Assessment and Diagnosis of Anorexia Nervosa

wpid-wp-1446803951793.jpgAnorexia nervosa is an eating disorder characterized by excessive weight loss, and irrational fear of gaining weight and distorted body self-perception. Anorexia nervosa usually developes during adolescence and early adulthood.Due to the fear of gaining weight, people with this disorder restrict the amount of food they intake. This restriction of food intake causes metabolic and hormonal disorders.The terms anorexia nervosa and anorexia are often used interchangeably, however anorexia is simply a medical term for lack of appetite. Anorexia nervosa has many complicated implications and may be thought of as a lifelong illness that may never be truly cured, but only managed over time. Anorexia nervosa is characterized by low body weight, inappropriate eating and obsession with thin figure.

Anorexia nervosa is often coupled with a distorted self image which may be maintained by various cognitive biases that alter how the affected individual evaluates and thinks about her or his body, food and eating. Persons with anorexia nervosa continue to feel hunger, but deny themselves all but very small quantities of food. The average caloric intake of a person with anorexia nervosa is 600–800 calories per day, but extreme cases of complete self-starvation are known.It is a serious mental illness with a high incidence of comorbidity and similarly high mortality rates to serious psychiatric disorders.[7]

Anorexia most often has its onset in adolescence and is most prevalent among adolescent girls. However, more recent studies show that the onset age of anorexia has decreased from an average of 13 to 17 years of age to 9 to 12. While it can affect men and women of any age, race, and socioeconomic and cultural background,Anorexia nervosa occurs in females 10 times more than in males. While anorexia nervosa is quite commonly (in lay circles) believed to be a woman ‘s illness, it should not be forgotten than ten per cent of people with anorexia nervosa are male.

The term anorexia nervosa was established in 1873 by Sir William Gull, one of Queen Victoria’s personal physicians.The term is of Greek origin: an- (ἀν-, prefix denoting negation) and orexis (ὄρεξις, “appetite”), thus meaning a lack of desire to eat.However, while the term “anorexia nervosa” literally means “neurotic loss of appetite” the literal meaning of the term is somewhat misleading. Many anorexics do enjoy eating and have certainly not lost their appetite as the term “loss of appetite” is normally understood; it is better to regard anorexia nervosa as a self-punitive addiction to fasting, rather than a literal loss of appetite.

Studies have hypothesized that the continuance of disordered eating patterns may be epiphenomena of starvation. The results of the Minnesota Starvation Experiment showed that normal controls exhibit many of the behavioral patterns of anorexia nervosa when subjected to starvation. This may be due to the numerous changes in the neuroendocrine system, which results in a self perpetuating cycle. Studies have suggested that the initial weight loss such as dieting may be the triggering factor in developing AN in some cases, possibly because of an already inherent predisposition toward AN. One study reports cases of AN resulting from unintended weight loss that resulted from varied causes such as a parasitic infection, medication side effects, and surgery. The weight loss itself was the triggering factor



The initial diagnosis should be made by a competent medical professional. There are multiple medical conditions, such as viral or bacterial infections, hormonal imbalances, neurodegenerative diseases and brain tumors which may mimic psychiatric disorders including anorexia nervosa. According to an in depth study conducted by psychiatrist Richard Hall as published in the Archives of General Psychiatry:

  • Medical illness often presents with psychiatric symptoms.
  • It is difficult to distinguish physical disorders from functional psychiatric disorders on the basis of psychiatric symptoms alone.
  • Detailed physical examination and laboratory screening are indicated as a routine procedure in the initial evaluation of psychiatric patients.
  • Most patients are unaware of the medical illness that is causative of their psychiatric symptoms.
  • The conditions of patients with medically induced symptoms are often initially misdiagnosed as a functional psychosis.
  • Complete Blood Count (CBC): a test of the white blood cells. red blood cells and platelets used to assess the presence of various disorders such as leukocytosis, leukopenia, thrombocytosis and anemia which may result from malnutrition.
  • urinalysis: a variety of tests performed on the urine used in the diagnosis of medical disorders, to test for substance abuse, and as an indicator of overall health
  • ELISA: Various subtypes of ELISA used to test for antibodies to various viruses and bacteria such as Borrelia burgdoferi (Lyme Disease)
  • Western Blot Analysis: Used to confirm the preliminary results of the ELISA
  • Chem-20: Chem-20 also known as SMA-20 a group of twenty separate chemical tests performed on blood serum. Tests include cholesterol, protein and electrolytes such as potassium, chlorine and sodium and tests specific to liver and kidney function.
  • glucose tolerance test: Oral glucose tolerance test (OGTT) used to assess the body’s ability to metabolize glucose. Can be useful in detecting various disorders such as diabetes, an insulinoma, Cushing’s Syndrome, hypoglycemia and polycystic ovary syndrome
  • Secritin-CCK Test: Used to assess function of pancreas and gall bladder
  • Serum cholinesterase test: a test of liver enzymes (acetylcholinesterase and pseudocholinesterase) useful as a test of liver function and to assess the effects of malnutrition
  • Liver Function Test: A series of tests used to assess liver function some of the tests are also used in the assessment of malnutrition, protein deficiency, kidney function, bleeding disorders, Crohn’s Disease
  • Lh response to GnRH: Luteinizing hormone (Lh) response to gonadotropin-releasing hormone (GnRH): Tests the pituitary glands’ response to GnRh a hormone produced in the hypothalumus. Central hypogonadism is often seen in anorexia nervosa cases.
  • Creatine Kinase Test (CK-Test): measures the circulating blood levels of creatine kinase an enzyme found in the heart (CK-MB), brain (CK-BB) and skeletal muscle (CK-MM).
  • Blood urea nitrogen (BUN) test: urea nitrogen is the byproduct of protein metabolism first formed in the liver then removed from the body by the kidneys. The BUN test is used primarily to test kidney function. A low BUN level may indicate the effects of malnutrition.
  • BUN-to-creatinine ratio: A BUN to creatinine ratio is used to predict various conditions. High BUN/creatinine ratio can occur in severe hydration, acute kidney failure, congestive heart failure, intestinal bleeding. A low BUN/creatinine can indicate a low protein diet, celiac disease rhabdomyolysis, cirrhosis of the liver
  • echocardiogram: utilizes ultrasound to create a moving picture of the heart to assess function
  • electrocardiogram (EKG or ECG): measures electrical activity of heart can be used to detect various disorders such as hyperkalemia
  • electroencephalogram (EEG): measures the electrical activity of the brain. Can be used to detect abnormalities such as those associated with pituitary tumors
  • Upper GI Series: test used to assess gastrointestinal problems of the middle and upper intestinal tract
  • Thyroid Screen TSH, t4, t3 :test used to assess thyroid functioning by checking levels of thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3)
  • Parathyroid hormone (PTH) test: tests the functioning of the parathyroid by measuring the amount of (PTH) in the blood. Test is used to diagnose parahypothyroidism. PTH also controls the levels of calcium and phosphorus in the blood (homeostasis).
  • barium enema: an x-ray examination of the lower gastrointestinal tract
  • neuroimaging; via the use of various techniques such as PET scan, fMRI, MRI and SPECT imaging should be included in the diagnostic procedure for any eating disorder to detect cases in which a lesion, tumor or other organic condition has been either the sole causative or contributory factor in an eating disorder.


Not only does starvation result in physical complications, but mental complications as well . It has been shown that eating disorders such as anorexia nervosa are reinforced by reward and attention. P.Sodersten and colleagues suggests that effective treatment of this disorder depends on re-establishing reinforcement for normal eating behaviours instead of unhealthy weight loss.

Anorexia nervosa is classified as an Axis Idisorder in the Diagnostic and Statistical Manual of Mental Health Disorders (DSM-IV), published by the American Psychiatric Association. The DSM-IV should not be used by laypersons to diagnose themselves.

  • DSM-IV-TR: diagnostic criteria for AN includes intense fear of gaining weight, a refusal to maintain body weight above 85% of the expected weight for a given age and height, and three consecutive missed periods and either refusal to admit the seriousness of the weight loss, or undue influence of shape or weight on one’s self image, or a disturbed experience in one’s shape or weight. There are two types: the binge-eating/purging type is characterized by overeating or purging, and the restricting type is not.
    • Criticism of DSM-IV There has been criticisms over various aspects of the diagnostic criteria utilized for anorexia nervosa in the DSM-IV. Including the requirement of maintaining a body weight below 85% of the expected weight and the requirement of amenorrhea for diagnosis; some women have all the symptoms of AN and continue to menstruate.Those who do not meet these criteria are usually classified as eating disorder not otherwise specified this may affect treatment options and insurance reimbursments.The validity of the AN subtype classification has also been questioned because of the considerable diagnostic overlap between the binge eating/ purging type and the restricting type and the propensity of the patient to switch between the two
  • Criticisms of DSM-IV and Diagnosing Adolescents with Anorexia Nervosa– There have been criticisms over the diagnostic criteria utilized for anorexia nervosa in the DSM- IV and it’s applicability in diagnosing adolescents with anorexia nervosa. Several criticisms of the DSM-IV in diagnosing adolescents with anorexia nervosa are:
  • Fulfillment of DSM- IV criteria B and C for anorexia nervosa are dependent on complex abstract reasoning, the capacity to describe internal experiences, and the ability to perceive risk. While formal thought emerges between ages 11–13, complex abstract reasoning continues to develop late into adolescence. The ability to perceive risk also continues to develop through adolescence, as some preadolescents have difficult perceiving the relative risk of alternative outcomes. Adolescents and children must first develop these internal thought processes in order to then endorse fear of weight gain or distortion of body image, and deny the seriousness of low body weight despite their behaviors that contribute to harmful weight loss, which are necessary to fulfill criterion B and C.  These developmental factors may impede an adolescent or child from receiving a diagnosis of anorexia nervosa. It is the hope of certain professionals that the DSM- V will take the unique developmental stages of children and adolescents into account when revising the current criteria. One proposed amendment would be to allow behavioral indicators as a means of substituting internally referenced cognitive criteria.
  • Another criticism focuses on the current weight criteria specified to receive a diagnosis of anorexia nervosa. Critics state that there is wide variability in the rate, timing and magnitude of both height and weight gain during normal puberty.Physical development varies greatly during puberty, making it a challenge to define an optimal weight range for a growing child or adolescents.
  • ICD-10: The criteria are similar, but in addition, specifically mention:
  1. The ways that individuals might induce weight-loss or maintain low body weight (avoiding fattening foods, self-induced vomiting, self-induced purging, excessive exercise, excessive use of appetite suppressants or diuretics).
  2. If onset is before puberty, that development is delayed or arrested.
  3. Certain physiological features, including “widespread endocrine disorder involving hypothalamic-pituitary-gonadal axis is manifest in women as amenorrhoea and in men as loss of sexual interest and potency. There may also be elevated levels of growth hormones, raised cortisol levels, changes in the peripheral metabolism of thyroid hormone and abnormalities of insulin secretion”.

Dr. Hilde Burch, in her 1973 book, Eating Disorders: Obesity, Anorexia Nervosa, and the Person Within, explains that Anorexia Nervosa is “not a static condition,” but one that continually provokes new problems with its various stages. She writes, “The state of starvation is associated by marked psychological changes… camouflaged by rationalizations.” She identifies the family interaction becomes difficult, marked by rising anxiety, annoyance and resentment. It also brings about social isolation. (Burch 215).

Dr. Burch believed that anorexia, which is simply not eating enough, as a result from schizophrenia, depression, or esophageal problems often were misdiagnosed as anorexia nervosa. In her assessment, this blurred the definition of anorexia nervosa. For this reason, she distinguished between, what she calls “atypical” and “primary” cases of anorexia nervosa. The atypical cases of anorexia were brought about by a range of stimuli (from schizophrenia to depression, as noted above).

In contrast to the atypical group, Burch observed primary, or genuine anorexia nervosa, “amazingly uniform”. The first outstanding symptom is “disturbance of delusional proportions in the body image”. The second outstanding characteristic is “disturbance in the accuracy of their perception or cognitive interpretation of stimuli arising from the body… failure to recognize hunger and denial of fatigue”. The third outstanding characteristic is a “paralyzing sense of ineffectiveness”. “Anorexics struggle against a feeling of enslaved, exploited, and not being permitted to lead a life of their own. They would rather starve than continue a life of accommodation. In this blind search for a sense of identity and selfhood they will not accept anything that their parents, or the world around them, has to offer.” It is a “desperate struggle for a self respecting identity”. She understood that the personality disorder (struggle for control, for a sense of identity, competence, and effectiveness) precedes the somatic disorders (such as emaciation, amenorrhea, constipation, etc.) (Burch 250–255).

Differential diagnoses

There are various medical and psychological conditions that have been misdiagnosed as anorexia nervosa, in some cases the correct diagnosis was not made for more than ten years. In a reported case of achalasia misdiagnosed as AN, the patient spent two months confined to a psychiatric hospital.

There are various other psychological issues that may factor into anorexia nervosa, some fulfill the criteria for a separate Axis I diagnosis or a personality disorder which is coded Axis II and thus are considered comorbid to the diagnosed eating disorder. Axis II disorders are subtyped into 3 “clusters”, A, B and C.The causality between personality disorders and eating disorders has yet to be fully established. Some people have a previous disorder which may increase their vulnerability to developing an eating disorder. Some develop them afterwards.The severity and type of eating disorder symptoms have been shown to affect comorbidity.

Comorbid Disorders

Axis I Axis II
depression obsessive compulsive personality disorder
substance abuse, alcoholism borderline personality disorder
anxiety disorders narcissistic personality disorder
obsessive compulsive disorder histrionic personality disorder
Attention-Deficit-Hyperactivity-Disorder avoidant personality disorder
  • Body dysmorphic disorder (BDD) is listed as a somatoform disorder that affects up to 2% of the population. BDD is characterized by excessive rumination over an actual or perceived physical flaw. BDD has been diagnosed equally among men and women. While BDD has been misdiagnosed as anorexia nervosa, it also occurs comorbidly in 25% to 39% of AN cases.

BDD is a chronic and debilitating condition which may lead to social isolation, major depression, suicidal ideation and attempts. Neuroimaging studies to measure response to facial recognition have shown activity predominately in the left hemisphere in the left lateral prefrontal cortex, lateral temporal lobe and left parietal lobe showing hemispheric imbalance in information processing. There is a reported case of the development of BDD in a 21 year old male following an inflammatory brain process. Neuroimaging showed the presence of new atrophy in the frontotemporal region.

The distinction between the diagnoses of anorexia nervosa, bulimia nervosa and eating disorder not otherwise specified (EDNOS) is often difficult to make as there is considerable overlap between patients diagnosed with these conditions. Seemingly minor changes in a patient’s overall behavior or attitude can change a diagnosis from “anorexia: binge-eating type” to bulimia nervosa. It is not unusual for a person with an eating disorder to “move through” various diagnoses as his or her behavior and beliefs change over time




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