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# Lactic acidosis

Lactic acidosis is too much lactic acid in the blood; it usually means the tissues are not getting enough oxygen.

Updated 2026-10-31

## Structures involved

Tap one to see what it is and open it in 3D.

- [Liver](https://durgical.com/en/anatomy/liver/)
- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Spleen](https://durgical.com/en/anatomy/spleen/)
- [Pancreas](https://durgical.com/en/anatomy/pancreas/)
- [Stomach](https://durgical.com/en/anatomy/stomach/)

## In biochemistry

- [Glycolysis: Without oxygen (LDH) · Lactate dehydrogenase (without oxygen)](https://durgical.com/en/biochemistry/pathways/glycolysis/#paso-11)
- [Gluconeogenesis: Step 1 · Pyruvate carboxylase](https://durgical.com/en/biochemistry/pathways/gluconeogenesis/#paso-1)
- [Malate–aspartate shuttle: Step 1 · Malate dehydrogenase 1 (cytosolic, MDH1)](https://durgical.com/en/biochemistry/pathways/malate-aspartate-shuttle/#paso-1)
- [Ethanol metabolism: Step 4 · Citrate synthase (entry to the Krebs cycle)](https://durgical.com/en/biochemistry/pathways/ethanol-metabolism/#paso-4)
- [Alanine](https://durgical.com/en/biochemistry/molecules/alanine/)
- [Glucose 6-phosphate](https://durgical.com/en/biochemistry/molecules/glucose-6-phosphate/)
- [Pyruvate](https://durgical.com/en/biochemistry/molecules/pyruvate/)
- [Lactate](https://durgical.com/en/biochemistry/molecules/lactate/)
- [ATP (adenosine triphosphate)](https://durgical.com/en/biochemistry/molecules/atp/)
- [NAD⁺ (nicotinamide adenine dinucleotide)](https://durgical.com/en/biochemistry/molecules/nad/)
- [Pyruvate dehydrogenase complex (PDH)](https://durgical.com/en/biochemistry/enzymes/pyruvate-dehydrogenase-complex/)
- [Pyruvate carboxylase](https://durgical.com/en/biochemistry/enzymes/pyruvate-carboxylase/)
- [Fructose-1,6-bisphosphatase (FBPase-1)](https://durgical.com/en/biochemistry/enzymes/fructose-1-6-bisphosphatase/)
- [Glucose-6-phosphatase](https://durgical.com/en/biochemistry/enzymes/glucose-6-phosphatase/)
- [Cori cycle](https://durgical.com/en/biochemistry/topics/cori-cycle/)
- [Acid–base interpretation (step by step)](https://durgical.com/en/biochemistry/topics/acid-base-interpretation/)
- [Anion gap and delta ratio](https://durgical.com/en/biochemistry/topics/anion-gap-and-delta-ratio/)
- [pH, buffers and the Henderson–Hasselbalch equation](https://durgical.com/en/biochemistry/topics/ph-buffers-and-the-henderson-hasselbalch-equation/)
- [Exercise metabolism](https://durgical.com/en/biochemistry/topics/exercise-metabolism/)
- [Complex I (NADH dehydrogenase)](https://durgical.com/en/biochemistry/enzymes/complex-i/)
- [Complex III (cytochrome bc₁)](https://durgical.com/en/biochemistry/enzymes/complex-iii/)
- [Cytochrome c oxidase (complex IV)](https://durgical.com/en/biochemistry/enzymes/cytochrome-c-oxidase/)
- [Warburg effect (aerobic glycolysis in cancer)](https://durgical.com/en/biochemistry/topics/warburg-effect/)
- [Thiamine (vitamin B1)](https://durgical.com/en/biochemistry/molecules/thiamine/)

## In physiology

- [Metabolic acidosis, the anion gap and compensation](https://durgical.com/en/physiology/metabolic-acidosis-the-anion-gap-and-compensation/)
- [Mixed acid–base disorders](https://durgical.com/en/physiology/mixed-acid-base-disorders/)

## What it is

High anion gap metabolic acidosis from lactate buildup, usually 4–5 mmol/L or more with a low pH.

## Causes

- Type A (tissue hypoxia): septic, hypovolemic or cardiogenic shock; gut or limb ischemia; severe hypoxemia
- Type B (no hypoxia): metformin with kidney failure, liver failure, thiamine deficiency, blood cancers, toxins (alcohols, cyanide), inborn errors (PDH deficiency)
- D-lactic: short bowel with bacterial overgrowth

## Risk factors

- Sepsis and shock
- Metformin with low kidney function
- Alcohol use and malnutrition (thiamine deficiency)
- Liver failure

## Pathophysiology

Without oxygen the mitochondria cannot take NADH or pyruvate; lactate dehydrogenase turns pyruvate into lactate to regenerate NAD⁺ and glycolysis goes on. When production outpaces what the liver and kidney can recycle (Cori cycle), lactate and protons build up. If PDH fails (thiamine deficiency, arsenic, a genetic defect), pyruvate is also diverted to lactate.

## Classification

- Type A (hypoxia)
- Type B1 (underlying disease), B2 (drugs and toxins), B3 (inborn errors)

## Symptoms and signs

- Fast, deep breathing
- Nausea, vomiting, abdominal pain
- Weakness, confusion
- Signs of the underlying shock: low blood pressure, cold [skin](https://durgical.com/en/anatomy/skin/), little urine

## Red flags

- Lactate 4 mmol/L or more in an infection: treat as septic shock
- Abdominal pain out of proportion to the exam (gut ischemia)

## Diagnosis

**Clinical**
Look for the cause: perfusion, infection, drugs (metformin), alcohol, [liver](https://durgical.com/en/anatomy/liver/), malnutrition.

**Tests**
Arterial or venous blood lactate, gases (pH, bicarbonate), anion gap, [kidney](https://durgical.com/en/anatomy/kidney/) and liver tests, glucose, ketones, blood cultures; toxin levels if suspected. The lactate/pyruvate ratio helps in inborn errors.

**Imaging**
By suspected cause: contrast CT if gut ischemia is suspected, echocardiography in shock.

## Treatment

**Acute**
Treat the cause: restore perfusion (fluids, vasopressors), control the infection

**Medical**
Intravenous thiamine when deficiency is possible (alcohol, malnutrition)

**Procedure**
Hemodialysis for severe metformin-associated acidosis or with kidney failure

**Follow-up**
Repeat lactate to guide resuscitation

## Complications

- Multiple organ failure
- Arrhythmias from severe acidosis

## Prognosis

It depends on the cause; a lactate that fails to fall with treatment means higher mortality.

## Test yourself

Think of the answer, then tap the question to see it.

## What separates type A from type B lactic acidosis?

Type A comes from tissue oxygen lack; type B happens without hypoxia (drugs, liver, thiamine, inborn errors).

## Which vitamin is given in lactic acidosis in a patient with alcohol use disorder?

Thiamine (B1), the pyruvate dehydrogenase cofactor.

## Why do cells make lactate when oxygen is short?

To regenerate the NAD⁺ glycolysis needs at the GAPDH step.

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## Related conditions

- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)
- [Hypovolaemic shock](https://durgical.com/en/conditions/hypovolaemic-shock/)
- [Type 2 diabetes mellitus](https://durgical.com/en/conditions/type-2-diabetes-mellitus/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Lactic acidosis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000391.htm) (MedlinePlus, US National Library of Medicine, 2026); [Lactate Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/lactic-acid-test/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Source: https://durgical.com/en/conditions/lactic-acidosis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/lactic-acidosis/