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Acid-base Disorders


You might have heard about the terms acids and bases around you. The word “pH” is the scale used for classifying acids and bases. “ pH” is the potential of hydrogen and is the negative logarithm of hydrogen ions (pH = - log10 [H+]), which means an increase in pH would indicate a decrease in hydrogen ions and vice versa. The substances which have more hydrogen ions that they can donate are called acids, and they are said to have a low Ph, while the substances that can accept hydrogen ions are called bases and are said to have a high pH. The fluids inside your body also have a pH level, according to which they are classified as acids and bases. This pH level needs to remain at the optimum level so that the physiologic processes in your body can occur and your body can function normally. Any change in the amounts of acids and bases can alter this pH level resulting in the disruption of the body’s physiologic processes, which will be evident clinically. 

The optimum pH of the body is tightly regulated between 7.35 to 7.45. The partial pressure of carbon dioxide is PCO2= 35-45 mmHg (body's acid), and the concentration of bicarbonate (body’s base) in the body is HCO3- = 22-26 mEq/L. 

If this pH level decreases, you are said to have acidosis in your body, and if the pH level increases, you are said to have alkalosis in your body. If the problem is due to PCO2, it is respiratory acidosis or alkalosis. If the problem is due to the HCO3, it is metabolic acidosis or alkalosis. Whether it is acidosis or alkalosis, it will have consequences evident clinically. 

Our body is regulated by the homeostatic system, which means that there are mechanisms in the body that try to keep the general conditions of the body at optimum levels so that it works normally. So for acid-base imbalance, there is a buffer system in our body that tries to bring back the pH to normal levels whenever there is a disturbance. The buffer systems of the body are :

  • The Carbonic acid bicarbonate buffer system  
  • The Phosphate buffer system 
  • The Protein buffer system

Types And Causes

Four main types of these disorders can occur separately or simultaneously;

  • Metabolic Acidosis
  • Metabolic Alkalosis
  • Respiratory Acidosis
  • Respiratory Alkalosis

Metabolic Acidosis: The body has decreased bicarbonates (less than 22 mEq/L ) in metabolic acidosis and pH less than 7.35. It can happen due to any of the three root causes: 

  • Increased acid production by the body or the addition of acids from outside. 
  • Loss of bicarbonate ions due to any reason
  •  When kidneys fail to excrete acids. It can be due to underlying diseases like;
  • Diabetic ketoacidosis.
  • Severe diarrhea (loss of HCO3).
  • Hypoaldosteronism.
  • Acute renal failure (which causes failure to excrete H+).
  • Accumulation of acids.
  • Lactic acidosis
  • Intoxication: Salicylates, methanol, ethylene glycol, formaldehyde, carbon monoxide

 Metabolic Alkalosis: In metabolic alkalosis, the body has decreased acids and pH above 7.45. The primary problem is due to the increase in serum bicarbonate (HCO3-) concentration (more than 26mEq/L), which can be either due to a loss of H+(acid) from the body or a gain in HCO3-(base). It can be due to the diseases like;

  • Severe vomiting resulting in loss of stomach acid
  • heavy ingestion of antacids.
  • Severe dehydration.
  • Excess antacids & alkaline drugs.
  • Hyperaldosteronism

Respiratory Acidosis: in this condition, there is an increase in the concentration of carbon dioxide ( more than 45 mm/hg) in the body due to the lung's improper function and hypoventilation. The carbon dioxide that usually leaves the body through exhalation cannot exit the body, and its retention leads to acidosis. The diseases causing respiratory acidosis are;

  • CNS depression (anesthesia).
  • Respiratory muscle paralysis
  • Diaphragm paralysis, 
  • Rib fractures, 
  • Obstructive lung diseases, e.g., Emphysema.
  • Pulmonary edema.

Respiratory Alkalosis: In this condition, there is a decrease in the concentration of carbon dioxide ( less than 35 mm/hg) in the body due to the lung's improper function and hyperventilation. Excess carbon dioxide leaves the body due to increased and rapid exhalation. The diseases causing respiratory alkalosis include;

  • High altitude (Due to oxygen deficiency)
  • Hysterical.
  • Anorexia nervosa.
  • Early salicylate intoxication.


Acid-base disorders can occur in a variety of diseases. So wherever these diseases prevail, acid-base disorders would be seen more. They are especially prevalent in patients with chronic kidney diseases

Risk Factors

You might get an acid-base disturbance if you have one or more of the following risk factors;

  • Excess alcohol use
  • Having Diabetes
  • Having a Renal disease
  • Suffering from a Liver disease
  • Having a Lung disease
  • Seizures
  • Neuromuscular disorders
  • Severe obesity
  • Endocrine disorders
  • Gastrointestinal diseases leading to severe vomiting
  • Mental disorders like panic disorder, mania, anxiety
  • Living at high altitudes

Signs And Symptoms

Having one or more of the following signs and symptoms can point towards an acid-base disorder;

Acidosis causes;

Alkalosis causes;

  • Numbness or abnormal sensations, 
  • Neuromuscular irritability, 
  • Tetany, 
  • Abnormal heart rhythms
  • Coma 
  • Seizures 
  • Confusion
  • Convulsions
  • Loss of consciousness
  • Death


In patients presenting to the emergency department or clinics with diseases that can lead to acid-base problems, the most important test to be performed is Arterial blood Gases (ABGs) which show concentrations of carbon dioxide, bicarbonate ions, and pH, which are necessary to diagnose an acid-base disorder.

Abnormal pH is <7.35 or >7.45

If PCO2>45 = Respiratory acidosis

If PCO2<35= Respiratory alkalosis

If HCO3-< 22= Metabolic acidosis.

If HCO3-> 26 = metabolic alkalosis.

Other helpful tests to find out the root cause and levels of other chemicals in the body are;

·         CBC (Complete Blood Count)

·         Serum Electrolytes

·         Serum Lactate levels

·         Serum Ketone levels

·         Urinalysis Complete

·         Salicylate or Iron levels or Toxicology Screen

·         ECG (Electrocardiogram) to check for heart rhythms

·         Radiographs, CT scans, MRI scans of abdomen to see kidney status.

·         Radiographs, CT scans, MRI scans of the chest to diagnose lung conditions

·         Pulmonary function tests

·         Capnography

·         Nerve muscle studies

Differential Diagnosis

The following disorders can be related to acid-base disorders and should be ruled out:


Treatment is focused on the type of disorder, the underlying condition, and the correction of the derangements caused by them.

For treating metabolic acidosis, bicarbonate therapy is usually given intravenously. The sooner you receive treatment, the better. Other treatments commonly used include detoxification in case of drug or alcohol poisoning, insulin administration in diabetic ketoacidosis, and intravenous fluids. 

For treating metabolic alkalosis, a trial of chloride-rich fluid can be given. To balance your blood pH levels if you're suffering from metabolic alkalosis, drink plenty of water and electrolytes. This can be achieved by consuming sodium and potassium-rich drinks. 

For treating respiratory acidosis, artificial ventilation or oxygen can be given. Your doctor may also prescribe therapies to help with breathing and medications that help open the lungs' passages. In cases of acute respiratory acidosis, noninvasive positive-pressure ventilation (Bi-PAP) may also be provided that allows breathing immediately. In more serious cases, mechanical ventilation to improve breathing by placing a tube into the airway is sometimes used. 

 Reassurance and breathing into a paper bag can be done to treat respiratory alkalosis.  The first step is to breathe and receive enough oxygen when treating respiratory alkalosis. If you're hyperventilating, slowing down your breathing, breathing calmly, and reducing anxiety will help you restore your oxygen levels.


The prognosis depends on the severity of the underlying condition causing the disorder. A better outcome is expected for the patients brought in time, and the diagnosis is made. Age factors, available facilities, and comorbid conditions are also important in the prognosis.


Since acid-base disorder occurs due to other diseases so your doctor may guide you about the possible chances of you getting the complications and how to prevent them. You should learn well about your disease. Be vigilant for your follow-ups and medicines' regularity. You should know well about the factors that can cause emergency visits and endanger your life. Apart from this, try to maintain healthy habits of taking proper well-balanced meals and regular exercise. Stay stress-free by adopting relaxation techniques. Join support groups to know more and more about your disease and be familiar with other patients' life. 


Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on April 28th, 2023.