How hormone production changes with age

How hormonal regulation changes

The endocrine system includes organs and tissues that release hormones into the bloodstream. These chemical signals act on target organs and help regulate metabolism, growth, reproduction and many other functions. Some organs also have their own local control mechanisms.

With age, a gland may produce less hormone, release the same amount more slowly, or respond differently to signals from another gland. Target tissues may become less sensitive, while hormone breakdown can slow. As a result, circulating concentrations may fall, rise or remain much the same.

The hypothalamus and pituitary

The hypothalamus in the brain helps control other endocrine organs through the pituitary gland. Its regulating hormone output often remains broadly stable, but the receiving organs can respond differently. The pituitary reaches its largest size around middle age and then gradually shrinks. Its posterior part stores hormones made in the hypothalamus; its anterior part produces hormones that influence growth, the thyroid, adrenal cortex, ovaries, testes and breasts.

Thyroid, metabolism and bones

The thyroid in the neck produces hormones involved in metabolic regulation. It can become more nodular with age. Metabolism tends to slow from early adulthood, yet thyroid blood tests often remain normal because both hormone production and breakdown change together. Some people develop higher thyroid hormone levels, which can be associated with greater cardiovascular risk.

The four small parathyroid glands regulate calcium and phosphate through parathyroid hormone. Its level may rise with age and contribute to bone loss and osteoporosis. Thyroid and parathyroid glands are close together, but they have different roles.

Insulin sensitivity and blood glucose

Insulin from the pancreas helps glucose enter cells for energy. Cells may become less responsive to it with age, even when insulin levels have changed little. Fasting blood glucose can therefore rise, particularly after midlife. An age-related tendency is not a reason to ignore an abnormal result.

A laboratory fasting glucose of 126 mg/dL or more, equivalent to 7.0 mmol/L, is in the diabetes range. Diagnosis usually needs a second abnormal test unless the clinical picture is unequivocal. A home glucose meter cannot establish the diagnosis. Your clinician interprets results with symptoms and other tests, rather than from age alone.

Adrenal hormones, fluid balance and stress

The adrenal glands sit above the kidneys. Their outer layer produces aldosterone, cortisol and DHEA. Aldosterone helps regulate fluid and electrolyte balance. Its secretion tends to decrease with age and may contribute to a blood-pressure drop or lightheadedness when standing.

Cortisol affects how the body uses glucose, protein and fat and helps regulate inflammation and the stress response. Its release can decrease while its blood concentration remains fairly stable because clearance also changes. DHEA levels decline, but the consequences of that decline are not fully understood.

Sex hormones and reproduction

Ovaries and testes produce reproductive cells as well as sex hormones that influence features such as breast development and facial hair. After menopause, estradiol and other estrogens fall markedly. In men, testosterone usually decreases more gradually. The timing, degree and effects differ between individuals.

Common patterns in hormone levels

These are broad patterns, not a prediction for every person or a diagnosis based on one blood test.

• Levels that often decline include aldosterone, calcitonin, growth hormone and renin. Estrogen and prolactin decrease in women; testosterone generally declines gradually in men.
• Cortisol, epinephrine, insulin and thyroid hormones T3 and T4 often remain similar or decrease only slightly.
• Levels that may rise include follicle-stimulating hormone (FSH), luteinizing hormone (LH), norepinephrine and parathyroid hormone.

Use symptoms and measurements together

Discuss persistent changes in energy, weight, thirst, urination or tolerance of heat and cold with your clinician. Bring a list of medicines and supplements, since these can affect symptoms or test interpretation. Testing should answer a clinical question rather than aim to restore every value to a younger person’s level.

When an assessment is useful

Seek assessment for unexplained or worsening symptoms, recurrent dizziness when standing, or an abnormal laboratory result. Do not assume that diabetes, thyroid disease or another treatable condition is simply normal aging.

A low or high hormone result alone does not establish a need for replacement treatment. Diagnosis and any treatment decision depend on the specific hormone, symptoms, repeated or additional tests where appropriate, and your overall health.