Differential Diagnosis for Unintentional Weight Loss

The patient presents with a 15-pound unintentional weight loss over two months, accompanied by fatigue and decreased appetite. The following differential diagnoses are considered:

• Single Most Likely Diagnosis
  • Depression or Anxiety Disorder: The patient's recent increased work stress, mild anxiety, and good eye contact but lack of other systemic symptoms suggest a possible psychiatric cause for the weight loss. The patient's history of anxiety and the absence of significant physical findings support this diagnosis.
• Other Likely Diagnoses
  • Diabetes Mellitus: Given the patient's history of pre-diabetes, the unintentional weight loss could be an indication of progression to diabetes mellitus. However, the lack of polyuria, polydipsia, or other classic symptoms makes this less likely.
  • Hyperthyroidism: Weight loss, fatigue, and decreased appetite can be symptoms of hyperthyroidism. However, other symptoms such as exophthalmos, tremors, or heat intolerance are not mentioned.
  • Chronic Stress Reaction: The patient's recent increased work stress could lead to a chronic stress reaction, causing weight loss, fatigue, and decreased appetite.
• Do Not Miss Diagnoses
  • Malignancy (e.g., Pancreatic Cancer): Although less likely, malignancy must be considered in cases of unexplained weight loss, especially in the absence of other symptoms. Pancreatic cancer, for example, can present with weight loss, fatigue, and decreased appetite.
  • Infectious Diseases (e.g., HIV, Tuberculosis): These conditions can cause weight loss, fatigue, and decreased appetite. Although the patient denies fever, night sweats, or other systemic symptoms, these diagnoses should not be entirely ruled out without further testing.
  • Gastrointestinal Disorders (e.g., Celiac Disease, Crohn's Disease): Despite the patient denying GI symptoms, certain gastrointestinal disorders can cause weight loss and malabsorption without overt GI symptoms.
• Rare Diagnoses
  • Addison's Disease: This rare endocrine disorder can cause weight loss, fatigue, and decreased appetite, among other symptoms. However, other characteristic symptoms such as hyperpigmentation, orthostatic hypotension, or electrolyte imbalances are not mentioned.
  • Pheochromocytoma: Although rare, this tumor of the adrenal gland can cause weight loss, fatigue, and other symptoms due to excessive catecholamine production. However, typical symptoms such as hypertension, palpitations, or sweating are not present in this case.