Differential Diagnosis for 72-year-old Female Patient
The patient presents with a complex medical history and acute symptoms of chills, fever, headache, and fatigue. Given her past medical history and the absence of specific symptoms like cough, rhinorrhea, or urinary symptoms, the differential diagnosis can be organized as follows:
- Single Most Likely Diagnosis
- Viral infection (e.g., influenza or another viral illness): This is considered the most likely due to the abrupt onset of fever, chills, headache, and fatigue, which are common symptoms of viral infections. The absence of respiratory or gastrointestinal symptoms does not rule out a viral etiology, as many viruses can present with systemic symptoms alone.
- Other Likely Diagnoses
- Bacterial infection (e.g., bacteremia or sepsis): Although less likely given the lack of specific symptoms pointing towards a source of infection, the patient's age and comorbid conditions increase her risk for bacterial infections.
- Medication-induced fever: Given her extensive medical history and likely polypharmacy, a drug-induced fever should be considered, especially if she has recently started new medications.
- Do Not Miss Diagnoses
- Endocarditis: Despite the absence of specific cardiac symptoms, her history of A-fib increases her risk for endocarditis, which can present subtly, especially in the elderly.
- Sepsis: Although the patient does not have clear signs of sepsis, her age, fever, and comorbid conditions necessitate consideration of this potentially life-threatening condition.
- Thyrotoxic crisis: Given her history of hyperthyroidism, any acute illness can precipitate a thyrotoxic crisis, which is a medical emergency.
- Rare Diagnoses
- Temporal arteritis: This condition, more common in the elderly, can present with fever, headache, and fatigue, although it typically includes symptoms like jaw claudication or visual disturbances, which are not mentioned.
- Connective tissue disease flare: Although less likely, a flare of an underlying connective tissue disease (if present) could explain her symptoms, but this would be more likely if she had a known history of such a condition.
Each of these diagnoses should be considered in the context of her full medical history, physical examination, and appropriate diagnostic testing to determine the underlying cause of her symptoms.