How To Diagnose Osteoporosis

You may have heard that "bones become weak," but surprisingly many people do not know that osteoporosis gives almost no symptoms until a fracture occurs. Since there is no pain or discomfort, people often pass it by thinking "I'll be fine," only to get tested after a light fall or one overexertion breaks a wrist or spine. So osteoporosis is not "a disease diagnosed by symptoms" but "a disease found in advance by testing." In this article, I will calmly organize, from the perspective of diagnosis and testing, what the bone density test (DXA) — one of the questions most often received at Wooahan Women's Clinic — is, how to read the T-score, and when you should get tested.

The biggest trap of osteoporosis is that there are almost no warning signals such as pain or discomfort until a fracture occurs. Bone may look unchanged on the outside, but inside it constantly repeats a process in which old bone is resorbed and new bone is made; when this balance breaks and resorption outpaces formation, the inside of the bone gradually becomes sparse. Because this process progresses slowly, the person feels nothing at all.

In the clinic, there are people who passed over changes such as becoming shorter than before or having a hunched back, thinking "that's just aging," and then a spinal compression fracture is found on testing. The sites where osteoporotic fractures tend to occur are set.

• Spine: A compression fracture can occur as if collapsing, from a light impact or while lifting a heavy object.
• Hip: A hip bone fracture makes movement difficult after a fall and greatly affects quality of life.
• Wrist: It is the site most commonly broken when you put your hand down while falling.

Of course, fractures can occur in all other bones besides these three sites. The key is that you cannot rest easy just because there are no symptoms, and rather, you should confirm it in advance by testing when there are no symptoms.

The reason the bone density test is especially important for women is that there is a clear turning point called menopause. The female hormone estrogen plays the role of keeping bone from being resorbed too quickly. But when estrogen sharply decreases after menopause, this braking device weakens and the speed of bone destruction increases. The North American Menopause Society (NAMS, 2021) summarizes that bone loss after menopause is directly linked to estrogen deficiency, and that this is the largest cause of osteoporosis in postmenopausal women.

It is known that bone density can decrease relatively quickly during the few years right after menopause, and that a considerable portion of peak bone mass can be lost over a lifetime. In clinical experience, it is common for someone whose bone density was normal before menopause to have noticeably different test values just a few years after menopause. So the time around menopause is the best time to set a reference point once for "how my bones are right now."

If you are curious about the bodily changes of the climacteric in general, I also recommend reading an article organizing the mechanisms of menopausal body changes and symptoms.

The standard test for diagnosing osteoporosis is the bone density test called dual-energy X-ray absorptiometry, abbreviated DXA (or DEXA). The World Health Organization (WHO) and the International Society for Clinical Densitometry (ISCD, 2023) recommend DXA as the reference test for measuring bone density. It uses a small amount of X-rays to measure the bone mass mainly of the spine (lumbar vertebrae) and hip (femur), and the test itself is over in a short time, lying down, without pain.

What DXA measures is the amount of bone per unit area, that is, bone density. This value is compared with a reference group and converted into a score, and what comes out of this is precisely the T-score and Z-score. Because the test is simple and radiation exposure is low, it is a test that can be taken without burden if osteoporosis is suspected or there are risk factors.

In the clinic, many people are confused about which number to look at because various site values appear on the test result sheet. Generally, the diagnosis is judged based on the lowest value among the measured sites, and the key to interpreting its meaning is the T-score explained next. Taking the same test again after a time interval also lets you check the trend of whether the bone state is improving or worsening.

The T-score is a value showing, in standard deviation units, how much my bone density differs compared with the average of a "healthy young adult." The average of a young adult is 0, and the more the number goes into the minus, the more it means the bone is that much lacking. According to the World Health Organization (WHO) criteria, the T-score is interpreted as follows in postmenopausal women and men aged 50 and over.

There is a point to note here. Osteoporosis is diagnosed when the T-score is -2.5 or lower, that is, -2.5 or lower than that. People sometimes mistakenly remember "above -2.5 is osteoporosis," but the direction is reversed. If you remember that the smaller the number (the more negative), the weaker the bone, you will not get confused.

One more thing: the T-score is a criterion applied to postmenopausal women and men aged 50 and over. For premenopausal women, men under 50, and children and adolescents, the Z-score, which compares with the same age group, is used instead of the T-score, and in this case, osteoporosis is not concluded from a single test value alone — this is the position of the International Society for Clinical Densitometry (ISCD, 2023). If you have received a result sheet, it is important to interpret it by the criterion that fits your age and menopausal status.

The reason the T-score is important is that it is not a mere number but is directly linked to future fracture risk. It is reported that the lower the bone density and the older the age, the higher the likelihood of a future osteoporotic fracture. Even with the same T-score, fracture risk is assessed as higher in older people, because beyond bone density, age itself is an independent risk factor.

So recently, instead of looking at the T-score alone, tools are sometimes used that comprehensively assess future fracture risk by also factoring in age, past fracture history, family history of fracture, smoking, weight, and so on. Even if bone density is borderline, active management may be needed if risk factors overlap, and conversely, even if the value is low, an accurate judgment is possible only by looking at the whole context together.

In the clinic, I often meet two extremes: being overly anxious over a single number on the test result sheet, or, conversely, feeling reassured saying "it's not osteoporosis yet, so it's fine." Neither is the right answer. The result must be interpreted within the whole picture of my age and risk factors, and that judgment is safest when looked at together through gynecological care.

So when should you get a bone density test? Even with no risk factors at all, women aged 65 and over and men aged 70 and over are recommended to get a bone density test. If there are risk factors, it is good to test earlier regardless of age.

Representative situations in which to consider testing earlier are as follows.

• Having reached menopause at an early age or having early decline of ovarian function
• Having a parent or sibling with a history of hip fracture
• Having experienced a fracture even from a light impact
• Having used drugs that affect bone, such as steroids, for a long time
• Having low body weight or smoking or drinking excessively

In Korea, women aged 54 and 66 can receive a bone density test through the national health checkup, so it is good to use this time as a testing opportunity (National Health Insurance Service). It is not over with one test; it is important to measure again at certain intervals according to the result and risk and to check the change. That said, for a postmenopausal woman with low fracture risk, it is reported that there is no need to set the follow-up test interval too short (NAMS, 2021).

The detailed composition of menopausal screening can be checked in menopause screening information, and the importance of regular checkups is further covered in why you should not put off regular gynecological checkups.

Confirming bone density by testing is not the end but the beginning. Osteoporosis is a disease for which prevention is far more important than treatment, and bone health actually starts with building up bone sufficiently in childhood and adolescence. The more bone mass accumulated when young, the more leeway there is in old age even if bone decreases at the same rate.

The basics you can practice in daily life are clear. Take in enough calcium and vitamin D, and move your body regularly within a non-strenuous range. Exercise need not be grand; you can start from light stretching, and continuing steadily, with about 30 minutes three times a week as a guide, helps. For menopausal women who are prone to vitamin D deficiency, please also refer to the story of menopause and vitamin D.

If you are around menopause, management methods including hormones can be reviewed together through care. If you want to organize what osteoporosis itself is from the basics again, I recommend reading on with an article explaining what kind of disease osteoporosis is, and for how to prevent fractures along with menopause, diagnosis and prevention of menopausal osteoporotic fracture. If hormone management is needed, you can get a consultation on a method suited to your individual situation at menopausal hormone care.

The best time to test is when there are no symptoms. If you are curious about your bone density state or unsure about the timing of testing, please feel free to leave a consultation.

Written by Lee Dong-hee, Director · OB-GYN specialist · See physician profile

First published January 4, 2024 · Last reviewed May 30, 2026

References: World Health Organization bone density diagnostic criteria (2024), International Society for Clinical Densitometry Official Positions (2023), North American Menopause Society osteoporosis management recommendations (2021), National Health Insurance Service national health checkup bone density test information (2024)

This article is intended to provide general health information and does not replace individual diagnosis or treatment. If you have symptoms, please consult through a medical visit.