Anorexia Nervosa vs. Constitutional Thinness

Anorexia nervosa is characterized by the intense fear of gaining weight, a distorted body image, inability to maintain a minimally normal weight and extreme dietary habits that prevent weight gains such as food restriction, excessive exercise or purging behaviors. There are two subtypes of anorexia nervosa known as the restricting type and the bing-eating/purging type. Most individuals associate anorexia with the restricting subtype, which is characterized by the severe limitation of food as the primary means to lose weight. The second subtype is known as binge-eating/purging subtype which is characterized by periods of binging followed by self-induced purging behaviors such as vomiting, diuretic abuse, laxative abuse or excessive exercise. Anorexia nervosa is a clinical diagnosis, like most mental health disorders, meaning that there is no specific laboratory test or imaging study that can confirm the diagnosis. Constitutional thinness is an underweight state with no changes in eating behaviors. Low weight is the only similarity between constitutional thinness and anorexia nervosa however recently a study released out of Europe, showed that blood levels of a thyroid hormone can be used to distinguish the two conditions with high sensitivity and specificity.

Anorexia nervosa: DSM IV vs. DSM V

The DSM IV indicated that in order to diagnose anorexia nervosa, the individual must have a certain body mass index and must also have amenorrhea, the absence of menstrual cycles for at least three months. The most recent version of the DSM, the DSMV, eliminated the cutoff for body mass index and also removed the amenorrhea criteria, making the differentiation between constitutional thinness and anorexia nervosa more difficult to distinguish. Estradiol, a form of estrogen that is released from the ovaries and adrenal glands can be used to differentiate constitutional thinness from anorexia nervosa according to the DSM IV guidelines, but since the elimination of menstruation from the criteria, estradiol does not have clinical use in diagnosing anorexia nervosa. Leptin is a hormone that is produced by fat tissue to signal that the individual is no longer hungry. This satiety hormone, however, comes at a high cost and low availability and although it does have a high sensitivity and high specificity for determining the difference between anorexia nervosa and constitutional thinness, this marker is not frequently used in clinical practice.

Thyroid hormone as a diagnostic tool

Free T3 is one of the thyroid hormones commonly used to diagnose thyroid abnormalities such as hypo- or hyperthyroidism. Researchers from this study discovered that free triiodothyronine (T3) could be used with high sensitivity and high specificity to distinguish between anorexia nervosa and constitutional thinness. Moreover, the test for free T3 levels is cheap, and the results are simple to interpret. It is also widely available. The author of this study concluded that for a young, thin woman, a free T3 level of less than 3.3 pmol/L indicates anorexia nervosa with malnutrition. The authors believe that this blood test alone can diagnose anorexia nervosa, however, therapists and psychiatrists argue that a detailed medical history, dietary history and psychological history are necessary in order to diagnose anorexia nervosa and this blood test can be used in addition to the extensive history.

Seeking treatment for anorexia nervosa

Before choosing a treatment center, make sure they have a comprehensive treatment plan in place. This treatment plan is the backbone of your care and can aid you throughout your recovery process. Although the treatment plans may be similar, each person experiences different emotions and their own versions of highs and lows, triumphs and defeats, loves and losses. Recovering from an eating disorder means more than the obsession with scales, measuring cups, hiding food, constant guilt and baggy clothes. It means learning to appreciate yourself for who you are without obsessing about your body image or food. It means mending broken relationships that have been damaged because of your eating disorder. It means learning to cope with negative emotions associated with past abuse and trauma. Recovery means overcoming your battle with low-self esteem and not listening to the advertisements, fashion magazines and all of the negative media telling you what your body should and shouldn’t look like.