Devices · Syringes & needles

Reading U-100 graduations, with a conversion table — what changed since

Devices › Syringes & needles worked example dead volume syringe units subcutaneous injection

m.brobergTL2 Moderator25 Jul 2025#1

Reading U-100 graduations, with a conversion table — what changed since Writing it up because I had to work it out twice and would rather nobody else did.

Practical question with the units stated, because I have seen how quickly these go wrong without them.

I have a 2 mg vial of semaglutide and I am working to a 2.5 mg step. My syringes are U-100 insulin syringes, 1.0 mL barrel.

I can do the arithmetic and I have done it twice, getting the same answer both times, but I would like someone to check the reasoning rather than the number — specifically whether I have thought about the residual volume correctly, and whether the graduation I am landing on is one a person can actually read.

1 like 12mo

p.ostergaardTL2 Moderator16 Jan 2026#2

Sharps disposal: needles and syringes should be disposed in a sharps container (a rigid, puncture-resistant container). Do not put them in regular trash. Many pharmacies accept filled sharps containers.

0 likes 6mo

c.okaforTL3Regular23 May 2026#3

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.

13 likes 2mo

This topic was referenced in

Filter needles: when they help and what they cost youDevices › Syringes & needles · 50 replies

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