DXA scans, FRAX and other tests for osteoporosis

The standard way of measuring bone density is a simple test called dual x-ray absorptiometry (DXA). The DXA scan is an accurate and reliable technique of assessing the strength of bones. A DXA scan usually measures bone mass (the amount of bone) in the spine and hip and wrist – parts of the body which are more at risk of osteoporotic fractures. Ultrasound can also be used to assess bone strength but cannot be used to monitor treatment.
A DXA scan measurement provides an assessment of a person’s bone density and his/her likelihood of having a fracture; it is also used to help decide if medication is needed. There is no national screening programme for osteoporosis but at present a doctor would request a DXA scan for a patient with strong risk factors such as maternal history of the condition, early menopause and use of oral corticosteroids. Using risk factors, together with height and weight, your GP can use the WHO FRAX tool to decide whether you need a DXA scan or whether the risk is high enough to warrant treatment (see also Who develops osteoporosis?).
A DXA scan involves lying on a couch whilst a thin metal arm moves up and down taking an image of the spine and hips. Clothes do not need to be removed, except for garments with metal at the hips or along the spine (trouser zips are fine). No injection or mechanical tunnel (like for an MRI scan) is involved in the procedure.
The level of radiation of a DXA scan is lower than that of an ordinary x-ray and more similar to natural daily radiation levels. The whole procedure takes between ten to twenty minutes and no one we talked to found it unpleasant.

Valerie talks about her experience of having a DXA scan.

Age at interview 67

Gender Female

Age at diagnosis 63

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Many people requested their DXA scan through their GP, in many cases because their mother or father had osteoporosis, and/or after they had been using hormone replacement therapy (HRT). In other cases the GP initiated the scan after a wrist fracture or a complaint of back pain for some time – as in the cases of Carol and Alice respectively. In some cases x-ray results prompted hospital doctors to send patients like Jane for further investigations including a DXA scan. And others, like Iris, happened to attend fracture clinics in hospitals that routinely screen postmenopausal women with a fracture for osteoporosis. Doctors in fracture clinics made the postmenopausal women we talked to aware of the need to have a DXA scan. Gloria was told to ask her GP for one. Jenny however, had worried about osteoporosis long before her diagnosis and asked for a bone density scan to find out the impact of a dairy-free diet on her bones. For almost twenty years Jenny managed her ME and other allergies by not consuming dairy products. Joan made an appointment and paid for her first DXA scan at a private hospital because she realised her back was becoming bent and her mother had osteoporosis.

Linda had a DXA scan after stopping HRT which showed a slightly below normal result. Three years…

Age at interview 62

Gender Female

Age at diagnosis 60

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Not all hospitals have DXA scans. Some GPs can offer a DXA scan on the NHS but in areas where resources are scarce, people may have to pay for the scan themselves. People who were diagnosed many years ago often had to travel to have a DXA scan since fewer scanners were available then. But the situation has improved. People diagnosed in the last five years tend to have a scan done on average every three years. A few have been told by their GP’s that subsequent scans will be done every five years. Apart from DXA scans other tests, like blood and urine tests are also used to measure bone loss, predict fracture risks and to check the person’s response to the medication (see below).

In a few cases and thanks to the fund raising activities of local support groups, hospitals have been able to get a DXA scanner and a printer to print the results that are sent to the GP. Pat, however, continues to pay for hers privately because in the city where she lives no NHS hospital has the facility.

Pat was involved in successfully campaigning for a DXA scanner which is now available at her…

Age at interview 68

Gender Female

Age at diagnosis 54

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Valerie who was diagnosed four years ago waited ten days to have her first DXA and had her second…

Age at interview 67

Gender Female

Age at diagnosis 63

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Waiting times for a bone scan vary. After their GP requested a DXA scan some people received an appointment within a couple of weeks while others waited for 3-4 months. Moreover, people’s perception of ‘a long wait’ also differed. For Gloria a 3 months wait ‘wasn’t very long’ while Susan experienced 3 months as ‘waiting for ages’.

But Gloria waited a year for her second DXA scan after diagnosis and was anxious to know if the medication was working. After almost a year she learnt from the hospital that the request for another scan was pending and hadn’t even got on to the appointment list. She wrote to the Health Minister about it.

After waiting for a year to have a second bone density scan Gloria wrote to the Minister of…

Age at interview 66

Gender Female

Age at diagnosis 58

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A DXA scan is generally used to decide if a person needs medication. A few people hadn’t needed medication at first because their bone density was not sufficiently low, but a later scan showed the need for it.

Many people felt that regular scanning gave them an accurate assessment of the strength of their bones and reliably monitored their treatment. Many were eager to know whether the medication had produced the expected improvement, had made no difference or, worse, if their bones had got thinner. Knowing that the bone density had improved made people confident about their treatment.

Emma is taking strontium ranelate and would like her GP to refer her to have a scan more…

Age at interview 61

Gender Female

Age at diagnosis 47

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David who has had arthritis most of his life and was diagnosed with osteoporosis when he was 23,…

Age at interview 25

Gender Male

Age at diagnosis 23

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Margery has had six DXA scans that over the last twelve years have monitored the effectiveness of…

Age at interview 72

Gender Female

Age at diagnosis 58

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The frequency of scans varied. Some people were told they could have a scan on the NHS every two or three years to see if their medication was working. But most had to ask their doctor as it wasn’t automatically offered to them. Joan was taking strontium ranelate and had an annual bone density scan. People who paid for a scan privately could have one more frequently.

Some people had scans less often. Neville and Sarah had a scan at the time of their diagnosis several years ago but haven’t had one since. A few people said it had been five years or more since their last scan but they hadn’t felt the need to have another so hadn’t asked for one.

Clare took part in a couple of surveys on osteoporosis, which led her to see her GP and request a…

Age at interview 65

Gender Female

Age at diagnosis 64

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Chris hasnt had a scan for a while because her nearest DXA scanner is quite a distance away and…

Age at interview 52

Gender Female

Age at diagnosis 45

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Several women who at the time of their fracture were not offered a DXA scan felt upset about the lack of preventive medicine because their diagnosis and treatment was delayed, sometimes for years (see Being diagnosed with osteoporosis).
Several close relatives of the people we talked to requested a DXA scan themselves to find out if they had osteoporosis. For most of these people, their GP arranged this. Diana’s and Sheila’s daughters, have also been diagnosed with the condition. But Laurence feels frustrated that his daughter and also his wife with a maternal history of the condition were denied a scan.

Despite having a maternal history of osteoporosis, Laurences wife was denied a DXA scan on the…

Age at interview 62

Gender Male

Age at diagnosis 54

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The results of the DXA scan are usually sent to the GP with whom people can discuss the results. Accurate interpretation of results depends on repeat scans being performed on the same machine, especially if they are being used to monitor a treatment or bone loss. For a few people comparisons couldn’t be made because their tests had been done on different scanners. To get around this problem Jenny paid for her subsequent scans to be done on the original machine after her GP clinic started arranging DXA scans at another hospital. Having her scans done there would have made it impossible to compare previous scan results with newer ones.

In some parts of the UK support groups have raised funds to buy or contribute to the cost of a DXA scanner to ensure that one is available locally ensuring that patients’ scan results can be compared accurately.

Anns local support group raised money to donate a DXA scanner and computer to their hospital, so…

Age at interview 69

Gender Female

Age at diagnosis 62

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Margerys support group found out that other specialists in the hospital didnt know they had a…

Age at interview 72

Gender Female

Age at diagnosis 58

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Evidence suggests that a bone scan may not be the best way to assess fracture risk in the elderly because degenerative conditions of the spine such as osteoarthritis may occur as part of the ageing process. In turn, this can affect the reading of a DXA scan hence giving a misleading estimate of a person’s bone mass. This happened in Joan’s case.

Changes in Joan’s spine affected the accuracy with which her bone mineral density (BMD) could be…

Age at interview 73

Gender Female

Age at diagnosis 69

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Blood and urine tests: biochemical markers

During bone remodelling substances are produced which can be detected in the blood and urine. These are known as biochemical bone markers. The levels of these markers can be used to measure the rate of bone turnover, giving useful indicators of bone strength and future fracture risks. Blood and urine tests alone cannot diagnose osteoporosis, people also need a DXA scan, but can be used to assess the effectiveness of treatment. Most treatments for osteoporosis work by reducing the rate of bone turnover, so monitoring bone loss with this technique may help with dosage adjustments of medication or help indicate the need to change to another medication if bone turnover is not reduced or back to normal within six months.

Some units use biochemical markers instead of DXA for monitoring treatment, the tests are a bit awkward; the patient has to fast and the sample must be taken at the same time of day each time. A few people told us that the biochemical markers of bone turnover are being used to assess their response to the prescribed medication.

Diana has blood tests now instead of DXA scans.

Age at interview 77

Gender Female

Age at diagnosis 72

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Being diagnosed with osteoporosis

Throughout life, the skeleton continually renews itself through a process known as remodelling or bone turnover. In healthy bone, the rate of bone breakdown is...

Who develops osteoporosis?

Throughout life, the skeleton is continually renewing itself through a process known as remodelling or bone turnover. In healthy bone, the rate of bone breakdown...