@Bookgrrrl
Humans aren’t mathematical equations, not everyone reacts the same to the same levels of things (which is precisely why there is a range), so while ‘borderline’ can be fine for one person, another person can feel terrible at that level.
I agree, things like body weight/mass, general health, fitness, etc., all come into the equation, especially re the impact of drugs etc.
My OH's first week of chemotherapy for his cancer nearly killed him. So much so that the second week had to be cancelled. When they did the blood tests, his "scores" for the blood cancer markers had halved! The consultant couldn't believe it and said that kind of effect usually happens after two full rounds of the chemotherapy, not just half of the first round.
It took my OH to suggest to the consultant to use a lower dose of the chemotherapy for the next round the month after. (He'd researched the drug and found that there were 3 different strengths and he'd been started on the highest!). Thankfully, the consultant agreed, and he had the middle strength for month 2, and the blood cancer markers halved again.
He was still very poorly, so asked the consultant to give the lowest strength for the third month. Consultant agreed. And the blood cancer markers halved again, to virtually zero. Instead of a six month course of chemotherapy, the consultant decided to stop after three months.
He said he'd never seen anything like it and said he had "reported it up the chain" whatever that means.
OH also chose not to go through the next stage of "normal treatment" which was a stem cell transplant. Consultant and the stem cell consultant both told him his life expectancy could be as low as 18 months without it!
He's now on permanent low dose chemotherapy drugs and, again, despite the consultant putting him on the highest dose at the start, causing all kinds of side effects, he asked the consultant to reduce, and no he's not only on the lowest does, but also not even taking them every day like he should, but taking them every other day, and having two weeks off between cycles instead of one week. Blood cancer markers still remarkably low and no sign of them increasing.
So yes, different people, different bodies, react in different ways to medication. He's now survived six years after they gave him a life expectancy of 18 months!
Doctors etc need to stop basing all their decisions on their text books and start to properly listen to their patients, take more "holistic" approaches, etc. I think this is why, as a couple of other posters have mentioned, that sometimes more alternative methods of treatment/care may work better - simply because they're more likely to listen to the patient and look at the "whole" rather than the individual symptoms/markers.