Pituitary adenoma is diagnosed by three aspects: 1. clinical manifestations; 2. measurement of hormone levels; 3. imaging examinations. 1. Clinical manifestations: (1) Irregular menstruation, amenorrhea, overflowing breast for women; impotence and penile erectile disorder for men; facial deformation, enlargement of hands and feet; centripetal obesity, full moon face, buffalo back; and so on. (2) Loss of vision, visual field defects, increased urine output, headache, etc. (3) Sudden and severe headache, blindness, limited eye movement, etc. (Rarely) 2. Measurement of hormone levels: Prolactin (PRL), growth hormone (GH), cortisol (F), adrenal hormone (ACTH), testosterone, free T3, free T4, thyroid stimulating hormone TSH, etc. all change. And the magnitude of change is more than twice the normal value. 3. Imaging examinations: (1) Magnetic resonance imaging (MRI): the main diagnostic method. Pituitary microadenoma: T1-weighted image is mostly low signal, T2-weighted image is mostly high or equal signal. The pituitary stalk is slightly deviated and the saddle is subsagittal, but it is not obvious. After enhancement: the signal of pituitary microadenoma is lower than normal tissue. Pituitary macroadenoma: equal or low signal on T1-weighted image, equal or high mixed signal on T2-weighted image. The tumor is enhanced with clear borders after enhancement. Pituitary stroke: T1- and T2-weighted images show high signal, and sometimes a fluid plane is seen, suggesting tumor hemorrhage. (2) Computed tomography (CT) scan: At present, this kind of examination is rarely used for the diagnosis of pituitary adenoma, but it is valuable for judging tumor stroke.