Doctors have assumed the adrenal glands do not regrow after removal. However, there are some anecdotal observations of regrowth in humans and animals.
In a 2018 animal study, researchers found significant levels of adrenal hormones in rats after removing their adrenal glands. Of these rats, regenerated adrenal tissue was present in some, but not all. Researchers hypothesize various compensatory mechanisms after removal may be responsible for the regrowth.
There are very limited human studies on this topic. More clinical research is needed to explore this hypothesis.