mg vs mcg vs units, can someone explain like im 5?

UnitConfusionSenior Analyst

ok i get that 1mg = 1000mcg. what i dont get is units.

people say "10 units" like its a dose but 10 units of what? the syringe says units, the vial says mg, and nobody explains how they connect. i tried to work it out from a few posts and got three different answers.

is units a mass thing or a volume thing? and if its volume then how does anyone know what theyre actually drawing up

15 replies16 upvotesBeginner Questions

15 replies

  • decimal_placesSenior Analyst

    Volume. On a U-100 insulin syringe 100 units = 1 ml, so 1 unit = 0.01 ml. That's it, that's all the syringe knows.

    What's in that 0.01 ml depends entirely on how much water went into the vial. 10mg in 2ml is 5mg/ml, so 10 units = 0.1ml = 0.5mg. Same vial with 1ml is 10mg/ml and 10 units = 1mg. Same mark, double the amount.

    18 upvotes

  • UnitConverterSenior Analyst

    And not every syringe is U-100. U-40 exists and the marks mean something different. Three unknowns is enough to get any answer you want, which is why you got three answers.

    11 upvotes

    • UnitConfusionSenior Analyst

      i did not know U-40 was a thing. thats kind of alarming given how casually people throw unit numbers around

      5 upvotes

  • deload_weekAnalyst

    this is the post i needed 6 months ago

    5 upvotes

  • cold_chainSenior Analyst

    Should be pinned. Comes up weekly.

    6 upvotes

  • quick_qSenior Analyst

    u100 is the normal insulin one right?

    2 upvotes

  • newvialwhodisSenior Analyst

    genuinely thought units were a mass thing until right now

    5 upvotes

  • same_tbhSenior Analyst

    same and ive been reading for months

    3 upvotes

  • newvialwhodisSenior Analyst

    is u40 common?

    1 upvote

  • quick_qSenior Analyst

    so why do people say units at all if it means nothing?

    2 upvotes

    • UnitConverterSenior Analyst

      Because it's what's printed on the syringe so it's what you read off. Means something to the person holding it, means nothing to anyone else unless they also say the concentration.

      7 upvotes

    • quick_qSenior Analyst

      ok that makes sense

      2 upvotes

  • LibraryLurkerSenior Analyst

    bookmarked

    1 upvote

  • welcome_wagonSenior Analyst

    This is the kind of question people are embarrassed to ask, which is exactly why it should stay visible.

    4 upvotes

  • first_vialSenior Analyst

    saving this one

    2 upvotes

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