Acid-Base Disorders – Causes, Symptoms, Diagnosis, Treatment

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 9 min read
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Acid-base disorders are disturbances in the homeostasis of hydrogen ion concentration in the plasma. Any process that increases the serum hydrogen ion concentration is an acidotic process. The term acidemia is used to describe serum that is abnormally acidic, and this can be due to...

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Article Summary

Acid-base disorders are disturbances in the homeostasis of hydrogen ion concentration in the plasma. Any process that increases the serum hydrogen ion concentration is an acidotic process. The term acidemia is used to describe serum that is abnormally acidic, and this can be due to respiratory acidosis, which involves changes in carbon dioxide, or metabolic acidosis that is influenced by decreased bicarbonate. Metabolic acidosis is...

Key Takeaways

  • This article explains Interpretation Steps in simple medical language.
  • This article explains Respiratory acidosis in simple medical language.
  • This article explains Metabolic acidosis in simple medical language.
  • This article explains Alkalosis in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
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Definition

Acid-base disorders are disturbances in the homeostasis of hydrogen ion concentration in the plasma. Any process that increases the serum hydrogen ion concentration is an acidotic process. The term acidemia is used to describe serum that is abnormally acidic, and this can be due to respiratory acidosis, which involves changes in carbon dioxide, or metabolic acidosis that is influenced by decreased bicarbonate. Metabolic acidosis is characterized by an increase in the hydrogen ion concentration in the systemic circulation that results in an abnormally low serum bicarbonate level. Metabolic acidosis signifies an underlying disorder that needs to be corrected to minimize morbidity and mortality. This activity describes the risk factors, evaluation, and management of metabolic acidosis and highlights the role of the interprofessional team in enhancing care delivery for affected patients.

Your blood needs the right balance of acidic and basic (alkaline) compounds to function properly. This is called the acid-base balance. Your kidneys and lungs work to maintain the acid-base balance. Even slight variations from the normal range can have significant effects on your vital organs. Acid and alkaline levels are measured on a pH scale. An increase in acidity causes pH levels to fall. An increase in alkaline causes pH levels to rise.

When the levels of acid in your blood are too high, it’s called acidosis. When your blood is too alkaline, it is called alkalosis. Respiratory acidosis and alkalosis are due to a problem with the lungs. Metabolic acidosis and alkalosis are due to a problem with the kidneys. Each of these conditions is caused by an underlying disease or disorder. Treatment depends on the cause.

Determining the type of metabolic acidosis can help clinicians narrow down the cause of the disturbance. Acidemia refers to a pH less than the normal range of 7.35 to 7.45. In addition, metabolic acidosis requires a bicarbonate value less than 24 mEq/L. Further classification of metabolic acidosis is based on the presence or absence of an anion gap, or concentration of unmeasured serum anions. Plasma neutrality dictates that anions must balance cations to maintain a neutral charge. Therefore, sodium (Na), the primary plasma cation, is balanced by the sum of the anions bicarbonate and chloride in addition to the unmeasured anions, which represent the anion gap. Unmeasured anions include lactate and acetoacetate, and these are often some of the main contributors to metabolic acidosis.[rx][rx][rx]

  • Anion gap (AG) = [Na] –([Cl] + [HCO3])

Anion gap metabolic acidosis is frequently due to anaerobic metabolism and lactic acid accumulation. While lactate is part of many mnemonics for metabolic acidosis, it is important to distinguish it is not a separate etiology, but rather a consequence of a condition.

Mnemonic for anion gap metabolic acidosis differential: CAT MUDPILES

  • C: Cyanide and carbon monoxide poisoning
  • A: Arsenic
  • T: Toluene
  • M: Methanol, Metformin
  • U: Uremia
  • D: DKA
  • P: Paraldehyde
  • I: Iron, INH
  • L: Lactate
  • E: Ethylene glycol
  • S: Salicylates

Non-gap metabolic acidosis is primarily due to the loss of bicarbonate, and the main causes of this condition are diarrhea and renal tubular acidosis. Additional and rarer etiologies include Addison’s disease, ureterosigmoid or pancreatic fistulas, acetazolamide use, and hyperalimentation through TPN initiation. GI and renal losses of bicarbonate can be distinguished via urine anion gap analysis:

  • Urine AG = Urine Na + Urine K – Urine Cl

A positive value is indicative of renal bicarbonate loss, such as renal tubular acidosis. Negative values are found with non-renal bicarbonate losses, such as diarrhea.

Interpretation Steps

Acid-base interpretation is crucial to identify and correct disturbances in acid-base equilibrium that have profound consequences on patient health. The following steps use lab values and equations to determine if a patient has metabolic acidosis and any additional acid-base disturbances.

Step 1: pH, determine if the acid-base status is acidemia or alkalemia

Blood pH is maintained within a narrow range for optimization of physiological functions. Acid-base equilibrium is achieved within a pH range of 7.35 to 7.45. Blood pH distinguishes between acidemia (pH less than 7.35) and alkalemia (pH greater than 7.45)

Step 2: CO2, determine if the disturbance is metabolic or respiratory

The pCO2 determines whether an acidosis is respiratory or metabolic in origin. For respiratory acidosis, the pCO2 is greater than 40 to 45 due to decreased ventilation. Metabolic acidosis is due to alterations in bicarbonate, so the pCO2 is less than 40 since it is not the cause of the primary acid-base disturbance. In metabolic acidosis, the distinguishing lab value is a decreased bicarbonate (normal range 21 to 28 mEq/L).

Step 3: Determine if there is an anion gap or non-anion gap metabolic acidosis

  • AG= Na – (Cl + HCO3)

The normal anion gap is 12. Therefore, values greater than 12 define an anion gap metabolic acidosis.

Step 4: CO2, assess if respiratory compensation is appropriate

Respiratory compensation is the physiologic mechanism to help normalize metabolic acidosis, however, compensation never completely corrects an acidemia. It is important to determine if there is adequate respiratory compensation or if there is another underlying respiratory acid-base disturbance. Winter’s formula is the equation used to determine the expected CO2 for adequate compensation.

  • Winter’s formula: Expected CO2 = (Bicarbonate x 1.5) + 8 +/- 2

If the patient’s pCO2 is within the predicted range, then there is no additional respiratory disturbance. If the pCO2 is greater than expected, this indicates an additional respiratory acidosis. If the pCO2 is less than expected, there is an additional respiratory alkalosis occurring.

Step 5: Evaluate for additional metabolic disturbances

A delta gap must be determined if an anion gap is present.

  • Delta gap = Delta AG – Delta HCO3 = (AG-12) – (24-bicarbonate)

If the gap is less than -6, then a NAGMA is present.

If the gap is greater than 6, then an underlying metabolic alkalosis is present.

If the gap is between -6 and 6 then only an anion gap acidosis exists.

Respiratory acidosis

When you breathe, your lungs remove excess carbon dioxide from your body. When they cannot do so, your blood and other fluids become too acidic.

Symptoms of respiratory acidosis

Symptoms may include fatigue, shortness of breath, and confusion.

Causes of respiratory acidosis

There are several different causes of respiratory acidosis including:

  • chest deformities or injuries
  • chronic lung and airway diseases
  • overuse of sedatives
  • obesity

Types of respiratory acidosis

There are no noticeable symptoms of chronic respiratory acidosis. This is due to the fact that your blood slowly becomes acidic and your kidneys adjust to compensate, returning your blood to a normal pH balance.

Acute respiratory acidosis comes on suddenly, leaving the kidneys no time to adjust. Those with chronic respiratory acidosis may experience acute respiratory acidosis due to another illness that causes the condition to worsen.

Diagnosis of respiratory acidosis

A complete physical examination is necessary. Diagnostic testing may include:

  • arterial blood gas test
  • metabolic panel
  • pulmonary function test
  • chest X-ray

Treatment of respiratory acidosis

A doctor should be seen immediately to treat acute respiratory acidosis, as this can be a life-threatening condition. Treatment is targeted to the cause.

Bronchodilator medications may be given to correct some forms of airway obstruction. If your blood oxygen level is too low, you may require oxygen. Noninvasive positive pressure ventilation or a breathing machine may be necessary.

To treat chronic respiratory acidosis, the underlying cause needs to be determined in order for proper treatment to take place. The cause could be an organ deformity, an infection, or some type of pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।" data-rx-term="inflammation" data-rx-definition="Inflammation is the body’s response to injury, infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।">inflammation. Each cause may require a different treatment ranging from antibiotics to a breathing machine.

In either case, if you smoke, you will be advised to stop.

Complications of respiratory acidosis

Respiratory acidosis is serious and requires immediate medical attention. Potential complications of untreated respiratory acidosis include respiratory failure, organ failure, and shock.

Preventing respiratory acidosis

You can take steps to help prevent some of the conditions that lead to respiratory acidosis. Maintain a healthy weight. Take sedatives only under strict doctor supervision and never combine them with alcohol. Do not smoke.

Metabolic acidosis

Metabolic acidosis occurs either when your body produces too much acid, or when your kidneys are unable to remove it properly.

Symptoms of metabolic acidosis

Symptoms can include rapid breathing, fatigue, and confusion.

Causes of metabolic acidosis

There are three main types of metabolic acidosis. Diabetic acidosis, or diabetic ketoacidosis, is a buildup of ketone bodies. This is usually due to uncontrolled type 1 insulin is low or not working well. সহজ বাংলা: রক্তে চিনি বেশি থাকার রোগ।" data-rx-term="diabetes" data-rx-definition="Diabetes is a condition where blood sugar stays too high because insulin is low or not working well. সহজ বাংলা: রক্তে চিনি বেশি থাকার রোগ।">diabetes. Hyperchloremic acidosis is when your body loses too much sodium bicarbonate, often after severe diarrhea.

Lactic acidosis is when too much lactic acid builds up. This can be due to:

  • prolonged exercise
  • lack of oxygen
  • certain medications, including salicylates
  • low blood sugar, or hypoglycemia
  • alcohol
  • seizures
  • liver failure
  • cancer
  • kidney disease
  • severe dehydration
  • poisoning from consuming too much aspirin, ethylene glycol, and methanol

Diagnosing metabolic acidosis

Diagnostic testing may include serum electrolytes, urine pH, and arterial blood gases. Once acidosis is confirmed, other tests may be necessary to pinpoint the cause.

Treatment of metabolic acidosis

The underlying condition behind the acidosis must be treated. In some cases, sodium bicarbonate is prescribed to return the blood to a normal pH.

Complications of metabolic acidosis

Severe cases can lead to shock and can be life-threatening.

Alkalosis

Alkalosis is when alkaline levels are too high due to decreased carbon dioxide or increased bicarbonate. There are five kinds of alkalosis.

Symptoms of alkalosis

Symptoms of alkalosis may include:

  • muscle twitching, hand tremor, muscle spasms
  • numbness and tingling
  • nausea
  • vomiting
  • lightheadedness
  • confusion

Causes and types of alkalosis

Respiratory alkalosis is when your blood has low levels of carbon dioxide. This can be caused by a number of factors, including:

  • lack of oxygen
  • high altitude
  • fever
  • lung disease
  • liver disease
  • salicylate poisoning

When you have alkalosis your carbon dioxide levels are low. This causes your body to release more bicarbonate to return your blood pH level back to normal. This is called compensated alkalosis. Your blood pH levels will test normal, however, your kidneys are releasing more bicarbonate, compensating for the lower levels of carbon dioxide.

When your blood has too much bicarbonate, it is called metabolic alkalosis. This can happen from prolonged vomiting. Prolonged vomiting can also make you lose too much chloride. This is called hypochloremic alkalosis. Some diuretic medicines can cause you to lose too much potassium. This is called hypokalemic alkalosis.

Diagnosing alkalosis

Along with a physical exam, diagnostic testing for alkalosis may include a metabolic panel, blood gas analysis, urinalysis, and urine pH.

Treatment for alkalosis

Some medications (such as chloride and potassium) can help correct chemical losses. Further treatment will depend on the cause. Your physician will need to monitor your vital signs and create a proper plan to correct your pH imbalance.

Complications of alkalosis

In severe cases, alkalosis can lead to heart arrhythmias or coma.

References

 

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Care roadmap for: Acid-Base Disorders – Causes, Symptoms, Diagnosis, Treatment

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

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