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Endocrine System and Syndromes

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What can go wrong?

Hormones affect numerous systems throughout the body, including development of male and female sexual characteristics, fertility, growth, energy consumption, digestion, glucose utilization, stress response, fluid/water balance, and maintenance of proper blood pressure. When glands produce too much or too little of a specific hormone and affect these processes, it is known as a hormone imbalance. Some of these conditions have names, such as Cushing syndrome (associated with excess cortisol) because they are linked to a typical set of symptoms and complications.

Endocrine gland dysfunction may occur when there is a problem with the gland itself, a problem in the feedback system, and/or due to a lack of response by the hormone's target tissues. A decrease in hormone production may be related to trauma, damage by the immune system, infection, crowding of the hormone-producing cells by a tumor, or an inherited gene mutation that affects the quantity, quality, or structure of a hormone. The failure of a gland to produce and release enough hormone to stimulate the target gland to produce and release its hormone may also decrease production.

Increased hormone production may be related to a feedback system imbalance such as the pituitary gland producing too much of a hormone such as ACTH and disrupting the feedback system. Increased production may be related to hyperplasia (enlarged glands) or a tumor of the hormone-producing cells, but also can occur due to lack of tissue response, medication use, or an inherited condition.

Endocrine tumors that produce excess hormones are generally small and usually benign. Most of them are located inside the affected gland and produce a single type of hormone. Rarely, they may be cancerous. It is also very rare that endocrine-disrupting tumors may be located elsewhere in the body. A tumor may cause symptoms because of the excess hormone it is producing, because its growth crowds out and decreases the production of other hormones in the gland, or because its physical size presses against surrounding nerves and structures.

Most inherited endocrine conditions are rare and are usually related to deficient or dysfunctional production of a single hormone or to the hormone production of a particular gland (for example, congenital hypothyroidism). However, there are genetic conditions that affect multiple glands. Two that have been identified as affecting several endocrine glands are MEN-1 and MEN-2 (Multiple Endocrine Neoplasia, types 1 and 2). These conditions are related to alterations in specific genes, and they increase the lifetime risk that affected people will develop tumors in one or more of their endocrine glands.

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