First Menstruation in very young eating disorder patients

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I just reviewed an article which should help us answer the question: how much will my young daughter with anorexia nervosa need to weigh in order to grow normally again and to get a period?

First a few jargon words to know:

Menarche = the first menstrual period
Amenorrhea = no menstrual periods
Primary amenorrhea = never had a menstrual period
Premenarcheal = before menarche
Linear growth = growth in height

Ingemar Swenne of the Uppsala University Children’s Hospital published an article in the 2008 journal Hormone Research. To my reading the article looked carefully done with results relevant to young girls with anorexia nervosa. For that reason I decided to review the salient points for among our readership who may be interested in the subject.

To begin with, they studied only primary amenorrhea in young eating disordered girls, that is, girls who have not ever had a menstrual period. The question was: how much weight gain was required to resume a normal growth rate and then begin to menstruate? How could clinicians determine an “ideal weight” towards which to work, given that a young girl who has never had a period will also need to grow taller (and hence heavier).

Dr Swenne pointed out that “adolescent girls who present with an eating disorder before menarche have not only lost weight but are also stunted in growth”. In other words, they showed inadequate weight gain and a reduced rate of linear growth. I believe we can all agree that growth stunting is a bad thing.

Of particular interest was the finding that this slow-down in linear growth and slow-down in weight gain (even when no loss of weight had occurred) preceded the patient coming to an eating disorder clinic by years! In other words, by the time the parents and physician realized that the child was in trouble years had elapsed. And if only weight loss (not just weight gain that never happened) is taken into account, parents can greatly underestimate how malnourished their child is.

The study showed that it is not adequate to restore a child to their highest-ever-weight for the simple fact that, had they not acquired an eating disorder, they would have weighed more. Repeat: it is not sufficient only to regain lost weight. This is an important point for us clinically, as some parents will become nervous if they think we are restoring their daughter to a weight “heavier than she has ever been”.

So how does one determine how much weight a young child needs to gain in order to restore normal growth and development? This Swedish study emphasizes the inadequacy of “standardized targets”, sometimes called statistical “ideal body weights”, calculated from simple formulas related to height or to insurance tables. The researchers found that relying on these “ideal weights” may result in the child never weighing enough, resulting in persisting amenorrhea (no menstruation). This also reflects our clinical experience.

They also made the observation that 36% of the girls, once weight-restored, seemed to need a weight somewhat above the population average to achieve a first period (menarche) and cautioned us not to underestimate the weight gain needed to continue growing. Rather than focusing on picking a single weight number based on statistics, they recommend a return to the normal growth track for the individual child, one they had been growing along for several years before they got sick. This means that we will look at your child’s individual growth record and determine what their normal, pre-eating disorder growth track likely was, and aim for that. Only then will the brain and reproductive system “turn back on” the myriad of hormones (leptin, estrogens, testosterones, growth hormones, and others yet undescribed) needed for menarche, linear growth and bone growth.

In Sweden record keeping is apparently more organized and wide-spread than here in the US, which has allowed Dr. Swenne to look back at every child’s growth curve for height and weight, at least since age 6. While record keeping in the US is more variable, most parents can gather their child’s growth charts from their primary care doctor. Doing this is very important. The eating disorder doctor will also want to know how tall both biological parents are and roughly how much they weigh. A detailed history of weights and heights on both sides of the family may also be necessary.

The take home messages for us as clinicians and parents:

1. Instead of worrying about weight, worry about return of function (such as menstruation)
2. Let your child know you do not know how much they need to weigh, and you also do not care, because weight is less important to you than normal growth and development.
3. Talk privately to the eating disorder team about any misgivings you may feel when your daughter needs to achieve a weight higher than she ever did before. She is growing.
4. To assist us in making the most individualized assessment of weight gain possible for your child, gather all their growth charts, heights and weights and give it to our doctors.