TG and thyroiditis: These findings contrast with the increasing number of non-genetic observational studies that point towards the pleiotropic effects of thyroid function (within the normal or subclinical range) on a wide variety of endpoints.1, 2, 3, 4, 5 Possible explanations include reverse causation, by which subclinical forms of diseases raise thyroid hormone levels, or missing or imperfect adjustment for common confounders.