Differential Diagnosis for Fever with Chills and Elevated WBC Count

Single Most Likely Diagnosis

• Urinary Tract Infection (UTI): Given the symptoms of fever with chills and an elevated white blood cell (WBC) count of 12,000, a UTI is a common and likely cause. The body's immune response to a bacterial infection in the urinary tract often presents with these symptoms.

Other Likely Diagnoses

• Pneumonia: This is another common infection that could cause fever, chills, and an elevated WBC count. Pneumonia can be caused by bacteria, viruses, or fungi and is a plausible diagnosis given the symptoms.
• Influenza: Especially during flu season, influenza can cause fever, chills, and an elevated WBC count as the body fights off the viral infection.
• Gastroenteritis: An infection of the intestines and stomach, often caused by bacteria or viruses, can lead to fever, chills, and an elevated WBC count.

Do Not Miss Diagnoses

• Sepsis: Although less common, sepsis is a life-threatening condition that occurs when the body's response to an infection damages its own tissues and organs. It's crucial to identify and treat sepsis promptly, as it can be fatal if missed.
• Meningitis: An infection of the protective membranes covering the brain and spinal cord, meningitis can present with fever, chills, and an elevated WBC count, along with other symptoms like headache and stiff neck.
• Appendicitis: An inflammation of the appendix, which can be life-threatening if it ruptures. Fever, chills, and an elevated WBC count can be part of the presentation, especially if the appendix has ruptured and caused a more widespread infection.

Rare Diagnoses

• Endocarditis: An infection of the inner lining of the heart chambers and valves, endocarditis is less common but can present with fever, chills, and an elevated WBC count among other symptoms.
• Osteomyelitis: A bone infection that can cause fever, chills, and an elevated WBC count. It's less common than other infections but should be considered, especially in patients with a history of trauma or those with compromised immune systems.
• Brucellosis: A zoonotic infection (transmitted from animals to humans) that can cause fever, chills, and an elevated WBC count. It's rare in many parts of the world but should be considered in individuals who work with animals or have recently traveled to areas where the disease is common.