Differential Diagnosis

The patient's presentation with worsening fatigue, dyspnea, and laboratory findings suggestive of hemolytic anemia requires a thorough differential diagnosis. The following categories outline potential diagnoses:

• Single most likely diagnosis
  • Drug-induced hemolytic anemia: The recent initiation of trimethoprim-sulfamethoxazole, a known cause of hemolytic anemia, especially in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, makes this the most likely diagnosis. The patient's symptoms and laboratory findings, including anemia, elevated indirect bilirubin, and lactate dehydrogenase, support this diagnosis.
• Other Likely diagnoses
  • Sickle cell crisis: Although the patient's HIV status and recent medication changes are more suggestive of a drug-induced cause, sickle cell disease could present with similar symptoms, especially if the patient has not been previously diagnosed.
  • Autoimmune hemolytic anemia: This condition, which can be associated with HIV, could also explain the patient's anemia and laboratory findings.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Severe sepsis or septic shock: Although the patient's vital signs do not currently indicate septic shock, the potential for rapid deterioration, especially in an immunocompromised patient, necessitates consideration of this diagnosis.
  • Malaria: Given the patient's anemia and potential for exposure, malaria should be considered, especially if the patient has recently traveled to an endemic area.
• Rare diagnoses
  • Thrombotic thrombocytopenic purpura (TTP): This rare condition, characterized by thrombocytopenia, microangiopathic hemolytic anemia, and renal failure, could present with similar laboratory findings, although it is less likely given the patient's overall clinical picture.
  • Paroxysmal nocturnal hemoglobinuria (PNH): Another rare condition that could cause hemolytic anemia, PNH is less likely but should be considered if other diagnoses are ruled out.