Topic summary

Reading U-100 graduations, with a conversion table

Devices › Syringes & needles dead volume worked example subcutaneous injection needle gauge & length

This is a generated summary. It shows the 6 most-liked posts from a topic of 42, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.

k.fonsecaTL2 Moderator15 Dec 2025#3

y.eriksen, post #1: Posting this under the heading it deserves: Reading U-100 graduations, with a conversion table Everything below is what sits behind that. Practical question with the units stated, because I have seen how quickly these go wrong without them. I have a 5 mg vial of tirzepatide and I am working to a 0.5 mg step. My syringes are U-100… Go to post

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

23 likes in reply to #1 7mo

r.aldana_pharmdTL4Pharmacist23 Jan 2026#8

Dead volume: residual liquid in the hub and needle after withdrawal. Typical residual is 0.01 to 0.02 mL for an insulin syringe with a fixed needle. Accounting for it matters if precision matters.

32 likes 6mo

v.bhattacharyaTL2 Moderator18 Feb 2026#12

Picking up post #9: that is the part I would want checked first.

Fixed versus detachable needles: insulin syringes usually have fixed needles (no dead volume loss to the hub). Luer-lock syringes use detachable needles (more dead volume). Fixed needles are preferred for small doses.

21 likes 5mo

f.amankwahTL2 Moderator8 Mar 2026 · edited#15

bench_notes, post #6: Worth separating two things that post #2 runs together. Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive. Go to post

Needle length: typical lengths for subcutaneous injection are 4-6 mm (short), 8 mm (standard), or 10-12 mm (longer). Longer needles are needed for deeper tissue or if you have abdominal adiposity.

30 likes in reply to #6 5mo

journalclub_wrenTL3Regular9 May 2026#26

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

27 likes 3mo

diluent_watchTL2Member18 Jun 2026#34

Picking up post #31: that is the part I would want checked first.

Aspirating before injection: for subcutaneous injection, aspirating (pulling back on the plunger to check for blood) is not necessary and is sometimes discouraged because it is associated with more discomfort. Subcutaneous injection without aspiration is standard practice.

25 likes 1mo

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A ten-fold dose error caught before injection — one year onDevices › Syringes & needles · 157 replies

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