Osteoporosis in Anorexia Nervosa:
Information for clients and carers
Osteoporosis is a common complication of anorexia. Osteoporosis is a progressive skeletal
disease which leads to a reduced bone mass and reduction in the strength of your bones. This
leads to increased bone fragility and susceptibility to fracture, which can persist long after
successful treatment for anorexia. The majority of patients do not realise that they have the
disease until they sustain a fracture. Osteoporosis left untreated can lead to fractures, spinal
deformity and persistent pain and disability.
If you have been diagnosed with anorexia and have not menstruated for a year or more you are
at risk of osteoporosis. Half of all women with anorexia have osteoporosis and half of all men
with anorexia have substantial bone loss. Clinically significant bone loss usually does not occur
within the first 12 months of illness so it’s important to intervene as soon as possible with weight
restoration to restore regular menstrual cycles.
The longer you remain underweight the higher your risk of developing osteoporosis. Alcohol
and cigarettes increase that risk. Patients who lose their periods before they reach 18 also tend
to develop more severe bone loss.
The most common sites of fractures are wrists, hips and spine.
The gold standard to diagnose osteoporosis is a DEXA scan. You should ask your doctor to
organise a scan if you have not had a menstrual cycle for a year or more. If you are taking the
oral contraceptive pill the breakthrough bleeds you experience do not protect the bones and
you should still have a scan if you have been diagnosed with anorexia for over a year. The scan
takes just 30 minutes and involves only 10% of the radiation you’d expect from a chest X-ray.
There are no injections!
If the scan shows that you have some bone loss you should have follow up scans every 2 years
to monitor the density of your bones. The sooner you regain weight and restore a regular
menstrual cycle the higher your chance of your bones fully recovering. However prolonged
periods of being underweight can put you at risk of permanent bone loss.
Treatment
Hormone replacement: Traditional well proven therapies for post-menopausal osteoporosis are
not as effective against osteoporosis in anorexia. Unlike in the menopause simply adding in sex
hormones such as oestrogen doesn’t protect the bones in the same way. It seems that the
mechanisms behind osteoporosis in anorexia are somewhat different. The lost hormones are
only one piece of the jigsaw. Adequate nutrition is essential. The only safe and effective
treatment for osteoporosis is weight restoration.
Though the evidence for using oestrogens is not robust there are some circumstances where
they may be prescribed, either as the oral contraceptive pill or a patch. They should not be
prescribed in children, adolescents, or young people who have yet to achieve their full adult
height, as they can prevent achievement of full adult height. All contraceptive pills carry some
risks such as venous thromboembolism. Some of the injectable contraceptive preparations can
make osteoporosis worse and should not be used in those at risk of bone loss.
Vitamin D: Vitamin D is essential for healthy bones. It is a fat soluble vitamin and people who
eat low fat diets are at risk of vitamin deficiency. Your body can also make Vit D from
sunshine on your skin. It is good advice for anyone with an eating disorder to get Vit D
levels checked and topped up if there is a deficiency, usually with a chewable tablet.
Calcium: Calcium is also essential for bone health. Calcium rich foods include dairy products
(including low fat products) and some orange juice and cereals have added calcium. For those
at risk of poor bone health, supplementing calcium and Vit D levels with a chewable
tablet may be advised.
Bisphosphonates: There is good evidence for using this medication for osteoporosis in
menopause but not yet good evidence in anorexia. It is prescribed by specialists only. It can
stay in the bones for some years and is generally not recommended for women of child bearing
age as it may cause foetal abnormalities in future pregnancies. It may have a place in men and
older women.
Exercise: The evidence is mixed. We know that in people of healthy weight, physical activity
increases bone density. E.g. tennis players have higher bone density in their dominant arm. It is
likely that in anorexia the weight loss from the exercise offsets any benefit. Certainly strenuous
exercise is detrimental to bone density in anorexia.
The hormones, vitamins and minerals are all small pieces of the jigsaw in protecting your
bones, but weight restoration is overwhelmingly the biggest piece. Food is the primary medicine
for osteoporosis in anorexia!
Vincent Sq Clinic J Arkell 02/08/2010
Vincent Sq Clinic F Connan 06/08/2014
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