Pituitary tumors causing hormonal excess are called functioning pituitary tumors. Acromegaly, Cushing's disease and prolactinomas are the most common.
Acromegaly is caused by a pituitary tumor that produces excess growth hormone (GH). It most commonly affects middle-aged adults and can result in serious illnesses or premature death. If the disease develops before a person has stopped growing, it causes gigantism since too much GH promotes the growth of bones in the body. The most common symptoms of GH excess are enlargement of the hands, feet, and face and excessive sweating. Patients may also experience headaches, irregular periods (in women), impotence (in men), and peripheral vision loss. Patients may also have an enlarged heart, tingling or pain in extremities (peripheral neuropathy), and excessive sleepiness during the day (sleep apnea). Because of its slow onset, acromegaly may go undiagnosed for many years. Once recognized, acromegaly is treatable in most patients. The primary treatment is usually surgery followed by radiotherapy or medications that decrease GH excess.
Cushing's disease refers to a pituitary adenoma that produces excess ACTH, which stimulates cortisol secretion by the adrenal glands located above each kidney. Patients with Cushing's disease have progressive weight gain, muscle weakness, easy skin bruising, impotence (in men), irregular periods (in women), and depression. Patients also have high blood pressure, diabetes, and osteoporosis. Many of these problems are non-specific, meaning that people who have them may not have Cushing's disease. On the other hand, most patients who have Cushing's disease exhibit some, if not all, of these symptoms.
There is a characteristic appearance in many patients with Cushing's disease which includes a round face, the excess fat pad in the back of the neck ("buffalo hump"), excess fat in the collarbone area, weight gain primarily in the abdominal region with relative thinning of the arms and legs, and red abdominal stretch marks.
Diagnosis of Cushing's disease is sometimes challenging and has to be done by an experienced endocrinologist. The treatment is usually pituitary surgery, which needs to be done by an experienced neurosurgeon. Radiotherapy may be used in some patients that are not cured by surgery. Medical therapy plays a limited role in the management of Cushing's disease. In the majority of cases, surgical curative treatment of Cushing's disease leads to improvement of most of the symptoms mentioned.
Prolactinomas are benign tumors of the pituitary gland that produce excessive amounts of the hormone prolactin. Symptoms result from too much prolactin in the blood (hyperprolactinemia) or pressure from the tumor on surrounding tissues (if the tumor is large). Hyperprolactinemia causes milk discharge from the breast (galactorrhea), menstrual irregularities (oligomenorrhea or amenorrhea) and infertility in women, and impotence in men. Prolactinomas are usually successfully treated with medications that shrink the tumor, even if large. Some prolactinomas require surgery. Hyperprolactinemia does not mean that the patient has a pituitary tumor since it can occur in patients who take certain medications or have other medical conditions. Evaluation by an endocrinologist is necessary to differentiate these conditions.