Diminution or cessation of secretion of one or more hormones from the anterior pituitary gland (including LH; follicle stimulating hormone; SOMATOTROPIN; and CORTICOTROPIN). This may result from surgical or radiation ablation, non-secretory pituitary neoplasms, metastatic tumors, infarction, pituitary apoplexy, infiltrative or granulomatous processes, and other conditions.