If not, it is a good indication that there are low tissue levels of thyroid. (verywellhealth.com)
We all have some exposure to various heavy metals, but those who have worked in chemical industries over the years would have higher tissue levels. (novaholisticjournal.com)
For cells to have major functional differences they need to express many genes together that are specific to the function, which will be reflected on a whole tissue level. (sangerinstitute.blog)