abnormal adrenal gland x-zone size small adrenal gland x-zone 2014-04-29T00:00:00Z MP:0020144 MPheno.ontology nvasilevsky reduced size of the x-zone compared to the average on the pair of endocrine glands located above the kidney that are responsible for steroid hormone secretion from the cortex and neurotransmitter (such as epinephrine and norepinephrine) secretion from the medulla small adrenal gland x zone