What medical data supports a diagnosis of anorexia nervosa?

Medical Data Supporting Anorexia Nervosa Diagnosis

A comprehensive diagnosis of anorexia nervosa requires specific medical data including weight status (BMI <18.5 kg/m²), vital sign abnormalities, laboratory findings, and psychological assessment of food/weight preoccupation. 1, 2

Essential Diagnostic Criteria

Physical Assessment Data

• Weight and Body Composition:

  • Weight loss of at least 25% of ideal body weight 3
  • BMI <18.5 kg/m² for adults 2
  • For children/adolescents: percent median BMI, BMI percentile, or BMI Z-score 1
  • Total weight loss and weight status documentation 1

• Vital Signs:

  • Bradycardia (heart rate <40 bpm) 2
  • Hypotension 2
  • Hypothermia 2
  • Orthostatic pulse and blood pressure changes 1

Laboratory Assessment

• Required Laboratory Tests:

  • Complete blood count 1
  • Comprehensive metabolic panel 1
  • Electrolytes (particularly monitoring for hypokalemia, hyponatremia, hypophosphatemia) 2
  • Liver enzymes 1, 2
  • Renal function tests 1
  • Electrocardiogram (especially for QTc interval assessment) 1, 2

• Additional Tests When Indicated:

  • Hormonal workup if oligomenorrhea/amenorrhea present 1
  • 25-hydroxyvitamin D levels 1
  • Thyroid function tests 1, 2
  • Bone density assessment (DXA) if indicated 1, 2

Psychological Assessment

• Eating Behaviors:

  • Documentation of eating patterns and food avoidance behaviors 1
  • Patterns and changes in food repertoire (narrowing or elimination of food groups) 1
  • Percentage of time preoccupied with food, weight, and body shape 1
  • Presence of distorted body image (patient insists they are fat despite being underweight) 3

• Weight Control Behaviors:

  • Documentation of compensatory behaviors: dietary restriction, compulsive exercise, purging 1
  • Frequency and types of purging behaviors (vomiting, laxatives, starvation) 1

Differential Diagnosis Considerations

Medical data must rule out other causes of weight loss:

• Malignancy 4
• Inflammatory bowel disease 4
• Infections 4
• Metabolic disorders 4
• Other psychiatric disorders (depression, anxiety, OCD) 1

Risk Stratification Data

• High-Risk Indicators:
  • BMI <16 kg/m² 1
  • Severe electrolyte abnormalities 2
  • Syncope or seizures 2
  • Significant bradycardia or hypotension 2
  • Longer duration of illness (>10 years) 1
  • Poor social adjustment 1
  • Alcohol abuse 1

Monitoring Parameters

For ongoing assessment and treatment monitoring:

• Weekly weight measurements 2
• Regular vital sign monitoring 2
• Serial ECGs 2
• Regular laboratory testing 2
• Assessment of cognitive function 2
• Gastrointestinal symptom monitoring 2

Important Clinical Considerations

• Normal laboratory results do not exclude serious illness or medical instability in anorexia nervosa 1
• Physiologic changes including amenorrhea are key diagnostic criteria 3
• More than half of children and adolescents with eating disorders may not fully meet all DSM criteria but still experience the same medical consequences 1
• Endocrine alterations are common and may be adaptive, reactive, or etiologic 5
• Careful monitoring during refeeding is essential to prevent refeeding syndrome 2

The diagnosis of anorexia nervosa should be made by a multidisciplinary team that includes medical, psychiatric, psychological, and nutritional expertise 1, with the team physician having the ultimate authority in determining medical stability and safety 1.