Contents
>Calculating injection values with concentration, volume, and dose
>Reading U100 and U40 syringes
> Subcutaneous
> Intramuscular
Intro
I am going to preface this by saying that I have zero professional experience on this topic (not reassuring, I know, but this is something you should be aware of). This document is simply a bunch of information compiled into bite sized pieces with self-injecting transgender individuals kept in mind.
This document contains a lot of information on needles, how to inject, and hormone dosing. If you are going to use the information in this doc, remember that I am not a professional.
Needles
Needles are classified by three main factors: length, gauge (thickness/girth of the needle) and syringe volume. A higher gauge number means a slimmer needle, eg:- a 31g needle is slimmer than a 25g needle. The volume of the syringe is determined by its capacity. (Galan)
Injection types for hormone therapy
Injection types are defined by their depth and location. For the sake of this document I will stick with injections for hormones.
For hormones, there are two types of injections: subcutaneous (SubQ or SubC) and intramuscular (IM).
Subcutaneous
A subcutaneous injection is an injection administered to the fat layer of the skin, below the dermis. Injections to the fat absorb slower than intramuscular injections (Kim). Subcutaneous injections are generally considered less painful due to slimmer needle gauges and shorter needles. The subcutaneous layer is also called the hypodermis.
Intramuscular
Intramuscular injections are administered directly to the muscle, which is below the subcutaneous layer. They use longer needles with a thicker gauge. (Varma and Chastain)
Needle choices
The volume of a hormone injection is typically small (0.1~0.5 ml), hence 1 ml syringes are preferable. The needle gauge and length depends on whether you are doing IM or SubQ. As a general rule, IM injections have longer needles and lower gauges than SubQ needles.
Subcutaneous needles are typically ½ to ⅝ inches (12.7 to 15.875 mm) long with gauges ranging from 25 to 30.
Intramuscular needles are typically 1 to 1.5 inches (25.4 to 38.1 mm) long with gauges ranging from 20 to 22. (Galan)
Calculating dosages
Calculating injection values with concentration, volume, and dose
The amount of medicine you will inject will be defined in terms of dose (usually measured in milligrams (mg)). Concentration of medicine varies between vials, and the volume of medicine you should inject depends on the concentration and dose. Dose is the only thing that remains absolute in your regimen, so that is the value you should focus on.
Concentration means the dose of medicine per unit volume of solution. So a vial labeled 40mg/ml would have 40 mg of medicine in 1 ml of solution, 20 mg of medicine in 0.5 ml of solution, and so on.
Do not describe your regimen in terms of volume. “I take 0.2 ml of medicine weekly” does not mean anything; the dose in 0.2 ml of solution would differ depending on concentration. “I take 6 mg of medicine weekly” actually indicates the strength of your dose.
So, hypothetically, if somebody has decided to take 6 mg of estrogen weekly, and they have a 40 mg/ml vial, they would inject 0.15 ml of the medicine from the vial weekly (6/40 = 3/20 = 0.15)
Make sure you are using correct units when calculating. For example, do not calculate using a dose measured in micrograms with a concentration measured in mg/ml. This will give you wildly inaccurate values. Convert the values to the correct unit before calculation. In this example you would convert the micrograms to milligrams.
Reading U100 and U40 insulin syringes
A good amount of transgender people use insulin syringes to administer hormones. However, the demarcations on insulin needles are done in terms of “units” rather than ml, which may confuse some.
For a U100 syringe, each demarcation (unit) is equal to 0.01 ml. So for a 0.1 ml dose, you would draw the plunger up till the 10th demarcation on the syringe. (“How to Read an Insulin Syringe”)
For a U40 syringe, each demarcation is equal to 0.025 ml. So for a 0.1 ml dose, you would draw the plunger up till the 4th demarcation on the syringe. (Cariño)
U40 syringes are uncommon and have been largely phased out in favor of U100 syringes, but I am adding this section to prevent confusion and misdosing.
Injection sites
Before injecting, you need to decide where you will be injecting. Here are the spots typically used for each type of injection:
Subcutaneous: stomach, thigh or arm. (Radhakrishnan)
Intramuscular: Deltoid muscle (upper arm), Vastus lateralis muscle (outer thigh), Ventrogluteal muscle (hip), and Dorsogluteal muscle (butt). (Martin)
Arm sites are usually avoided due to difficulty in self injecting there.
Picking between subcutaneous and intramuscular
Most injectable hormones can be administered by both SubQ and IM injection. This may leave some people at odds as to whether to inject SubQ or IM. This section will discuss the pros and cons of each injection.
The main thing people may be concerned about would be efficiency. As stated earlier, Subcutaneous injections are absorbed slower than intramuscular due to a lower number of blood vessels in the layer, which may lead you to think that SubQ injections lead to lower levels. However, There is no significant difference in hormone levels between SubQ and IM injections. (“Comparison of the Subcutaneous and Intramuscular Estradiol Regimens as Part of Gender-Affirming Hormone Therapy”)
Subcutaneous injections are absorbed slower by the body, leading to stabler levels compared to intramuscular injections. IM injections lead to sharper “peaks” in hormone levels due to faster absorption by the body. (VanSickle)
There is a psychological barrier when it comes to IM injections. People will, obviously, be more afraid of IM injections because of the longer, thicker needle. IM injections generally are considered more painful than SubQ. (Weatherspoon and Villines)
Subcutaneous injections can cause rashes, itchiness and redness at the site post-injection. Intramuscular injections also leave injection site pain but are less prone to causing itchiness and irritation. (“Medication Routes of Administration - StatPearls”)
Leakage tends to reduce with longer needles. However, in a study done on needles of length in the range 4.5mm to 12mm, injections showed minimal variation in leakage (0.59% to 0.38% of injected medicine). (Wittmann)
Aspiration
Aspiration is the drawing-back of the syringe plunger to check if the needle has been inserted into a blood vessel. To aspirate, the plunger should be pulled up for up to 10 seconds to wait for signs of blood. If blood enters the syringe, the syringe should be discarded and a new dose should be prepared. Do not attempt to inject anyways. (“How to Aspirate a Needle Before an Injection (And Why It’s Done)”)
Aspiration is generally considered unnecessary for SubQ injections. (“Administering Subcutaneous Injections”)
Please do your own research on whether or not to aspirate for IM injections, as I don't think the source for the following paragraph is completely reliable, and I could not find better sources.
For IM injections, aspiration is considered unnecessary except for injections to the Dorsogluteal site. (“Do you need to aspirate when giving intramuscular (IM) injections?”)
Administering injections
Ok, now onto the scariest part of this process: actually injecting.
I advise you to not follow through with these steps before finishing the entire document. You can follow these steps after you’ve already read them and the rest of the document at least once. I found it more comfortable to inject the first time while rewatching a youtube guide.
Here is a list of supplies you will need. Keep them all together before starting. This will make it a lot less stressful for you, and also reduces the amount of time the needle spends exposed to air.
I highly recommend the channel living with XXY. It has a lot of very good self injection videos
Subcutaneous
Stomach injection: Subcutaneous Injection Training - Injecting the Medication
Thigh injection: Giving Yourself Subcutaneous Hormone Shots
Intramuscular
Quadriceps injections: Ququadricep Intramuscular Testosterone Injection
Gluteal injection: One Handed Testosterone Gluteal Injection
Locating Vastus lateralis: Locating vastus lateralis
Loss of volume
During injection, some of the hormones may be lost due to two things: leakage and dead space.
Leakage
Slightly more prevalent in subcutaneous injections, leakage refers to the loss of medicine through it leaking -hence the name- out of the hole through which the needle entered the skin.
Usually though, leakage causes a negligible loss in hormones, even if it appears to be a large amount. Leakage is less in stomach SubQ injections than in thigh SubQ injections.
Leakage tends to be inevitable, however it can be minimized through techniques discussed in the section injection techniques. (Præstmark)
Dead space
Almost all syringes have dead space. Dead space refers to the space left between the plunger and the needle after the plunger has been fully pushed in, where medicine may remain and not leave the syringe after delivery. A portion remains in the needle itself as well.This medicine has been wasted. Dead space can be minimized through techniques discussed in the section injection techniques. (Lee and Challa)
Your responsibility
DO NOT REUSE NEEDLES. Thank you.
As someone who uses needles, you have the responsibility to keep other people’s safety in mind. Do NOT break needles, do NOT bend needles, and always follow disposal regulations. Look up your local needle disposal laws before getting rid of them.
Needlestick injuries can cause HIV. Sure, you might know that you don't have HIV, but the poor garbage disposal person who stuck themselves on your incorrectly-disposed needle won't. Either they’ll have to spend a bunch of money on a disease test, or if they're broke, they will have to spend their life being crushed by the fear that they might have a deadly disease.
Put your needles in a sharps container after use. After the container is filled, you can give it to a pharmacy, hospital or biohazardous waste disposal company. (“DOs and DON'Ts of Proper Sharps Disposal”) (“Best Way to Get Rid of Used Needles and Other Sharps”)
If you absolutely cannot access a sharps container, at least store your used needles in any thick plastic container and label it as containing sharps; for example, you could use empty shampoo bottles. [This paragraph of advice is purely harm reduction. It will always be preferable to use a proper sharps container]
Injection techniques
This section will address techniques used to minimize medicine loss due to leakage and needle dead space.
Z-tracking
This is a technique used to minimize leakage for IM injections, though it also has some effect when used for SubQ injections.
Z-tracking involves pulling the skin to the side before injection and then letting go of it after removing the needle. Releasing the skin seals the medicine by displacement of the skin, fat and muscle. (Vallie)
Here are some videos:
Subcutaneous Injections: Z-Track Method ~ivyVILOs~(Ivy Tech Community College, School of Nursing)
Intramuscular Z-track Injection
Z track IM injection skills training
Air-locking
Air locking is used to minimize leakage and needle dead space.
Air locking involves drawing 0.1 to 0.2 ml of air into the needle along with the medication before injection. The entire contents of the syringe are then injected. The extra air in the syringe pushes out any medicine occupying the dead space, taking its place. The injected air also creates a sort of “lock” over the injected medication, preventing it from leaking. (Jannak)
Normal method (left) VS Airlocking (right). The air replaces medicine that would be otherwise wasted. Image has exaggerated proportions to facilitate better understanding of how the method works.
About the fear of injecting air:
“An injected air bubble can go through your bloodstream and into your heart and kill you” is probably something you’ve seen in a medical drama. These are called air embolisms, and they are caused by air being injected intravenously. Hormone injections are done into tissue, not blood vessels.
Up to 50 ml of blood-vessel-injected air is generally considered safe. With air locking you are injecting less than 0.2 ml of air, and it's not even into a blood vessel in the first place. (Westreich)
Please do seek your own sources as well if you are still nervous about attempting to air lock.
Estradiol esters dosage information
IMPORTANT NOTE: All dosage values given here are directly copied from the wikis- DIY HRT Directory and HRT Cafe. I could not find any other *reliable* sources, and the wikis themselves state that they do not provide professional advice. Please keep this in mind when looking at the dosage values.
Dosage simulators: Injectable Estradiol Simulator Advanced - Transfeminine Science
Injectable Estradiol Simulator 2.0
[Dosages listed here are for the esters in injection form]
MTF HRT by injection is usually done by monotherapy. This means that only estrogen is injected, no testosterone suppressor. This is because injected estrogen is usually enough to suppress testosterone on its own.
All dosages listed here assume monotherapy.
There are four main injectable estradiol esters for HRT:
(Index Nominum 2000: International Drug Directory #)
Dosages given by diyhrt.wiki:
Estradiol Valerate (EV): 4 mg every 5 days
Estradiol Cypionate (EC): 5 mg every 7 days
Estradiol Enanthate (EEn): 7 mg every 10 days
Dosages given by hrtcafe.net:
Estradiol Valerate: 3-6 mg every 5 days or less
Estradiol Cypionate: 4-8 mg around every 7 days
Estradiol Enanthate: 4-8 mg around every 7 days
Estradiol Enanthate: 6-10 mg around every 10 days
Estradiol Undecylate (MCT Oil): 15-25 mg around every 21 days
Estradiol Undecylate (Castor Oil): 40-60 mg around every 31 days
Testosterone esters and dosage information
IMPORTANT NOTE: All dosage values given here are directly copied from the wikis- DIY HRT Directory and HRT Cafe. I could not find any other sources, and the wikis themselves state that they do not provide professional advice. Please keep this in mind when looking at the dosage values.
Injectable testosterone has three main esters:
Dosages given by diyhrt.wiki:
Note that the ranges given are very large. Please seek several alternative sources when deciding your dosages. I must remind you again that these dosages are direct excerpts from the wiki.
Testosterone Enanthate and Cypionate have very similar half lives.
Testosterone cypionate: 20 or 50 or 100 mg/week.
Testosterone enanthate: 20 or 50 or 100 mg/week.
Do not use these dosages without your own research first.
Bibliography
Works Cited
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“Best Way to Get Rid of Used Needles and Other Sharps.” FDA, 10 August 2023, https://www.fda.gov/medical-devices/safely-using-sharps-needles-and-syringes-home-work-and-travel/best-way-get-rid-used-needles-and-other-sharps. Accessed 7 November 2024.
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“Comparison of the Subcutaneous and Intramuscular Estradiol Regimens as Part of Gender-Affirming Hormone Therapy.” Endocrine Practice, 28 February 2023, https://www.endocrinepractice.org/article/S1530-891X(23)00050-2/abstract. Accessed 8 November 2024.
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Index Nominum 2000: International Drug Directory. Medpharm Scientific Publishers, 2000.
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