What is the X in X-mas?
"of or near the kidneys," 1866, Modern Latin, from ad- + renalis "of the kidneys," from Latin renes "kidneys." Adrenal gland is from 1875.
adrenal ad·re·nal (ə-drē'nəl)adj.
At, near, or on the kidneys.
Of or relating to the adrenal glands or their secretions.