Aging Effects – Part 03

Age-related endocrine changes include alterations in the secretion, circulating levels, metabolism, and biologic activity of hormones. There is also a loss of circadian (a 24-hour period) control of hormone secretion.Although most glands decrease their levels of secretion, normal aging usually does not lead to a deficiency state. For example, while the adrenal cortex decreases its secretion of cortisol, negative feedback mechanisms maintain normal plasma levels.As the thyroid gland changes, there will be a decrease in the secretion of the thyroid hormones which will lead to a decrease in the metabolic rate. One of the results from this is an unawareness of temperature. There will be an intolerance to cold and hot days will not be noticed, thereby increasing the risk of heat stroke.A decrease in the secretion of the growth hormone causes a decrease in the muscle mass and an increase in the storage of fat.

Blood and tissue concentrations of many other hormones remain unchanged (TSH, thyroid hormones, ADH, PTH, prolactin, and glucocorticoids). Despite unchanging hormone levels, some endocrine tissues become less responsive to stimulation. For example, there is less GH (growth hormone) and insulin secreted after a carbohydrate-rich meal or during a glucose tolerance test.

Peripheral tissues become less responsive to some hormones, particularly glucocorticoids and ADH. The failure to produce enough glucocorticoids can affect metabolism and the inability to deal with stress. In addition, a decline in production will also reduce the anti-inflammatory and immunosuppressive qualities that they give. This means that the elderly are more prone to pain and infections.