The range called "healthy" has nothing whatsoever to do with me (or you), in particular, with your shades of gray, and your affection for Evelyn Waugh's Brideshead Revisited. A mosquito and an opossum are both animals. That's science. The nuance, however, is everything. And that's something medical science, with it's concern for populations, and public health, has to put hip waders on for. It's deep out there, and current-y, when it comes to individual lives and our wee sprites of individual ranges. What's more than enough calcium for you to build your shell, may be way less than I need, you know what I mean?
Of course, no argument from me, it is overwhelming to think of a population as the many souls within it. Individuals. Red heads. People who like cats. Like, actually like them. People who can have just one Thin Mint. We are so very different, and I like that about us. (How can you have only one Thin Mint. I mean, really?)
But, when it comes to my thyroid, or anything else really, like, oh, say my ovaries, do I really want the same range as a 300 lb male trucker from St. Louis?