Hormone and Nutrient Testing in Aging: When Tests Help

What this page covers

Blood tests for hormones and nutrients are popular in longevity and anti-aging programs. This page explains what guideline bodies say about when such tests are useful, and where they say the evidence is lacking. It is information only: it does not tell you which tests to order, how to read your numbers, or whether to start or stop any supplement or medicine. Please talk with your own clinician about your situation. Evidence labels used: established (guideline-supported), insufficient evidence, no good evidence of benefit and marketing claim.

The general idea

A test is most helpful when someone has symptoms or a known risk and the result changes what a clinician will do. The "normal range" comes from groups of healthy people, labs often use different ranges, and it is common for healthy people to sometimes fall outside the range, so a result outside the range is not automatically a problem. [1] See Interpreting Test Results Without Overinterpreting.

Summary by test

Testosterone

The Endocrine Society's 2018 guideline recommends diagnosing low testosterone only in men with symptoms and signs of deficiency plus unequivocally and consistently low blood levels. [2] It recommends a fasting morning total testosterone as the first test, confirmed by repeating it. [2] Even guideline groups differ on older men: the Endocrine Society and the Endocrine Society of Australia agree that men with an intact hormone system may have low levels, for instance older men or men with obesity, but the Australian society did not recommend treatment for them and the two groups use different reference ranges. [8] A test result is not a treatment decision. For trial evidence on treatment, see Testosterone Therapy and Aging; for everyday background see Low Testosterone.

Menopause and midlife hormones

NICE's guideline says that in otherwise healthy people aged 45 or over with symptoms, perimenopause and menopause should be identified without laboratory tests. [3] It also says not to use tests such as oestradiol, anti-Müllerian hormone or inhibin to identify perimenopause or menopause in people 45 and over. [3] A blood FSH test may be considered to confirm menopause only in people aged 40 to 45 with symptoms and in people under 40 in whom it is suspected. [3] This is a UK guideline; other countries may differ. See Menopause, Midlife Hormone Changes and Healthy Aging.

Vitamin D

The US Preventive Services Task Force (2021) found the evidence insufficient to weigh benefits and harms of screening for vitamin D deficiency in adults without symptoms. [4] That statement does not apply to hospitalized people or people living in institutions. [4] The Endocrine Society's 2024 guideline suggests against routine 25(OH)D testing without an established indication and notes that more research is needed to determine optimal levels for specific benefits. [5] So there is no proven "longevity target" for the number. For nutrient background see Vitamin D Deficiency and Testing.

Vitamin B12

The NHS says a diagnosis of B12 deficiency anaemia can often be made by a GP from symptoms and blood tests, and that symptoms should be taken into account. [6] Some people have symptoms and seem to have normal levels, and some have low levels without symptoms. [6] See Vitamin B12 Deficiency.

Thyroid

The task force concluded in 2015 that the evidence was insufficient to assess screening for thyroid dysfunction in nonpregnant adults without symptoms. [7] This statement is older, so check current guidance with your clinician.

Not covered

Growth hormone, IGF-1, DHEA and similar "anti-aging" hormone panels: Proper evidence not found in the guideline sources read for this page that supports routine testing in healthy adults. Treatment trials are discussed on Growth Hormone and IGF-1 in Aging Research.

Who should be extra careful

Anyone on prescription medicine, and anyone considering a supplement or hormone treatment based on a single result, should discuss it with their prescriber first. For example, the Endocrine Society lists prostate cancer, untreated severe obstructive sleep apnea and uncontrolled heart failure among conditions in which it recommends against starting testosterone therapy. [2]