Aging Changes in Hormone Production

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

The hormones control the target organs. Some organ systems have their own internal control systems along with, or instead of, hormones.

As we age, 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 as we age.

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 breasts.

The thyroid gland is located in the neck. It produces hormones that help control metabolism. With aging, the thyroid may become lumpy (nodular). Metabolism slows over time, beginning at around age 20. Because thyroid hormones are produced and broken down (metabolized) at the same rate, thyroid function tests usually show results within the normal range.

The parathyroid glands are four tiny glands located around the thyroid. Parathyroid hormone affects calcium and phosphate levels, which affect the strength of the bones. Parathyroid hormone levels rise with age, which may contribute to osteoporosis.

Insulin is produced by the pancreas. It helps sugar (glucose) go from the blood to the inside of cells, where it can be used for energy.

The 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.

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 release decreases with age, which can contribute to light-headedness and a drop in blood pressure with sudden position changes (orthostatic hypotension). Cortisol release also decreases with aging, but the blood level of this hormone stays about the same. Dehydroepiandrosterone levels also drop, although the effects of this drop on the body are not clear.

The ovaries and testes have two functions. They produce the reproductive cells (ova and sperm). They also produce the sex hormones that control secondary sex characteristics, such as breasts and facial hair.

    With aging, men sometimes experience a slightly decreased level of testosterone.
    Women have decreased levels of estradiol and other estrogen hormones after menopause.

EFFECT OF CHANGES

Overall, some hormones are decreased, some unchanged, and some increased with age. Hormones that are usually decreased include:

    Aldosterone
    Calcitonin
    Growth hormone
    Renin

In women, estrogen and prolactin levels usually decrease significantly.

Hormones that remain unchanged or only slightly decreased include:

    Cortisol
    Epinephrine
    Insulin
    Thyroid hormones T3 and T4

Testosterone levels usually decrease slightly as men age.

Hormones that may increase include:

    Follicle-stimulating hormone (FSH)
    Luteinizing hormone (LH)
    Norepinephrine
    Parathyroid hormone

Aging Changes in the Male Reproductive System

Aging changes in the male reproductive system may include changes in testicular tissue, sperm production, and erectile function. These changes usually occur gradually.

Unlike women, men do not experience a major, rapid (over several months) change in fertility as they age (like menopause). Instead, changes occur gradually during a process that some people call andropause.

Aging changes in the male reproductive system occur primarily in the testes. Testicular tissue mass decreases and the level of the male sex hormone testosterone stays the same or decreases very slightly. There may be problems with erectile function. However, this is a general slowing, rather than a complete lack of function.

Fertility:

The tubes that carry sperm may become less elastic (a process called sclerosis). The testes continue to produce sperm, but the rate of sperm cell production slows. The epididymis, seminal vesicles, and prostate gland lose some of their surface cells but continue to produce the fluid that helps carry sperm.

Urinary function:

The prostate gland enlarges with age as some of the prostate tissue is replaced with a scarlike tissue. This condition, called benign prostatic hypertrophy (BPH), affects about 50% of men. This may cause problems with slowed urination, as well as with ejaculation.

In both men and women, reproductive system changes are closely related to changes in the urinary system.

EFFECT OF CHANGES

Fertility varies from man to man, and age is not a good predictor of male fertility. Prostate function is not closely related to fertility, and a man can father children even if his prostate gland has been removed. Some fairly old men can (and do) father children.

The volume of fluid ejaculated usually remains the same, but there are fewer living sperm in the fluid.

Decreases in the sex drive (libido) may occur in some men. Sexual responses may become slower and less intense. This may be related to decreased testosterone level, but it may also result from psychological or social changes related to aging (such as the lack of a willing partner), illness, chronic conditions, or medications.

Aging by itself does not prevent a man from being able to enjoy sexual relationships.

COMMON PROBLEMS

Erectile dysfunction (ED) may be a concern for aging men. It is normal for erections to occur less frequently than when a man was younger, and aging men often have less ability to experience repeated ejaculation. However, ED is most often the result of a medical or psychological problem rather than simple aging, and 90% of ED is believed to be of medical rather than psychological origin.

Medications (especially those used to treat hypertension and certain other conditions) can cause some men to be unable to develop or maintain enough of an erection for intercourse. Disorders such as diabetes can also cause ED.

Erectile dysfunction that is caused by medications or illness is often successfully treated. Talk to your primary health care provider or a urologist if you are concerned about this condition.

BPH may eventually interfere with urination. The enlarged prostate partially blocks the tube that drains the urinary bladder (urethra). Changes in the prostate gland make elderly men more likely to have urinary tract infections.

Backup of urine into the kidneys (vesicoureteral reflux) may develop if the bladder is not fully drained. If this is not treated, it can eventually lead to kidney failure.

Prostate gland infections or inflammation ( prostatitis) may also occur.

Prostate cancer becomes more common as men age. It is one of the most frequent causes of cancer death in men. Bladder cancer also becomes more common with age. Testicular cancers are possible, but these occur more often in younger men.

PREVENTION

Many physical age-related changes, such as prostate enlargement or testicular atrophy, are not preventable. Getting treatment for health disorders (such as high blood pressure and diabetes) that lead to changes in urinary and sexual health may prevent later problems with urinary and sexual function.

Changes in sexual response are most often related to factors other than simple aging. Older men are more likely to have good sex if they have continued to have sexual activity during middle age.