Workup for Lack of Appetite
The initial workup for anorexia (loss of appetite) must begin with screening for eating disorders, followed by a comprehensive assessment of weight history, eating behaviors, vital signs with orthostatic measurements, and targeted laboratory testing including CBC, comprehensive metabolic panel, and ECG when indicated.
Initial Clinical Assessment
Weight and Vital Sign Evaluation
- Measure current weight, height, and BMI (or BMI percentile/Z-score for children and adolescents), and obtain maximum and minimum weight history with recent weight changes 1
- Assess vital signs including temperature, resting heart rate, blood pressure, orthostatic pulse, and orthostatic blood pressure to identify cardiovascular instability 1
- Document physical appearance for signs of malnutrition or purging behaviors (e.g., dental erosion, swollen parotid glands, calluses on knuckles) 1
Detailed Eating Behavior History
Systematically assess the following eating patterns 1:
- Presence, patterns, and changes in restrictive eating, food avoidance, binge eating, and other eating-related behaviors (rumination, regurgitation, chewing and spitting)
- Changes in food repertoire including breadth of food variety, narrowing or elimination of food groups
- Compensatory and weight control behaviors: dietary restriction, compulsive or driven exercise, purging behaviors (laxative use, self-induced vomiting), and medication use to manipulate weight
- Percentage of time preoccupied with food, weight, and body shape
- Prior treatment and response to treatment for eating disorders
Psychosocial and Family Assessment
- Identify co-occurring psychiatric disorders including depression, anxiety, and substance abuse, as these are common comorbidities 1
- Assess psychosocial impairment secondary to eating or body image concerns 1
- Obtain family history of eating disorders, other psychiatric illnesses, and medical conditions (obesity, inflammatory bowel disease, diabetes mellitus) 1
Laboratory and Diagnostic Testing
Essential Laboratory Studies
Order the following baseline tests 1:
- Complete blood count (CBC)
- Comprehensive metabolic panel including electrolytes, liver enzymes, and renal function tests
- These tests identify complications such as electrolyte imbalances (particularly hypokalemia from purging), anemia, and organ dysfunction
Electrocardiogram Indications
Obtain an ECG in the following situations 1:
- Patients with restrictive eating disorders
- Patients with severe purging behavior
- Patients taking medications known to prolong QTc intervals
The ECG screens for potentially fatal arrhythmias and QTc prolongation, which can occur with malnutrition and electrolyte disturbances.
Comprehensive Review of Systems
Conduct a thorough review of systems to identify medical complications 1:
- Cardiovascular: bradycardia, hypotension, arrhythmias
- Gastrointestinal: constipation, gastritis, esophagitis, gastric dilation
- Endocrine: amenorrhea, infertility, hypothermia
- Musculoskeletal: osteoporosis risk
- Dermatologic: lanugo hair, dry skin, edema
- Dental: erosion from vomiting
Special Considerations for Cancer Patients
If the patient has cancer or advanced illness, consider additional causes of anorexia 1:
- Cancer-associated anorexia may warrant consideration of corticosteroids (for 1-3 weeks only due to side effects including muscle wasting) or progestins (with awareness of thromboembolism risk) in advanced disease
- Long-chain omega-3 fatty acids or fish oil supplementation may stabilize appetite and body weight in cancer patients undergoing chemotherapy
Critical Red Flags Requiring Immediate Intervention
The following findings mandate urgent or inpatient management 2:
- BMI ≤16.1 kg/m² (associated with higher premature mortality)
- Severe orthostatic hypotension (e.g., systolic BP drop >20 mmHg with significant heart rate increase)
- Rapid weight loss (>15-19% over 3 months)
- Stimulant abuse (e.g., Adderall) in context of eating disorder
- Severe electrolyte abnormalities
- QTc prolongation on ECG
Documentation and Treatment Planning
Document a comprehensive, culturally appropriate, person-centered treatment plan that incorporates medical, psychiatric, psychological, and nutritional expertise, ideally via a coordinated multidisciplinary team 1. This approach is essential because eating disorders require simultaneous attention to medical stabilization, nutritional rehabilitation, and psychiatric treatment to improve morbidity and mortality outcomes.