Differential Diagnosis

The patient presents with a complex set of symptoms including a persistent cough, recent onset of diarrhea, reduced urine output, chest tightness, joint pain, difficulty swallowing, and coughing up large amounts of brown phlegm. Her history of asthma and anemia, along with the increased use of her Ventolin puffer, suggests an exacerbation of her asthma but also raises concerns for other underlying conditions. Here is a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Sarcoidosis: This condition can cause a wide range of symptoms including cough, chest tightness, joint pain, and difficulty swallowing. It can also affect the kidneys, leading to reduced urine output, and can cause anemia. The presence of brown phlegm could indicate pulmonary involvement. Sarcoidosis can also exacerbate asthma symptoms.

• Other Likely Diagnoses

  • Inflammatory Bowel Disease (IBD): Given the diarrhea and the systemic symptoms such as joint pain, IBD (Crohn's disease or ulcerative colitis) should be considered. However, the primary respiratory symptoms might not be fully explained by IBD alone.
  • Connective Tissue Disease (e.g., Rheumatoid Arthritis, Lupus): These conditions can cause joint pain, chest tightness, and systemic symptoms including renal involvement. They might also exacerbate asthma or cause respiratory symptoms.
  • Chronic Obstructive Pulmonary Disease (COPD) Exacerbation: Although less likely in a 28-year-old without a significant smoking history, COPD could explain the respiratory symptoms. However, the systemic symptoms and reduced urine output would be less typical.

• Do Not Miss Diagnoses

  • Pulmonary Embolism: Although less likely given the chronic nature of the symptoms, pulmonary embolism can cause chest tightness and cough. It's a critical diagnosis not to miss due to its high mortality rate if untreated.
  • Tuberculosis (TB): TB can cause a chronic cough, chest tightness, and systemic symptoms including joint pain and anemia. It's particularly important to consider in patients with risk factors for TB exposure.
  • Sepsis: Any patient with systemic symptoms and potential organ dysfunction (reduced urine output) should be evaluated for sepsis, especially if there's a source of infection (e.g., pneumonia).

• Rare Diagnoses

  • Wegener's Granulomatosis (Granulomatosis with Polyangiitis): A rare autoimmune disorder that can affect multiple systems including the lungs, kidneys, and joints, causing a wide range of symptoms similar to those presented.
  • Lymphangioleiomyomatosis (LAM): A rare lung disease that primarily affects women, causing respiratory symptoms, but it can also involve the kidneys and cause other systemic symptoms.
  • Eosinophilic Granulomatosis with Polyangiitis (Churg-Strauss Syndrome): A rare condition that can cause asthma, eosinophilia, and systemic vasculitis affecting multiple organs, including the lungs, kidneys, and joints.