Acromegaly is a hormonal disorder that results when the pituitary gland -- the gland responsible for regulating several key hormones -- produces too much growth hormone. This condition is usually caused by a tumor, but because the disease progresses so slowly, it is sometimes misdiagnosed. The most common symptom of acromegaly is abnormal growth of the hands and feet. Other symptoms include fatigue, impaired vision, and impotence.