This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.
A site rotation scheme that actually works: abdomen, outer thigh, back of arm, outer hip. Rotate through them in order, move a minimum 2 cm between consecutive sites, note the site with each dose. If a local reaction appears you have the history. If you rotate properly you will not get lipohypertrophy from overuse of one area.
Adding this to the thread rather than to the wiki, because I am not confident enough for the wiki.
Leak-back after withdrawal: a small amount of liquid on the skin after withdrawal is ordinary. Whether you lost a "meaningful" dose depends on concentration and your target dose, but some leak-back is universal and does not need to be treated as an error.
The step people skip is the one I have spelled out.
Summarising the partial dose because the pen thread so far, since it is long and the answer is buried: the first reply has the method, the fourth has the correction to it, and the rest is people agreeing at length.
Where I part company with post #65, and it is a narrow parting.
The failure mode on partial dose because the pen is boring rather than dramatic. It is almost always the step everyone assumes was done correctly because it is too simple to get wrong.
I read post #65 twice before replying, because I had assumed the opposite.
A site rotation scheme that actually works: abdomen, outer thigh, back of arm, outer hip. Rotate through them in order, move a minimum 2 cm between consecutive sites, note the site with each dose. If a local reaction appears you have the history. If you rotate properly you will not get lipohypertrophy from overuse of one area.
A methods point on partial dose because the pen rather than a substantive one: if the comparison is not like for like, the difference you are measuring is the difference in method.
Note the site alongside the dose. If a local reaction appears three weeks later you will want to know where the previous four injections went.
The reasoning is more useful than the number, which is why I have shown it.
A definition problem is doing most of the work in this partial dose because the pen discussion. Once the term is pinned down I suspect the disagreement mostly goes away and what is left is small.
Post #70 and I disagree about the size of the effect, not about the direction.
Practical experience of partial dose because the pen, offered as one case with the conditions stated, not as a general finding. Conditions first, because they are what make it interpretable.
A genuinely late dose: the labelling generally says that if the next dose is more than a couple of days away, take it as soon as you notice. If the next dose is close, skip it and resume the schedule. The reasoning follows from the long half-life; you are perturbing a slowly moving average.
Where I would look next, rather than where I would stop.
What I would check first on partial dose because the pen is whether the thing being measured moved or whether the way of measuring it moved. Those look identical in a graph.
I had written a reply contradicting post #78 and deleted it. Here is what survived.
The claim about partial dose because the pen upthread is stronger than its source supports. I have read the source. The source says "associated with" and the post says "causes".
Worth separating two things that post #79 runs together.
Leaving the needle in for a couple of seconds after depressing the plunger reduces leakage at the site. It costs nothing and it is the fix for the "some came back out" question.
Not a conclusion. A place to stand while looking for one.
The number people quote for partial dose because the pen is a central estimate presented without its interval, and the interval is wide enough that the estimate is nearly uninformative on its own.
Post #83 answers the question as asked. The question underneath it is different.
The single most common technique error described here is drawing to the wrong graduation because the barrel was read at an angle. Read it straight on, at eye level, every time.
If anyone has run this properly I would rather read that than my own guess.
Whatever the answer on partial dose because the pen turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, invite the correction.
On partial dose because the pen, I would rather understate and be corrected upward than overstate and be quoted. That is a house style here and it is a good one.
Coming back to post #83, because the follow-up matters more than the original answer.
If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.
If anyone can point at the primary source I would be grateful.
Agreed on all of that, and I have nothing to add to it.
Building on post #87 rather than restating it.
Bleeding at the injection site: normal and usually minimal. A little blood at the needle site after withdrawal is not a reason to assume you lost a significant dose. The needle passed through tissue and there is a small amount of bleeding in the tract.
None of the above is medical advice and I am not qualified to give any.