My vitamin d has been low (that I know of) since mid-2017. When I had lab work in July 2017, my vitamin d was 21 ng/mL. In August 2018, it was 23 ng/mL. My latest bloodwork in Oct 2019 shows my vitamin d is 20 ng/mL. What are some potential causes for this deficiency provided that I’m not deficient from a dietary perspective? Are there any specific ‘conditions’ that I should be screened for in order to help determine why I’m vitamin D deficient? Is this question even possible to shed light on without more information?
The first question would be why the vitamin D level was ever checked in the first place, i.e., were there specific signs, symptoms, or other lab findings that prompted it being checked. A level in the 20s usually isn’t particularly problematic on its own.
Vitamin D physiology is complex. It is occasionally low due to dietary / true environmental deficiency, although this is less common.
It is also known as a “negative acute phase reactant”, meaning that it tends to decrease in the setting of other ongoing issues (which is what we see more commonly, e.g., Obesity/metabolic syndrome, other inflammatory conditions, etc.)
Without any other information about you we can’t provide recommendations about subsequent evaluation though.