Anorexia Nervosa Workup

Updated: Jun 22, 2023
  • Author: Bettina E Bernstein, DO, DFAACAP, DFAPA; Chief Editor: Caroly Pataki, MD  more...
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Approach Considerations

Because an eating disorder is a clinical diagnosis, no definitive diagnostic tests are available for anorexia nervosa. However, given the multi-organ system effects of starvation, a thorough medical evaluation is warranted. Basic tests include the following:

  • Physical and mental status evaluation

  • Complete blood count (CBC)

  • Metabolic panel

  • Urinalysis

  • Pregnancy test (in females of childbearing age)

Gastrointestinal signs include intestinal dilation from constipation and diminished intestinal motility.

Fecal occult blood may be indicative of esophagitis, gastritis, or repetitive colonic trauma from laxative abuse. Thyroid function tests, prolactin, and serum follicle-stimulating hormone (FSH) levels can differentiate anorexia nervosa from alternative causes of primary amenorrhea



Obtain a CBC with erythrocyte sedimentation rate (ESR). The hemoglobin levels are typically normal, although elevations are observed in states of dehydration. If anemia is observed, it is not due to menstrual blood loss, as these patients are usually amenorrheic. In such cases, further investigation is warranted.

The white blood cell (WBC) count is typically low due to increased margination, and thrombocytopenia is also observed. The leukopenia is not a sign that the patient is at an increased risk for infection.

The ESR is normal in anorexia nervosa. Therefore, elevations should prompt a search for an organic etiology, such as neuropsychiatric involvement including affective disorders, psychosis, cognitive dysfunction, and steroid-induced anorexia nervosa in adolescents with systemic lupus erythematosus (SLE), which may be triggered by steroid-induced changes in weight and body shape. Anorexia nervosa may be a presentation of neuropsychiatric SLE; thus, patients with anorexia nervosa who have joint symptoms, a positive antinuclear antibody, or lymphopenia should be investigated and followed for possible SLE, especially as treatment of the SLE may be associated with recovery from anorexia nervosa. [99]


Blood Chemistries

Results can include the following:

  • Hyponatremia: Reflects excess water intake or the inappropriate secretion of antidiuretic hormone (ADH)

  • Hypokalemia: Results from diuretic or laxative use

  • Hypoglycemia: Results from the lack of glucose precursors in the diet or low glycogen stores; low blood glucose may also be due to impaired insulin clearance

  • Elevated blood urea nitrogen (BUN): Renal function is generally normal except in patients with dehydration, in whom the BUN level may be elevated (also perform a urinalysis)

  • Hypokalemic hypochloremic metabolic alkalosis: Observed with vomiting

  • Acidosis: Observed in cases of laxative abuse

Serum vitamin D and calcium levels may be helpful, especially if osteoporosis is suspected, and should always be obtained if a trial of bisphosphonates is attempted for confirmation of osteoporosis. [47, 100]


Liver Function Studies

Liver function test results are minimally elevated, but levels encountered in patients with active hepatitis are not observed. Albumin and protein levels are usually normal, because although the amount of food intake is restricted, it usually contains high-quality proteins.

A dramatic elevation in cholesterol is observed in cases of starvation and may be secondary to the following: (1) a decrease in triiodothyronine (T3) levels, (2) low cholesterol-binding globulin levels, and (3) leakage of intrahepatic cholesterol.


Imaging Studies

A chest radiograph may reveal rib fractures or pneumomediastinum in the presence of other examination and laboratory findings to suggest repetitive vomiting. Patients may also show evidence of osteopenia.

Radiographic evidence of emphysematous changes may be present on chest computed tomography (CT) scans of patients with anorexia nervosa [101] ; however, these changes resolve with refeeding and weight normalization, unlike those seen in chronic obstructive pulmonary disease. Echocardiography can reveal a decreased ventricular mass and mitral valve prolapse.



Cardiovascular complications account for most of the morbidity and mortality associated with anorexia nervosa. Electrocardiography (ECG) can reveal evidence of sinus bradycardia, ST-segment elevation, T-wave flattening, low voltage, and rightward QRS axis, although these changes are clinically insignificant. A finding of QT-interval prolongation, however, may indicate that the patient is at risk for cardiac arrhythmias and sudden death. [102, 78, 1]


Other Tests

The use of scales such as the MacArthur Competence Assessment Tool for Treatment (MacCAT-T) can be helpful in the assessment of mental capacity to refuse treatment. [103]