Bones and Anorexia Nervosa: osteopenia/osteoporosis

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As we all know, weakening of bones is one of the most concerning effects of the malnutrition associated with anorexia nervosa (AN) in girls and boys.

What is the problem?

Osteopenia (“weak bones”) is a precursor to osteoporosis (“bones full of holes”). It is not uncommon for a young patient with anorexia nervosa to present to their doctor with a stress fracture as the first manifestation of their illness. And sometimes even that gets ignored.

Many patients (especially boys) come to us with osteoporosis already present. Parents are usually appalled and understandably anxious to be told how this terrible weakening of their child’s bones can be reversed. Can it?

It can, but full reversal takes time. Years. And there is no medication that works but food.

What is the evidence? What should I know?

Today I reviewed an article in the International Journal of Eating Disorders by Philip S. Mehler, M.D. and Thomas D. MacKenzie, M.D., M.S.P.H. from the Department of Medicine at the University of Colorado Health Sciences Center.

They raise several points for you to focus on, and I do mean YOU, dear reader, since most physicians remain uninformed about the treatment of osteoporosis/osteopenia in young patients with eating disorders and continue to treat them with hormones, something that has been known for years not to work.

1. The only treatment for bone loss is adequate weight restoration through adequate and sustained re-feeding and even this will not work if you wait too long.

2. In a female, the bones will not and cannot heal without adequate estrogen, meaning resumption or initiation of menstruation.

3. Hormones (e.g. birth control) will not help and they will mask amenorrhea (lack of true menstruation).

4. If you do not act quickly (before the early-mid twenties) your child’s bones may never heal. There is a window of opportunity that closes. Don’t miss it.

5. Weight bearing exercise does not have the same good effect on the bones of patients with anorexia nervosa that it has on those without. Don’t count on exercise to save the day. To the contrary (see below).

6. If your child’s treatment team has “helped a lot” and your child’s eating disorder is “much better” but she still does not have periods, do NOT accept this; if it goes on your child may become a 28 year old with the bones of a 90 year old.

What treatment works?

In the article “Treatment of Osteopenia and Osteoporosis in Anorexia Nervosa: A Systematic Review of the Literature” in the International Journal of Eating Disorders 2009; 42:195-201 (print it out for your doctor) Drs. Mehler and MacKenzie systematically reviewed the evidence for various treatments of bone loss. In none of the eight studies they looked at were hormones (estrogen) shown to be of any help. The best study showed no evidence of help using bisphosphonates (Boniva, Fosamax, Reclast, etc) either, despite being useful in the treatment of osteoporosis in menopausal women.

And worse, although the use of birth control pills and other hormones has been shown to be useless, the authors found that “this practice [giving hormones] is unfortunately followed 75-80% of the time by practitioners caring for females with AN.” This is not the first study showing hormones to be of no value and if your doctor has prescribed them for your child you need to educate them urgently. I would be concerned that if a provider is not up-to-date- enough to know that this practice is not indicated and may be harmful, they are not very up-to-date on the treatment of anorexia nervosa.

How long does it take to develop a problem?

The authors go on to state: “there is emerging evidence which suggests that the loss of BMD [bone mineral density] appears to be rapid and occurs relatively early in the disease. Some studies suggest an illness duration longer than 6-12 months predicts significant loss of bone mineral. A severe degree of demineralization has been reported even in adolescents with a brief duration of illness.”

Time to act: now.

Can my child literally break their bones?

When looking at the risk of fracture the article reports: “…fracture risk is known to double with each decrease of one standard deviation in BMD.”

Don’t know what “one standard deviation in BMD” is? This is not surprising and why should you? That is your doctor’s job and every doctor who treats young people with AN should be highly familiar with the bone density xray study called a DEXA scan (Dual Energy Xray Absorptiometry). At the Kartini Clinic we do initial DEXA scans on our patients to evaluate their bones and if they are weak, we follow them with a DEXA scan every year.

Because they have been sick (and undiagnosed) for a long time boys in particular often come to us with severe osteopenia or oseoporosis that no one has noticed.

How about exercise? Isn’t exercise good for bones?

The authors’ comments on weight-bearing exercise are important, since some people feel “any exercise is good” and some doctors are reluctant to face the ire of their patients by limiting what they can do. Again, Drs. Mehler and MacKenzie: “Although weight bearing exercise is known to help avert osteoporosis in the general population and is an important contributor to the overall establishment of peak bone mass, there seems to be an inconsistent relationship in AN. Once again in previously cited studies, there was no relationship between amount of physical activity and BMD [bone mineral density]. Weight-bearing exercise may only be protective if menstruation has been preserved. If excessive weight-bearing exercise leads to estrogen deficiency and amenorrhea [lack of periods], it may in fact be deleterious [harmful]…”

So… if your doctor or therapist or nutritionist lets your child run although they have no periods, challenge this. If they then compound the problem by prescribing the birth control pill to “jump-start” her periods, get another doctor. In no other medical field that I am aware of has so much out-of-date care been tolerated by so many.

How fast must we act?

I will leave you with a final conclusion from Drs. Mehler and MacKenzie study (my italics): “low bone density at this time of life [adolescence] causes additional consternation because there may not be enough time for catch-up even if weight recovery does occur, thus placing these patients at risk for irreversible skeletal damage.

I don’t like the sound of irreversible, do you?