I live in Seattle and taking 2000 UI daily barely got me to “sligtly deficient”. Now I upgraded to 4000 UI daily hoping to get to the lower part of the normal r

I live in Seattle and taking 2000 UI daily barely got me to “sligtly deficient”. Now I upgraded to 4000 UI daily hoping to get to the lower part of the normal range. I talked to the doctor and she told me that among blood tests she ordered most people have slightly/moderately deficient levels, very few low normal, and over the years only one person tested high normal (i.e. when taking supplement would be detrimental). Moral of the story - do a blood test, but if you live in high-ish lattitudes, most likely you have vitamin D deficiency.