Differential Diagnosis for Unintentional Weight Loss

The patient presents with a 2-month history of unintentional weight loss of 15 pounds, accompanied by fatigue and decreased appetite, but without fever, GI symptoms, night sweats, or pain. Given the patient's history and physical examination, the following differential diagnoses are considered:

• Single Most Likely Diagnosis
  • Depression or Anxiety Disorder: The patient's history of anxiety, recent increased work stress, and symptoms of fatigue and decreased appetite without other systemic symptoms suggest a possible exacerbation of anxiety or an underlying depressive disorder. The weight loss and lack of interest in eating can be associated with these conditions.
• Other Likely Diagnoses
  • Pre-diabetic State Progressing to Diabetes: Although the patient's last A1c was 6.2%, which is in the pre-diabetic range, the unintentional weight loss could be an early sign of progression to diabetes, especially if the patient's glucose metabolism has worsened.
  • Hypothyroidism: This condition can cause weight loss, fatigue, and decreased appetite. Although the patient does not report cold intolerance or other classic symptoms, hypothyroidism can sometimes present subtly.
  • Chronic Stress Reaction: The patient's recent increased work stress could be contributing to the weight loss through mechanisms such as increased cortisol levels affecting appetite and metabolism.
• Do Not Miss Diagnoses
  • Cancer (e.g., Pancreatic, Lung, or Gastrointestinal): Although less likely given the lack of other symptoms such as night sweats, fever, or specific pains, cancer must always be considered in the differential diagnosis of unintentional weight loss due to its potential severity and the need for early detection.
  • Infectious Diseases (e.g., HIV, Tuberculosis): These conditions can cause weight loss and fatigue. The absence of fever, night sweats, or other specific symptoms does not rule out these diagnoses entirely, especially in the early stages.
  • Neurological Disorders (e.g., Parkinson's Disease, Dementia): Certain neurological conditions can lead to weight loss due to decreased appetite, difficulty eating, or increased metabolic rate.
• Rare Diagnoses
  • Addison's Disease: A rare endocrine disorder that can cause weight loss, fatigue, and changes in appetite, although it typically presents with other symptoms such as hypotension and hyperpigmentation.
  • Pheochromocytoma: A rare tumor of the adrenal gland that can cause weight loss, among other symptoms like hypertension, palpitations, and sweating, due to excessive catecholamine production.

Each of these diagnoses requires careful consideration of the patient's symptoms, history, and physical examination findings, along with appropriate diagnostic testing to determine the underlying cause of the unintentional weight loss.