# What is the purpose of saline in the IV solution given a person suffering acute hypoglycemia? **URL:** \ **Category:** Factual Questions\ **Created:** [December 13, 2011, 11:36pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104 "2011-12-13T23:36:42Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [December 13, 2011, 11:36pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/1 "2011-12-13T23:36:42Z")
A person who is suffering acute hypoglycemia and is unable to receive oral glucose gel or tablets is treated by being given an IV solution containing dextrose and saline. What is the purpose of the saline? Is it just a medium for the dextrose, or is there some other purpose? ---
**Author:** ![Corresponder](https://avatars.discourse-cdn.com/v4/letter/c/22d042/32.png) [@Corresponder](https://boards.straightdope.com/u/Corresponder)\ **Post date:** [December 14, 2011, 12:04am UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/2 "2011-12-14T00:04:42Z")
As far as I know, the solution given in an emergency case of hypoglycemia is 50cc of 50% dextrose in water. I don’t believe there is any sodium chloride in it. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [December 14, 2011, 12:48am UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/3 "2011-12-14T00:48:16Z")
You always want an IV to have the same concentration: Too much solutes in the water, and water will flow from your tissues into your blood vessels to equalize the concentration, and too little, and it’ll flow the other way, into the tissues. So I imagine that if the medically-indicated amount of sugar isn’t enough, they make up the rest of the solutes with salt. ---
**Author:** ![Shmendrik](https://avatars.discourse-cdn.com/v4/letter/s/ee7513/32.png) [@Shmendrik](https://boards.straightdope.com/u/Shmendrik)\ **Post date:** [December 14, 2011, 12:58am UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/4 "2011-12-14T00:58:33Z")
The saline is to ensure that you are not getting hypotonic fluid. ---
**Author:** ![XRaeth](https://avatars.discourse-cdn.com/v4/letter/x/f14d63/32.png) [@XRaeth](https://boards.straightdope.com/u/XRaeth)\ **Post date:** [December 14, 2011, 1:38am UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/5 "2011-12-14T01:38:55Z")
If I recall correctly from high school biology, the saline is present in the IV solution so that it has the same concentration of solutes as your blood cells. If you were to use an IV without saline, there would be a lower solute concentration outside of your blood cells (and higher inside) so water would rush into the blood cells in order to try and equalize the concentration of solutes. The water moves because it can move through the membrane of the cell much easier than the solute can. This sudden influx of water can actually cause the cell to burst, which can be potentially dangerous. My memory might not be perfectly correct, but I think that’s the gist of it. As to why the dextrose doesn’t count towards the solute concentration, I’m not sure. I suspect it’s either because the concentration of the dextrose isn’t high enough to fully balance with your cells and the saline takes care of the remainder, or the movement of water can depend on individual solute concentrations and the saline overpowers the dextrose. I’m probably wrong about that though. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [December 14, 2011, 3:08pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/6 "2011-12-14T15:08:04Z")
> [@Shmendrik](#): > > The saline is to ensure that you are not getting hypotonic fluid. It’s sweet that you think I might know what _hypotonic fluid_ means or why it’s a bad thing. ---
**Author:** ![Spatial\_Rift\_47](https://avatars.discourse-cdn.com/v4/letter/s/a8b319/32.png) [@Spatial\_Rift\_47](https://boards.straightdope.com/u/Spatial_Rift_47)\ **Post date:** [December 14, 2011, 4:21pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/7 "2011-12-14T16:21:58Z")
**Skald** , an explanation of tonicity can be found (where else?) on the wiki page: [Tonicity - Wikipedia](http://en.wikipedia.org/wiki/Tonicity) But in particular, a hypotonic fluid is one with less concentration of solutes (like NaCl) compared to the interior of the cell. Too much fluid is then drawn into the cell, and the cells may start to burst. This would be bad. So in giving a hypoglycemic patient a solution with dextrose and salt, they are making sure the cells don’t overdo it when drawing in the sugar water. ---
**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\ **Post date:** [December 14, 2011, 4:27pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/8 "2011-12-14T16:27:06Z")
The initial treatment would be a rapid dose of 50% dextrose (D50) followed by an infusion of D5 1/2NS (which is a 5% dextrose solution in 0.5 normal saline), this is approximately an isotonic fluid. ---
**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\ **Post date:** [December 14, 2011, 5:45pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/9 "2011-12-14T17:45:08Z")
As others have said, the solution has about the same amount of salt as blood plasma. Delivering an IV that doesn’t have salt would be much like pouring a bunch of distilled water into a saltwater aquarium. It’s bad for the patient for the same reasons that it would be bad for the fish. ---
**Author:** ![Skald\_the\_Rhymer](https://avatars.discourse-cdn.com/v4/letter/s/ecccb3/32.png) [@Skald\_the\_Rhymer](https://boards.straightdope.com/u/Skald_the_Rhymer)\ **Post date:** [December 14, 2011, 5:55pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/10 "2011-12-14T17:55:02Z")
Thanks to all who responded. ---
**Author:** ![USCDiver](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/uscdiver/32/354_2.png) [@USCDiver](https://boards.straightdope.com/u/USCDiver)\ **Post date:** [December 14, 2011, 9:17pm UTC](https://boards.straightdope.com/t/what-is-the-purpose-of-saline-in-the-iv-solution-given-a-person-suffering-acute-hypoglycemia/606104/11 "2011-12-14T21:17:27Z")
> [@cornflakes](#): > > As others have said, the solution has about the same amount of salt as blood plasma. Delivering an IV that doesn’t have salt would be much like pouring a bunch of distilled water into a saltwater aquarium. It’s bad for the patient for the same reasons that it would be bad for the fish. This is true in the general sense, but as with all things medical there are exceptions. Some diseases require either more concentrated or more dilute IV solutions to be used.