IV therapy is an essential form of medical care, used to treat countless patients on a daily basis. It involves the transfusion of fluids directly into the body via an IV line, and a wide range of different IV fluids may be used, from simple saline solution to dextrose, lactated Ringers, and more.

We can divide IV fluids into three main categories: isotonic, hypotonic, and hypertonic. Each category is different, with its own distinctive features and uses. In this guide, we’ll take a closer look at isotonic IV fluids, hypotonic IV fluids, and hypertonic IV fluids to help you understand the difference, as well as providing some examples from each category.

What Are the Three Categories or Types of IV Fluids?

IV fluids, or intravenous fluids, are a family of fluids that are used during IV therapy. They can have various purposes, from restoring electrolytes and fluid levels in someone who is dehydrated to maintaining normal fluid volume in a patient undergoing some form of surgery or treatment. There are three types of fluids: isotonic, hypotonic, and hypertonic.

1. Isotonic Fluids

Let’s start off with isotonic fluids. We can easily work out what this kind of fluid is based on its name. “Tonic” simply means “concentration of a solution”, while “Iso” means “the same or equal”. 

Therefore, an isotonic solution is one that has a similar concentration of solutes (dissolved particles) as the blood. Because the concentration of an isotonic fluid is so similar to blood, the fluid should stay around the intravascular space and won’t move around much through osmosis. 

Some examples of isotonic fluids include normal saline solution and lactated Ringers, and these kinds of fluids are generally used to correct fluid volume deficits, to replace sodium losses, or to raise blood pressure. 

However, it’s important to use isotonic fluids with caution, as excess infusion could lead to excessive fluid volume. In addition, these fluids should not be used for patients with heart failure, renal impairment, and certain other conditions.

2. Hypotonic Fluids

Next, we’ll take a closer look at hypotonic fluids. Once again, we can break down the name to work out the definition of these kinds of fluids. We already know what “Tonic” means, and “Hypo” refers to something that is “less or under”. 

Therefore, a hypotonic fluid is one that has a relatively low concentration of solutes when compared to blood. This leads to water moving via osmosis from the intravascular area into the intracellular space. In other words, it causes water to enter cells.

A few examples of hypotonic IV fluids include half normal saline, quarter normal saline, and 2.5% dextrose solution. These fluids are useful for rehydrating cells and treating dehydration in general.

There are, however, some risks associated with these fluids. They should not be given to patients who are at risk of high cranial pressure, nor should they be given to patients with large burn wounds or trauma, as this may lower the fluid volume and interfere with the healing process.

3. Hypertonic Fluids

Finally, we have hypertonic fluids. The word “Hyper” refers to something that is “more or above”, so we can infer that hypertonic fluids are those that have a higher concentration of solutes when compared to blood.

What this means is that, when infused, hypertonic fluids create high concentrations of solutes around the intravascular space compared to the cells surrounding them. This leads to water actually draining out of the cells and back into the intravascular space.

Some examples of hypertonic IV fluids include 3% sodium chloride, 5% sodium chloride, 50% and 20% dextrose. Such fluids can be very useful for treating certain specific conditions, like ketosis, hyponatremia, or hypoglycemia.

However, the usage of hypertonic fluids must be done with great care. They could cause fluid overload in the patient and there may be a risk of pulmonary edema. Nurses should monitor the patient for any breathing difficulties or high blood pressure levels.

What Are the Different IV Solutions in Each Category?

Next, we’ll take a look at some examples of isotonic, hypotonic, and hypertonic IV fluids. We’ll look at each fluid in detail, covering its contents, uses, and any potential considerations or risks that medical personnel need to be aware of.

1. Isotonic IV Fluids 

The majority of IV fluids are isotonic, and some of the most commonly-used IV fluids, like normal saline solution and lactated Ringers, fall into this category. 

0.9% Normal Saline Solution (NaCl 0.9%) 

Normal saline solution, also known as 0.9% NaCl or NSS, is one of the most common kinds of IV fluids used in hospitals, clinics, and other medical locations all over the globe. It consists of water, sodium, and chloride. 

It’s known as “normal” saline solution, due to the fact that the level of sodium chloride within NSS is similar to the usual levels of sodium chloride inside the intravascular space. 

This is one of the most useful solutions for expanding the extracellular fluid (ECF) levels without interfering with the intracellular fluid (ICF) levels in any major way, and it’s commonly used to correct fluid volume deficits. It can also be used to replenish sodium losses in patients who have experienced severe injuries, like bad trauma or widespread burns. 

However, normal saline solution should never be given to patients with conditions that cause sodium retention, nor should it be given to those with heart failure.

Dextrose 5% in Water (D5W) 

The next example of an isotonic solution is dextrose 5% in water, which is commonly abbreviated to D5W, for easy identification. As the name suggests, this isotonic IV fluid contains dextrose, a form of sugar. 

D5W is quite an interesting IV fluid, as it actually starts off as isotonic but provides free water as the dextrose is metabolized, transforming it into a hypotonic solution over time. This leads to expansion of both the ECF and the ICF. 

Dextrose 5% in water is generally used to balance out any increases in serum osmolality, as well as supplying water to the patient.

It’s important to use this IV fluid with care. It should not be used as a method of fluid resuscitation, as the high levels of sugar in D5W may lead to hyperglycemia in the patient. Not only that, but this fluid should not be administered to patients who are at risk of high cranial pressure, as it could lead to edema.

Lactated Ringers (Ringers Lactate or Hartmann solution)

Next, we have lactated Ringers. This can also be known under various other name variations, like Ringer’s solution, Ringer’s lactate, or even Hartmann solution, but they all refer to the same kind of fluid. 

Lactated Ringers is a type of isotonic IV fluid that is designed to be very similar to the human body’s own natural blend of balanced electrolytes; it contains a mixture of sodium, potassium, calcium, and chloride, as well as bicarbonate precursors, and it doesn’t contain any calories. It’s one of the most versatile and adaptable forms of IV fluid, since it’s so similar to the body’s own blood plasma content. 

Usually, the main use of lactated Ringers is to treat dehydration. It can also replenish sodium levels, and may be used as a treatment for patients with burns, trauma, and other serious injuries. In addition, this is often the fluid of choice when a patient is having fluid resuscitation. 

There aren’t too many risks with Ringer’s lactate, but it relies on the liver, so patients with liver conditions who are unable to metabolize lactate should not be given this particular IV fluid. It also needs to be used carefully in those with heart or renal failure.

2. Hypotonic IV Fluids 

Hypotonic fluids have low levels of solutes and help to draw water into cells. Here are some examples of commonly-used hypotonic IV fluids:

0.225% Sodium Chloride (NaCl 0.225%) 

0.225% sodium chloride solution, which may also be referred to as or 0.225% NaCl, is a type of sodium chloride solution. It’s a lot like regular saline solution in terms of the fact that it contains water, sodium, and chloride, but with a key difference: it contains significantly less sodium chloride.

In fact, compared to standard saline solution, 0.225% sodium chloride solution contains just 25% of the amount of sodium and chloride. 

Typically, this IV fluid is reserved for use in pediatric patients. It’s a good choice of fluid for maintaining fluid levels in young patients, and it’s one of the most hypotonic fluids available at 77 mOsm/L (osmotic concentration level).

0.33% Sodium Chloride (NaCl 0.33%) 

Next, we have 0.33% sodium chloride solution, which may also be referred to as 0.33% NaCl. Again, this is another variety of saline or sodium chloride solution, similar to the likes of normal saline and 0.225% saline, but with a specific 0.33% level of sodium chloride content.

The main use of 0.33% sodium chloride hypotonic IV fluid is to help the patient’s kidneys retain a certain amount of water. It’s also usually used in conjunction with other fluids, like dextrose, to boost tonicity.

Like other kinds of sodium chloride solution, 0.33% sodium chloride needs to be used with care in patients who have heart failure, renal failure, or certain kidney problems.

0.45% Sodium Chloride (NaCl 0.45%) 

Next, we have yet another form of sodium chloride solution. 0.45% sodium chloride, or 0.45% NaCl, may also be known as half normal saline or half-strength saline, is a specific kind of saline solution that has half of the usual levels of sodium chloride compared to standard saline.

It has an osmotic concentration, or osmolality, of 154 mOsm/L and contains equal amounts of sodium and chloride. In terms of usage, this particular fluid is generally used to replace water levels in patients who may be suffering from hypovolemia, hypernatremia, or other conditions. 

Medical personnel must be careful when administering this particular fluid, as too much of it could cause hyponatremia, and it’s not recommended for patients who have a tendency to have water retention, nor should it be given to those with heart or renal failure.

Dextrose 2.5% in Water (D2.5W)

The final example of hypotonic IV fluids in our list is 2.5% dextrose in water, otherwise known among nurses and other medical staff as D2.5W. As the name implies, this fluid contains half of the usual amount of dextrose found in standard D5W solutions.

D2.5W is generally used to treat patients who are dehydrated. It helps to replenish fluid levels, but it should not be used in conjunction with any kind of blood products. If used incorrectly, it could lead to hemolysis.

3. Hypertonic IV Fluids 

Finally, we have hypertonic fluids, which are those that have high concentrations of solutes and help to move fluids out of the cells and into the ECF.

3% sodium chloride (3% NaCl) 

3% sodium chloride, or 3% NaCl, is another example of a sodium chloride solution, but this one is hypertonic. It contains 513 mEq/L of sodium and chloride, which is significantly more than standard saline solution.

The main use of 3% sodium chloride is to replenish sodium levels and treat patients who are suffering from sodium deficiencies. 

In general, this kind of fluid should only be used in extreme circumstances, and it’s vital to infuse 3% NaCl at a very slow and gradual rate. Otherwise, the patient may be at risk of pulmonary edema and fluid overload.

5% sodium chloride (5% NaCl) 

Like 3% sodium chloride, 5% sodium chloride is an example of a hypertonic variant of sodium chloride solution. It may be referred to as 5% NaCl and is one of the highest concentrations of saline solution used in the medical world today.

And just like 3% NaCl, 5% NaCl is used to build up sodium levels in patients who may be suffering from a severe lack of sodium.

There are very high risks of pulmonary edema and other unwanted side effects when working with such a highly concentrated version of sodium chloride solution, so 5% NaCl should only be administered at a very low flow rate and the patient should be monitored for any problems.

Dextrose 10% in Water (D10W) 

There are also various hypertonic dextrose solutions that may be used for IV therapy. Dextrose 10% in water, or D10W, is one of the most commonly-used examples. 

This solution contains twice as much dextrose as D5W, and it’s used for treating ketosis, as well as providing free water and some calories. 

Like other hypertonic dextrose solutions, D10W actually transforms to an isotonic solution quite quickly, as the body metabolizes the dextrose, leaving only the isotonic solution behind. 

When working with D10W, it’s important to use a central line, if possible, as smaller veins may be at a higher risk of issues like extravasation.

Dextrose 20% in Water (D20W) 

Dextrose 20% in water, or D20W, is another example of a hypertonic dextrose solution. It has twice as high concentration levels of dextrose when compared to D10W and it’s used to promote diuresis.

Dextrose 50% in Water (D50W)

Finally, there’s dextrose 50% in water, or D50W, which has a very high level of dextrose. It’s used to treat patients who are suffering from extremely low levels of blood sugar, or hypoglycemia, and it has to be administered via an IV bolus.

What Are Colloid IV Fluids? 

Other forms of IV fluids that you might have to work with in a medical setting include colloid fluids. But what are colloid fluids? Well, a colloid is a particularly big molecule that won’t pass through semipermeable membranes in the same way that smaller molecules do. So, a colloid fluid is a type of IV fluid that has solutes with big molecules. 

In terms of whether they are isotonic, hypotonic, or hypertonic, colloid fluids technically fall into the hypertonic category, as they pull fluids out of extracellular spaces. They’re useful for widening the volume of the intravascular space, as well as increasing blood pressure

In general, colloid fluids should be given to patients who are starving or malnourished, and they’re also recommended for patients whose bodies are not very tolerant when it comes to taking in lots of fluid.

What Are the Different Types of Colloid IV Fluids?

There are several different examples of colloid IV fluids, including:

• Human Albumin – Human albumin is a colloid fluid made from genuine human plasma. It’s available in two varieties: 5% and 25%. 5% is usually used to boost the circulating volume and replenish proteins after injuries like trauma and burns. 25%, meanwhile, is usually used to treat edema.
• Dextrans – Dextrans are common carbohydrates that are available in two forms: low-weight and high-weight. They can also be available in both saline or glucose fluids and have a range of uses. Low-weight dextrans are helpful for treating shock, while high-weight dextrans are good for patients who are suffering from hypovolemia.
• Etherified Starch – Etherified starch is another example of a colloid fluid used for IV therapy. Made from starch, this fluid is used to boost the levels of intravascular fluid, and some common varieties include Voluven and Hyper HAES.
• Plasma Protein Fraction – Plasma protein fraction, or PPF, is another fluid that is made from plasma. It has to be heated before it is used and can be helpful for boosting the circulating volume.

Where Can I Buy IV Solutions in Prefilled Infusion Bags?

If you’re interested in ordering IV solutions like Ringer’s lactate and saline in prefilled infusion bags, ready to be used, choose CIA Medical. We have a wide range of prefilled infusion bags in various types and sizes, from trusted medical brands.