Differential Diagnosis

The patient presents with weight concerns, poor appetite, and a request for prescription pills for weight gain. The following differential diagnosis is organized into categories:

• Single most likely diagnosis:
  • Anorexia Nervosa: The patient's low BMI (15.6), poor appetite, and eating pattern of only two meals a day without snacks suggest a restrictive eating disorder. The patient's concern about weight and request for weight gain medication also align with the diagnosis of anorexia nervosa.
• Other Likely diagnoses:
  • Avoidant/Restrictive Food Intake Disorder (ARFID): The patient's long-standing poor appetite and restrictive eating pattern could also be indicative of ARFID, although the concern about weight is more typical of anorexia nervosa.
  • Nicotine dependence: The patient's history of vaping and relapse after cessation attempts suggests nicotine dependence, which could contribute to the patient's poor appetite.
  • Depression: Although the patient denies persistent low mood and anhedonia, some days of low mood could be indicative of a depressive disorder, which is often associated with changes in appetite and weight.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Hypothyroidism: Although the patient's periods are regular, hypothyroidism can cause weight loss, poor appetite, and fatigue. It is essential to rule out this condition due to its potential severity and treatability.
  • Diabetes: Uncontrolled diabetes can lead to weight loss and poor appetite. Although the patient's symptoms do not strongly suggest diabetes, it is crucial to consider this diagnosis due to its potential severity.
  • Malabsorption: Conditions like celiac disease or Crohn's disease can cause malabsorption, leading to weight loss and poor appetite. Although the patient's history does not strongly suggest malabsorption, it is essential to consider this diagnosis.
• Rare diagnoses:
  • Hyperthyroidism: Although less likely, hyperthyroidism can cause weight loss and poor appetite. However, the patient's stable weight and lack of other symptoms like tremors or palpitations make this diagnosis less likely.
  • Gastrointestinal disorders: Rare conditions like gastroparesis or superior mesenteric artery syndrome can cause poor appetite and weight loss. However, these conditions are less likely given the patient's lack of other symptoms like nausea, vomiting, or abdominal pain.