Introduction

Brief overview of hypovolemia and dehydration

About 50 to 60 percent of your body consists of fluid, however, if you have hypovolemia, you lose more than 10% of the total volume of fluid within your body’s circulatory system.

Hypovolemia occurs when you don’t have enough fluid volume circulating in your body. The low volume of fluid includes blood and water in your circulatory system, with or without the lymphatic fluid.

Dehydration is the lack of enough water in your body. It is a state in which you lose significant body fluid, and as a result your body can’t function normally. It occurs when you lose more fluid than you consume.

It can also come about if you don't drink enough water, or if you’re taking a drug that increases your urine output.

Hypovolemia

Definition

Hypovolemia refers to a condition of low extracellular fluid volume, commonly occurring secondary to combined sodium and water loss.

Causes

Loss of blood or other body fluid causes hypovolemia. There are several ways that the body can lose blood or fluid including:

• Injury: accidental cutting or wounding which causes blood loss
• Illness: particularly with symptoms of persistent vomiting and diarrhoea
• Internal bleeding: a rudimentary condition that causes blood loss within your body
• Dehydration: absence of water and electrolyte intake decreases blood volume
• Excessive sweating: participating in strenuous activities that make you sweat for a long time, or a condition that causes you to sweat more than normal (hyperhidrosis)

Symptoms

Symptoms of hypovolemia differ depending on the severity. Signs of hypovolemia include:

• Dizziness when standing
• Dry skin and dry mouth
• Fatigue or weakness
• Muscle cramps
• Reduced urine output or darker than normal urine colour
• Confusion
• Rapid heartbeat
• Excessive sweating
• Losing consciousness
• Low blood pressure
• Low body temperature
• Cold, clammy skin

It is important to visit a healthcare practitioner if you experience any of these symptoms, especially after an injury.

Treatment

Immediate treatment leads to good results for people diagnosed with hypovolemia.

Intravenous fluid to replenish lost volume

The purpose of treatment for hypovolemia is to raise the amount of fluid in your body via fluid replacement. During this procedure, an intravenous tube is used to administer fluids into your vein. The fluid replaced can be different depending on what type of fluid your body needs:

• Blood transfusion: blood from a donor replaces lost blood in your body
• Crystalloid solution: tiny molecules of dissolved saline, or a combination of sodium, chloride, potassium, calcium and lactate

Addressing the underlying cause

In addition to fluid replacement, treating the cause of hypovolemia is important. Some of these causes include:

• Treating an infection, injury or illness
• Healing a wound
• Giving missing nutrients (such as sodium or electrolytes)

Dehydration

Definition

Dehydration refers to the loss of body water, with or without electrolytes, at a rate more than the body can replace it. 

Causes

• Reduced intake of water
• Losing water quickly through, sweating, vomiting and/or diarrhea
• Certain medications like diuretics, which can result in increased urination
• Engaging in strenuous exercise, especially in hot weather
• Drinking too much alcohol
• Diabetes

Symptoms

• Thirst
• Reduced urine output
• Sunken eyes
• Dry, wrinkled skin
• Deep, rapid breathing
• Headache, delirium and confusion
• Tiredness (fatigue)
• Dizziness, weakness and lightheadedness
• Dry mouth
• Muscle cramps
• Heat intolerance or chills
• Constipation
• Dark-coloredurine (normal urine should be a pale, clear colour)

Treatment

In most cases, dehydration can be treated at home, although severe cases may require hospitalisation.

Treatment of dehydration at home includes:

• Increasing fluid intake
• Intake of oral rehydration solutions

Hospital care may include:

• Fluids given intravenously
• Monitoring of electrolyte imbalance
• Adequate rest
• Electrolyte solutions, which may be helpful when taken as prescribed by the provider
• Slow increase in the amount of fluid and food consumed

FAQs

How does hypovolemia affect the body?

Your body needs a certain amount of fluid (blood) to keep your organs functioning. Like the plants in your garden, your body needs fluid to stay alive. If there is a drought and your garden doesn’t get enough water from rain, your plants will wilt. Your body needs fluids to keep you from wilting too. When you’re diagnosed with hypovolemia, your healthcare provider will give you supplemental fluids to replace the fluid you lost in the same way that you use a watering can to water the plants in your garden when it doesn’t rain.

Summary

The terms dehydration and hypovolemia are often used interchangeably, they represent distinct but interconnected concepts in medical terminology. While dehydration refers to a deficit of body water, hypovolemia denotes a decrease in the volume of circulating body fluid and electrolytes.

Understanding this crucial difference is vital for accurate diagnosis and effective treatment in clinical settings. By recognising the nuances between these two conditions, healthcare professionals can provide more targeted interventions, ultimately improving patient outcomes.