The Master Gland

The major endocrine gland, a pea-sized body attached to the base of the brain that is important in controlling growth and development and the functioning of the other endocrine glands
It is  found at the base of the brain. As the “master gland” of the body, it produces many hormones that travel throughout the body, directing certain processes or stimulating (causing) other glands to produce other hormones.
The pituitary gland has two parts—the anterior lobe and posterior lobe—that have two very separate functions.
The pituitary gland makes or stores many different hormones.

• Adrenocorticotropin (ACTH) - ACTH stimulates the production of cortisol by the adrenal glands—small glands that sit on top of the kidneys. Cortisol, a "stress hormone," is vital to our survival. It helps maintain blood pressure and blood glucose (sugar) levels, and is produced in larger amounts when we’re under stress—especially after illness or injury.

• Prolactin - Prolactin stimulates breast milk production after childbirth. It also affects sex hormone levels from ovaries in women and from testes (testicles) in men, as well as fertility.

• Growth hormone (GH) - GH stimulates growth in childhood and is important for maintaining a healthy body composition and well-being in adults. In adults, GH is important for maintaining muscle mass and bone mass. It also affects fat distribution in the body.

• Luteinizing hormone (LH) - LH stimulates testosterone production in men and egg release (ovulation) in women.

• Follicle-stimulating hormone (FSH) - FSH promotes sperm production in men and stimulates the ovaries to produce estrogen and develop eggs in women. LH and FSH work together to enable normal function of the ovaries and testes.

• Thyroid-stimulating hormone (TSH) - TSH stimulates the thyroid gland to produce thyroid hormones, which regulate the body's metabolism, energy balance, growth, and nervous system activity. 

The problems caused by pituitary tumors:

Hypersecretion: Too much of any hormone in the body is caused by a secretory pituitary tumor.

Hyposecretion: Too little of any hormone in the body can be caused by a large pituitary tumor, which interferes with the pituitary gland’s ability to produce hormones. Hyposecretion can also result from surgery or radiation of a tumor.

Tumor mass effects: As a pituitary tumor grows and presses against the pituitary gland or other areas in the brain, it may cause headaches, vision problems, or other health effects.