Medical Health Encyclopedia

Aging changes in hormone production

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.

Less thyroid hormone may be produced, but there is also less body mass (because of loss of muscle and bone tissue), so that thyroid function tests usually show results within the normal range.

The parathyroids are four tiny glands located around the thyroid. Parathyroid hormone affects calcium and phosphate levels. This, in turn, affects the strength of the bones. Changes in the level of parathyroid hormones may contribute to osteoporosis.

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Insulin is produced by the pancreas. Insulin hormone fits into a place on the cell wall called an insulin receptor site, and acts like a lock and key to help sugar (glucose) go from the blood to the inside of cells, where it can be used for energy.

The normal or average fasting glucose level rises 6 to 14 mg/dL (milligrams per deciliter) for each 10 years after age 50. This is because the cells become less sensitive to the effects of insulin, probably because of a loss in the number of insulin receptor sites in the cell wall.

Because of these changes, older people periodically should have blood drawn to check glucose levels and make sure they aren't in the early stages of diabetes, or high blood sugar.

The adrenal glands are located just above the kidneys. The adrenal cortex, the surface layer, produces the hormones aldosterone and cortisol.

• Aldosterone regulates fluid and electrolyte balance.
• Cortisol is the "stress response" hormone. It affects the breakdown of glucose, protein, and fat, and has anti-inflammatory and anti-allergy effects.

Aldosterone secretion decreases with age, which can contribute to light-headedness and a drop in blood pressure with sudden position changes (orthostatic hypotension). Cortisol secretion decreases, but the level stays about the same.