Q. What does it mean when Robbins says the adrenal cortices are hyper- and hypoplastic?

A. Hypoplastic adrenal cortices mean that the adrenal cortices have atrophied; hyperplastic adrenal cortices mean that they have expanded. You’d see hypoplastic adrenal cortices in situations where there is not very much ACTH stimulation (so the cortices would shrink). For example, when you take oral steroids, or when there’s an adrenal cortical tumor, the pituitary sees all that cortisol floating around, and it cuts down its secretion of ACTH.

Hyperplastic adrenal cortices occur when there is a lot of ACTH stimulation. For examle, if there’s a pituitary tumor, or a lung carcinoma secreting ACTH like substance, then the adrenal cortices are hyperplastic. Hyperplasia can occur on its own, too, as a primary adrenal disorder.