Introduction

The body fluids such as blood have a pH maintained within the normal range of 7.35-7.45. Metabolic alkalosis is an acid-base disorder where the pH is raised beyond the upper normal limit (7.45). It happens due to increases in bicarbonate ion concentration.

Metabolic alkalosis happens due to accumulation of bicarbonate ions in the body. This can be as a result of:

•  Loss of protons (hydrogen ions).
•  The kidneys retaining bicarbonate.
•  Intracellular shift of protons.
•  Administration of base (alkali).

Metabolic alkalosis occurs in various health conditions. The difference between the actual bicarbonate concentration and the expected bicarbonate concentration is used to determine how severe the condition is.

 

 Risk Factors

What are the risk factors for metabolic alkalosis?

•  Vomiting.
•  Dehydration.
•  Critical illnesses.
•  Bulimia nervosa.
•  Taking medications such as laxatives for loss of weight.

 

 Causes

What are the causes of metabolic alkalosis?

There are several causes of metabolic alkalosis. They can be categorized into:

Medications. Taking excessive amounts of the following medicines can lead to metabolic alkalosis:

• Baking soda.
• Diuretics.
• Steroids.
• Antacids.

 

Health conditions. There are various medical conditions which are associated with metabolic alkalosis. They include:

•  Dehydration.
•  Hyperaldosteronism.
•  Recurrent vomiting.
• Electrolyte imbalances.
•  Cystic fibrosis.

 

 Signs & Symptoms

What are the signs and symptoms associated with metabolic alkalosis?

Common signs of metabolic alkalosis are:

• Fatigue.
• Coma.
• Seizures.
• Arrhythmia.
• Muscle cramps.
• Irritability.
• Confusion.
• Muscle spasms.
• Tremor.
• Numbness.

 

Types

What are the most common types of metabolic alkalosis?

Thera are two types of metabolic alkalosis. These are:

•  Chloride-responsive alkalosis.
• Chloride-resistant alkalosis.

 

 Chloride-responsive alkalosis

It occurs due to loss of protons through dehydration or vomiting.

 

Chloride-resistant alkalosis

• It happens due to:

1.   Bicarbonate retention by the body.
2.   Intracellular shift of protons.

 

 Diagnostic Procedures & Tests

How is metabolic alkalosis diagnosed?

• Review of medical history.
• Clinical examination.
• Blood tests to quantify:

1.  Electrolyte levels.
2.  Acid-base balance.
3.  Arterial blood gases (ABGs).

• Urinalysis.
• Electrocardiogram.

 

 Treatment and Management

How is metabolic alkalosis treated?

• Treat the cause of metabolic alkalosis. For example, if it is caused by diuretic agents, then administration of these class of drugs must be stopped.
• The deficiency that impairs renal bicarbonate excretion must be corrected. Administer chloride or potassium to help with this.
• Extracellular volume expansion using normal saline and if hypokalemia is present, add potassium chloride (KCl).
• Supportive measures such as monitoring the patient.
• Avoid hyperventilating. Rapid respiratory rate leads to worsening of alkalaemia.

 

 Complications

What are the complications of metabolic alkalosis?

Metabolic alkalosis is associated with complications such as:

•  Central nervous system;

1.  Confusion.
2. Reduced cerebral blood flow.
3. Neuromuscular excitability.

 

• Respiratory system;

1. Increased ventilation-perfusion mismatch.
2. Hypoventilation.
3. Pulmonary microatelectasis.

 

• Cardiovascular system;

1. Abnormal heart rhythms.
2. Decreased myocardial contractility.

 

Prevention

How do we prevent metabolic alkalosis?

Treatment of the underlying cause is one of the strategies to prevent development of metabolic alkalosis.