Metabolic acidosis is a condition that occurs when there is too much acid in the body’s fluids. This can happen in one of two main ways: either the body is producing or ingesting too much acid, or the kidneys are not removing enough acid from the body, or the body is losing too much of its natural base (bicarbonate). This accumulation of acid causes the blood’s pH to drop, making it acidic.

To understand this, it is helpful to use an analogy. Think of your blood’s pH as the water in a swimming pool, which must be kept perfectly balanced to be safe. Your body’s primary defense against acid is a natural buffer system, with a compound called bicarbonate acting as the primary player. Bicarbonate is like the “baking soda” that you would add to the pool to instantly neutralize any acid that gets in (like acidic ‘chlorine’). This keeps the water comfortable and stable.

Metabolic acidosis is what happens when this system is overwhelmed.

• Scenario 1: Increased Acid Production. It’s as if a large amount of strong acid is suddenly dumped into the pool. There isn’t enough “baking soda” (bicarbonate) available to neutralize it all, and the water quickly becomes acidic. This is what happens in conditions like diabetic ketoacidosis or lactic acidosis.
• Scenario 2: Bicarbonate Loss. It’s as if someone opened a valve and drained all the “baking soda” out of the pool. Even the normal amount of acid produced by daily metabolism is now enough to make the water acidic because the primary buffer is gone. This is what happens with severe diarrhea.

When the blood becomes too acidic, it interferes with the function of vital enzymes and proteins, disrupts heart and muscle contractions, and can lead to a cascade of organ failure.

In my experience, metabolic acidosis is often discovered during blood tests in patients who are severely ill or dehydrated, it’s a key clue that the body is under major stress.

The causes of metabolic acidosis are diverse. To identify the root cause, doctors use a calculation derived from a blood test called the anion gap. Explaining this simply, the anion gap helps a doctor determine if the acidosis is caused by the addition of an abnormal acid or the loss of the base, bicarbonate.

High Anion Gap Metabolic Acidosis (HAGMA)

This type is caused by adding acid to the body. The mnemonic “GOLDMARK” is often used to remember the common causes:

• G – Glycols (ethylene glycol from antifreeze, propylene glycol).
• O – Oxyproline (a byproduct of excessive acetaminophen/Tylenol use).
• L – L-Lactate (from lactic acidosis).
• D – D-Lactate (a rare form of lactic acidosis).
• M – Methanol (from contaminated alcohol).
• A – Aspirin (salicylate overdose).
• R – Renal Failure (the kidneys fail to excrete normal metabolic acids).
• K – Ketoacidosis (from diabetes, starvation, or alcoholism).

Of these, the most common causes seen in a hospital setting are diabetic ketoacidosis, lactic acidosis, and kidney failure.

Normal Anion Gap Metabolic Acidosis (NAGMA)

This type is caused by the loss of bicarbonate from the body. The most common causes are:

• Gastrointestinal Bicarbonate Loss: Severe, prolonged diarrhea is the leading cause. The intestinal fluid is rich in bicarbonate, and losing large amounts in the stool can lead to acidosis.
• Renal (Kidney) Bicarbonate Loss: A group of kidney disorders known as renal tubular acidosis (RTA) can prevent the kidneys from properly reabsorbing bicarbonate back into the blood.

Clinically, when I see metabolic acidosis, I immediately start searching for these root causes, especially in diabetic patients or those with suspected poisoning or kidney issues.

A person develops metabolic acidosis due to another underlying condition or situation that affects the body’s acid–base balance.

You are at high risk of developing metabolic acidosis if you have:

• Uncontrolled Type 1 Diabetes: This is the primary risk factor for developing diabetic ketoacidosis (DKA). When there is not enough insulin, the body cannot use glucose for energy and begins to break down fat, producing acidic ketones as a byproduct.
• Chronic Kidney Disease (CKD): As kidney function declines, the ability to excrete acid and regulate bicarbonate is impaired, leading to a slow, chronic metabolic acidosis that can worsen acutely during illness.
• Conditions that Cause Shock or Sepsis: Any severe infection, trauma, or heart failure can lead to poor oxygen delivery to the tissues, causing lactic acidosis.
• Severe, prolonged diarrhea.
• Chronic Alcoholism.
• Ingesting certain poisons, like methanol or antifreeze.

Patients often ask if they could have prevented it. I explain that while prevention depends on the cause, staying hydrated, managing diabetes, and avoiding harmful substances are key protective steps.

Symptoms can range from mild to life-threatening, depending on how quickly the acidosis develops and how severe it becomes. In many cases, symptoms reflect the underlying disease more than the acidosis itself.

The single most important and characteristic sign of severe metabolic acidosis is a change in breathing:

• Rapid, Deep Breathing (Kussmaul Respirations): This is not a sign of a lung problem but is the body’s powerful compensatory mechanism. The lungs are trying to “blow off” as much carbon dioxide (which forms carbonic acid in the blood) as possible in a desperate attempt to counteract the metabolic acid and raise the blood’s pH.

Other general symptoms of acidosis include:

• Nausea and vomiting.
• Headache.
• Profound weakness and fatigue.
• Altered Mental Status: This is a major red flag indicating the acidosis is affecting the brain. It can range from confusion and drowsiness to stupor and, eventually, coma.
• In diabetic ketoacidosis, a person’s breath may have a distinct fruity or sweet smell due to the ketones.

In chronic, milder acidosis (seen in kidney disease), the main symptoms may be more subtle, such as bone pain or muscle wasting.

I’ve often seen patients with undiagnosed metabolic acidosis present with labored breathing and mental fog, it’s the body’s way of signaling an internal chemical emergency.

Metabolic acidosis is diagnosed through blood tests that assess the acid-base balance, along with tests to identify the underlying cause.

• Clinical Suspicion: A doctor will suspect metabolic acidosis in any critically ill patient who presents with shock, altered mental status, or signs of severe infection.
• Key Laboratory Tests: The diagnosis is confirmed with specific blood tests.
  • Arterial Blood Gas (ABG): This is the definitive test. A blood sample is drawn from an artery (usually in the wrist) and analyzed immediately. This test provides a direct measurement of the blood’s pH, and levels of oxygen, carbon dioxide, and bicarbonate. A low pH (below 7.35) and a low bicarbonate level confirm a diagnosis of metabolic acidosis.
  • Blood Chemistry Panel: A standard blood test is used to measure electrolytes (sodium, potassium, chloride), blood urea nitrogen (BUN), and creatinine (to assess kidney function), and to calculate the anion gap.
• Finding the Cause: The next step is a rapid search for the underlying cause:
  • Checking blood or urine for ketones (for DKA).
  • Measuring blood lactate levels (for lactic acidosis).
  • Taking a history for potential toxin ingestion.
  • Looking for a source of infection.

In my practice, calculating the anion gap helps me narrow down the cause, whether it’s ketoacidosis, kidney failure, or toxin ingestion. It’s like following chemical footprints to the source.

Severe metabolic acidosis is a life-threatening medical emergency with a high mortality rate. Treatment is urgent and focuses on supporting the patient’s vital functions while aggressively treating the root cause.

1. Treat the Underlying Cause

This is the absolute cornerstone of all treatment. The acidosis will not resolve until the root problem that is generating the acid or causing the loss of bicarbonate is fixed.

• For diabetic ketoacidosis, the treatment is insulin and intravenous fluids.
• For septic shock, the treatment is powerful IV antibiotics and circulatory support.
• For kidney failure, the treatment is dialysis.
• For toxic ingestions, treatment may include specific antidotes and emergency dialysis.
• For diarrhea, the treatment is rehydration with fluids and electrolytes.

2. Supportive Care

While the cause is being treated, the patient will receive intensive supportive care in an ICU. This can include IV fluids, oxygen therapy, and medications to support blood pressure.

3. Bicarbonate Therapy

While it may seem logical to give an alkali-like sodium bicarbonate to directly neutralize the acid in the blood, this approach is controversial and generally not recommended except in cases of extremely severe, life-threatening acidosis (e.g., a pH below 7.1). It does not fix the underlying problem of lactate production, and it can have its own side effects, such as fluid overload and electrolyte shifts.

I always explain that fixing metabolic acidosis isn’t about giving acid blockers, it’s about correcting what threw the body out of balance in the first place.

Metabolic acidosis is not a disease but a critical metabolic alarm bell. It signals that the body’s cells are in a state of severe distress, either starving for oxygen or unable to use it properly. It is an ominous sign that arises as a complication of life-threatening conditions like sepsis, shock, or severe organ failure. The symptoms of metabolic acidosis, like rapid breathing and confusion, are signs of a grave medical emergency. Patients often find relief knowing that once the cause is treated, the acidosis usually corrects itself, with the body naturally returning to its balanced state.

Merck Manual Professional Version. (2023). Metabolic Acidosis. Retrieved from https://www.merckmanuals.com/professional/endocrine-and-metabolic-disorders/acid-base-regulation-and-disorders/metabolic-acidosis

National Kidney Foundation. (2022). Metabolic Acidosis. Retrieved from https://www.kidney.org/atoz/content/metabolic-acidosis

American Diabetes Association. (n.d.). DKA (Ketoacidosis) & Ketones. Retrieved from https://diabetes.org/living-with-diabetes/complications/dka-ketoacidosis-ketones