Slightly thickened left adrenal gland may be caused by proliferation of adrenal cortical cells, adrenal nodule, adrenal adenoma, etc. Patients can be observed regularly in outpatient clinic or treated by oral adrenocorticotropic hormone or surgery for removal of adrenal adenoma. 1. Proliferation of adrenal cortical cells: the left adrenal gland is slightly thickened on the inner side, which may be caused by proliferation of adrenal cortical cells. A few cases will cause increased hormone secretion, but most of them are non-secretory and will not affect the endocrine hormone level of the adrenal glands, and it is recommended to observe regularly in outpatient clinic and can be left untreated at the first place. 2. Adrenal nodule: adrenal nodule may cause the patient’s left adrenal gland to appear thickening phenomenon. It can be treated by oral adrenocorticotropic hormone, such as dexamethasone acetate tablets, hydrocortisone tablets, etc. It is forbidden for patients who are allergic to the drug components or have high blood pressure. 3. Adrenal adenoma: the role of adrenal glands is to secrete hormones, and adrenal adenoma may lead to the phenomenon that the left adrenal gland is slightly enlarged on the inner side. Adrenal adenoma can be treated through adrenal adenoma removal surgery, after which attention should be paid to nutritional balance and wound healing. When the patient has the phenomenon of left adrenal gland medial thickening, it is recommended to consult a doctor for examination in time, identify the cause of the disease and then follow the doctor’s instructions to use medication, do not use medication privately, so as not to aggravate the condition.