A mental health professional, such as a psychiatrist, psychologist or social worker, can diagnose anorexia nervosa based on the history reported by the patient and the family. The person with anorexia may not report symptoms reliably, so reports from family members may be necessary to make a diagnosis. Often, a pediatrician or primary care physician is the first to make the diagnosis.
One special problem with this diagnosis is that individuals with the disorder often deny the problem and are reluctant to participate in an evaluation.
The health care professional will ask about the person's attitudes toward weight, food and body image, and he or she will check for lower than normal body weight and the physical signs of starvation, which include:
Low blood pressure
Enlarged salivary glands
Lanugo, a very fine type of body hair
The stopping of periods in a woman
Dental problems, because stomach acids can damage teeth if the person purges regularly
Some clinicians find it helpful to use screening tests. Examples are the Eating Disorders Inventory and the Eating Aptitudes Test.
As part of the evaluation, the clinician may explore whether the person has other problems that need treatment, such as a mood or anxiety disorder, obsessive-compulsive disorder, a personality disorder or substance abuse. It is common for people with anorexia nervosa to have symptoms of depression, including low mood, social withdrawal, irritability, poor sleep and diminished interest in sex. People with the binging/purging type of anorexia nervosa are more likely to have mood ups and downs, have problems with impulse control, and abuse alcohol and drugs.
Medical evaluation includes blood work to investigate whether poor nutrition has caused anemia (low red blood cell count), altered liver and kidney function, and abnormal levels of blood chemicals, such as low potassium.
A doctor also needs to make sure there are no other medical problems that might be causing weight loss, such as inflammatory bowel disease, cancer or hormonal problems. People with those illnesses, however, do not usually have a problem with their body image.