How syringe units work for peptide dosing
Syringe units are a volume scale. They help you read a syringe, but they do not describe a peptide dose until the vial concentration is known.
Key takeaways
- U-100 means 100 units per 1 mL.
- A unit marking is not a dose by itself.
- Changing concentration changes what each unit contains.
How to read syringe markings
Source: RegisteredNurseRN
Video notes
- Syringe markings are read as volume markings, not peptide amount.
- Insulin syringes use unit markings, while other syringes may use mL markings.
- For peptide calculations, the syringe reading only becomes a dose after concentration is known.
What U-100 means
A U-100 insulin syringe is marked so that 100 units equals 1 mL. That means 10 units equals 0.1 mL and 50 units equals 0.5 mL.
The peptide amount inside that volume depends entirely on concentration.
Common unit-to-mL examples
For U-100 syringes, the unit number is directly tied to hundredths of a mL. That makes common conversions easy to audit before calculating peptide mass.
- 5 U-100 units = 0.05 mL
- 10 U-100 units = 0.1 mL
- 25 U-100 units = 0.25 mL
- 50 U-100 units = 0.5 mL
50 units to mg needs concentration
A 50-unit mark on a U-100 syringe is 0.5 mL. The peptide amount inside that 0.5 mL changes with concentration.
For example, 0.5 mL from a 2.5 mg/mL vial contains 1.25 mg. The same 0.5 mL from a 5 mg/mL vial contains 2.5 mg.
Why concentration matters
If a vial is more concentrated, each unit contains more peptide. If a vial is more diluted, each unit contains less peptide.
This is why two people can draw the same number of units and still be taking different amounts if their vial setups differ.
When to change syringe settings
Change the syringe type in the calculator if you are not using a U-100 syringe. The mL draw can be the same while the unit marking changes.