhibit your ability to metabolize lactate.

These may include:

• Liver disease.
• Kidney disease.
• Thiamine (vitamin B1) deficiency.
• Cancer.
• HIV/AIDS.
• Mitochondrial diseases.
• Diabetes-related ketoacidosis.
• Alcohol use disorder.

Type B2 occurs as a side effect of certain drugs and toxins, including:

• Cyanide poisoning.
• Carbon monoxide poisoning.
• Alcohol poisoning.
• Cocaine.
• Nucleoside reverse transcriptase inhibitors (antiretroviral therapy).
• Beta-adrenergic agonist inhalers.
• Epinephrine injection for severe allergic reactions.
• Linezolid, an antibiotic.
• Propofol, an anesthetic.
• Metformin, a drug used to treat diabetes.

Type B3 occurs from rare congenital deficiencies of specific enzymes required to metabolize lactate. These include:

• Glycogen storage disease.
• Fructose-1,6-diphosphatase deficiency.
• Pyruvate carboxylase deficiency.
• Pyruvate dehydrogenase deficiency.
• Oxidative phosphorylation deficiency.
• Methylmalonic aciduria.

D-lactic acidosis

Types A and B above refer to a buildup of L-lactate in your blood. L-lactate is the form of lactic acid that’s normally produced and metabolized by the human body.

Another, rare form of lactic acidosis occurs from a buildup of D-lactate. This type of lactic acid is produced by bacteria in your colon. The bacteria metabolize carbohydrates during digestion, and D-lactate is the byproduct.

D-lactic acidosis happens when there’s an overgrowth of these bacteria. The excess D-lactate is absorbed through your intestines into your bloodstream. D-lactate can’t be metabolized by your kidneys or liver, so it just continues to build up in your circulation. This is most typically a complication of short gut syndrome.

How is lactic acidosis diagnosed?

Lactic acidosis is defined by:

• Blood lactate levels above 4 mmol/L (millimoles per liter).
• Blood pH levels below 7.35.

Healthcare providers will measure these values by taking a sample of your blood and testing it.

What tests are used to diagnose lactic acidosis?

Tests to diagnose lactic acidosis include:

• Comprehensive metabolic panel (CMP). This standard blood test measures a variety of factors in your blood to find out basic information about your health.
• Blood lactate test. In addition to routine measurements taken in the CMP, your healthcare provider will specifically measure your blood lactate levels.
• Anion gap blood test. This test measures the pH balance and electrolyte balance in your blood based on values from your blood panel.
• Arterial blood gas test. This test measures the oxygen saturation in your arteries, as well as pH balance and electrolyte balance in your arterial blood.

How is lactic acidosis treated?

If you have transitory lactic acidosis from exertion, shivering or convulsions, this will pass with time. You can treat it at home with rest and hydration.

In a clinical setting, lactic acidosis is treated immediately with IV fluids and any other resuscitation that may be necessary, such as oxygen therapy.

After that, treatment depends on the cause. Your healthcare team will work to manage the underlying disease or toxicity that’s causing lactic acidosis, based on your symptoms.

If you show signs of low oxygen levels, your healthcare team will suspect type A causes — such as cardiac or respiratory failure, sepsis or shock — and treat these emergency conditions first.

In the absence of low oxygen findings, they’ll consider various type B causes and attend to those specifically.

What outcome can I expect if I have lactic acidosis?

Outcomes depend on the cause and how severe it is. Type A lactic acidosis — associated with sepsis, shock and/or impaired blood oxygen flow — is more critical. Other types of lactic acidosis may be milder and slower to onset, allowing more time and opportunity to intervene. In general, higher blood lactate levels correlate with higher mortality rates. But early and effective treatment can end in a full recovery.

A note from Cleveland Clinic

Lactic acidosis is one of several types of metabolic acidosis that occur when acids build up in your blood. In metabolic acidosis, normal metabolic processes that produce and manage acids in your body break down in some way. Normally, your liver and kidneys can help filter out excess acids, but if they aren’t in good working condition, they’ll be less fit to manage acidosis. Taking care of your liver and kidneys by staying hydrated and limiting alcohol and drug use can go a long way toward protecting your long-term health.