Symptoms vary based on the tumor's size, where it is and whether it secretes or not. They may include:
- Overproduction of hormones. Functional tumors, which secrete hormones, can produce too much hormones. Almost 20% secrete prolactin, a hormone that causes milk production in women. Very high levels can cause milk production in men and women who are not pregnant. Menstrual irregularities may also occur.
- Underproduction of hormones. Some 75% of pituitary tumors don't produce hormones. These can grow and damage normal gland tissue. This cuts hormone production. Often the first hormones affected are those that relate to sex. This can cause irregularity or loss of menstruation in women and sterility with loss of sex drive in men and women.
- Growth disorders. These cause excessive growth (gigantism) in children. In adults, they cause acromegaly, or abnormal growth of the face bones, enlarged hands and feet, excessive sweating and heart disease.
- Disturbances in vision will occur if the tumor presses on the optic nerves.