Identifying Isotonic, Hypertonic, & Hypotonic Solutions Pt 2

Hello guys.

Mike’s back for part 2 of your IV solutions namely: isotonic, hypertonic, and hypotonic. At, we turn your frown upside down by filtering all those unnecessary details and focusing on the ones that matter… the ones that will definitely show up on your exams.

A brief recap

In part 1, we’ve discussed how to easily identify your intravenous solutions. You can do it by remembering the following:

  1. Hypotonic fluids are hippotonic cells because all the fluid goes into the cell causing it to swell.
  2. Hypertonic fluids are for skinny cells because the fluid goes out of the cell, making it skinny. When people are hyper, they become skinny.
  3. Isotonic fluids are isoperfect cells, like “I’m so perfect.” This means that there’s no osmosis or shifting is happening with the cell.

Now that we were able to refresh your memory, the next thing that you have to keep in mind is how to pinpoint an IV solution once you have spotted one.

IV Solution Numbers

Mike got this wrong on his test and because of his frustration, he committed himself to finding a simpler way to remember these IV solutions. Mind you, it will come out of your test and when it does, it will be very difficult if you didn’t know how to find your way around it.

There are a couple of different types of IV solutions created based on how they’re used. Sometimes, remembering all these numbers can be quite overwhelming because they are confusing. How do you do it?

  1. Hypotonic – all the fluid rushes into the cell. What do hypotonic solutions consist of?
  • ½ Normal Saline (0.45%)
  • ¼ Normal Saline (0.225%)
  • 1/3 Normal Saline (0.33%)

Remember: Anything above 0.30% Normal Saline is considered as a hypotonic solution.

  1. Hypertonic – all the fluid rushes out of the cell. What do hypertonic solutions consist of?
  • 3% Normal Saline
  • 5% Normal Saline
  • D10W
  • D5W

Remember: Numbers that don’t go beyond 30% are considered as hypertonic solutions. People who are hyper are skinny, therefore, their numbers are limited to a single digit and can go as far as double digits but not over 30%. Those solutions that have Ws labeled on them is a hypertonic solution.

  1. Isotonic – isoperfect, nothing is happening inside and outside the cell. Osmosis is not present.
  • Normal Saline
  • NS 0.09
  • Sodium Chloride (NaCl)

Remember: Blood has the same consistency as isotonic solutions. Therefore, during post-op surgeries, Lactated Ringer’s solution is given.

One for the books

Nursing tests love inserting questions about isotonic solutions primarily because it is one of the most commonly used solutions in a hospital setting. They will keep on adding those questions in your exams until you get it right because isotonic solutions are integral in healthcare.

A scenario that usually gets placed in exams is the one wherein a client is hypovolemic, having low blood volume inside the body. What solution should you use? So first, you need to consider these:

  1. Hypovolemic clients require fluid within the intravascular space
  2. Hypovolemic clients require fluid to fill their veins
  3. Fluid is not necessary inside the cells
  4. Fluids do not come out from the cells
  5. You need something just right

Answer: Isotonic. Because you just want things to be perfect (isoperfect).

Memorize this by heart. And hopefully, when you encounter IV solution questions in your exams, you can efficiently identify what specific solution to use.

You can check out other lectures on a wide variety of nursing topics on our website, and at our YouTube channel.

Until next time!

Identifying Isotonic, Hypertonic, & Hypotonic Solutions Pt 1

Let’s face it, intravenous (IV) solutions, are burdensome to remember.  It’s confusing! It gets even more complicated if it shows up during your examination. How are you going to differentiate one fluid from another? If you are not familiar with the concepts of each IV solution, chances are, you’ll flunk your exam.

If only there’s just an easier way to remember the indications and mechanism of action for all three, it’ll definitely save you from hours of tedious memorization.

Fortunately, at, Mike has formulated the easiest, most amusing way to correctly identify your hypotonic, isotonic, and hypertonic solutions.

Mike’s fun study tip

When memorizing something that can be a bit confounding, it would be so much easier to connect the complicated physiology to an image that’s closely related to it.

Here’s how…

Hypotonic is for Hippo

In cases of dehydration or medication treatments, the hypotonic solution is the IV solution of choice. This is because hypotonic solutions contain fewer electrolytes and sodium. Oftentimes used if there is decreased solute level outside the cell and the goal is to shift that back inside through osmosis in order to put everything back to normal.

Now, to be able to remember that, think of hypotonic fluids as a hippo. Got it? Hypo to hippo. Why? When fluid goes into your cell, it causes the cell to become full and swollen, like a hippo.

Uses: Hyperosmolar hyperglycemia, diabetic ketoacidosis (DKA)

Hypertonic is for Skinny

On the other hand, hypertonic solutions are used when solutes are increased extracellularly. Osmosis causes water to run from inside out. If this happens, the cell will shrink.

With hypertonic solutions, the first thing that you have to think of is what would happen to someone who is hyper? They have a lot of energy that makes them do activities like running around, keeping them fit and skinny. Hypertonic solutions cause the cell to become skinny because of the fluid that escapes from it.  As Mike puts it, hypertonic is to running and running is to skinny.

Uses: Most likely given to counter the effects of fluid overload or pulmonary edema

Isotonic is for I-so-perfect

Intravascularly, isotonic solutions don’t cause osmotic shifting from the cell to the vascular spaces. There is an equal concentration of cellular conditions.

This can be remembered by simply putting it this way – isotonic is Isoperfect. And being perfect means you don’t have to change anything, you are not required to gain or lose, everything is perfect – Isoperfect.

Uses: Dehydration, surgery

As a recap, here are the things that you need to keep in mind:

  1. Hypo is to hippo. Hippo is to swollen cells.
  2. Hyper is to Skinny. Skinny is to emaciated cells.
  3. Isotonic is to Isoperfect. Isoperfect is to no exchange of fluids required.

By remembering these, you are now able to get the questions related to IV solutions in your next nursing exam. Hopefully, this was able help clear concepts that seem jumbled up for you.

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