JessicaM_2024 said:

Update: the thing I was blaming turned out not to be the cause.

Mine went the same way, slower. The detail I would add is minor and it is already implied above.

JessicaM_2024 said:

Update: the thing I was blaming turned out not to be the cause.

There is a second half to this that has not been said yet. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.

One concrete data point for the thread. Keep the original post as written when you update it, and add the correction underneath. An edited-away mistake is invisible to the next person who makes it.

Following on from JessicaM_2024 — and this may be the naive question:

Did your prescriber agree with that reading, and if not what was their objection?

kate.chem said:

Keep the original post as written when you update it, and add the correction underneath.

Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. The objection nobody has made: this only works if the measurement is doing what we assume it is doing, and that assumption has not been tested here.