Aging changes in hormone production

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Female reproductive anatomy

Menopause

The endocrine system is made up of organs and tissues that produce hormones. Hormones are natural chemicals produced in one location, secreted into the bloodstream, then used by certain other target organs and system.

The hormones control the target organs. Some organ systems have their own internal control systems instead of, or in addition to, hormones.

With aging, changes naturally occur in the way that body systems are controlled. Some target tissues become less sensitive to their controlling hormone. The amount of hormones produced may also change.

Blood levels of some hormones increase, some decrease, and some are unchanged. Hormones are also broken down (metabolized) more slowly.

Many of the organs that produce hormones are, in turn, controlled by other hormones. Aging also changes this process. For example, an endocrine tissue may produce less of its hormone than it did at a younger age, or it may produce the same amount at a slower rate.

AGING CHANGES

The hypothalamus is located in the brain. It produces hormones that control the other structures in the endocrine system. The amount of these regulating hormones stays about the same, but the response by the endocrine organs can change with aging.

For example, a hormone called TRH makes the pituitary gland produce thyrotropin, or thyroid stimulating hormone (TSH). In women, the amount of TSH produced does not decrease with time, but it does in men.

The pituitary gland is also located in the brain. This gland reaches its maximum size in middle age and then gradually becomes smaller. It has two parts:

• The back (posterior) portion stores hormones produced in the hypothalamus.
• The front (anterior) portion produces hormones that affect the thyroid gland (TSH), adrenal cortex, ovaries, testes and the breasts.

The thyroid gland is located in the neck and produces hormones that help control metabolism. With aging, the thyroid often becomes lumpy (nodular). Metabolism gradually declines, beginning about age 20.