Differential Diagnosis for WBC 20 with Low Grade Fever

Single Most Likely Diagnosis

• Viral infection: A low grade fever and elevated white blood cell count (WBC) of 20 can be indicative of a viral infection, which is a common and often self-limiting condition. The body's immune response to a viral infection can cause an increase in WBCs as it fights off the invading virus.

Other Likely Diagnoses

• Bacterial infection: Although the fever is low grade, a bacterial infection could still be the cause, especially if the WBC count is significantly elevated. Bacterial infections can range from mild to severe and require appropriate antibiotic treatment.
• Inflammatory condition: Conditions such as rheumatoid arthritis, lupus, or other autoimmune diseases can cause an elevated WBC count along with low-grade fever due to the body's inflammatory response.
• Reaction to medication: Certain medications can cause an increase in WBC count as a side effect, and if accompanied by a low-grade fever, could be considered in the differential diagnosis.

Do Not Miss Diagnoses

• Septicemia: Although less likely with a low-grade fever, septicemia (blood infection) is a potentially life-threatening condition that requires immediate attention. An elevated WBC count can be an indicator of the body's response to a severe infection.
• Neutropenic fever: If the patient is neutropenic (has a low neutrophil count), even a low-grade fever can be a sign of a serious infection that requires prompt treatment.
• Malignancy: Certain types of cancer, such as leukemia or lymphoma, can present with elevated WBC counts and low-grade fevers. These conditions are critical to diagnose early for effective treatment.

Rare Diagnoses

• Lymphoma: While mentioned in the "Do Not Miss" category due to its severity, lymphoma is relatively rare and would be considered less likely without other supporting symptoms or findings.
• Leukemia: Similar to lymphoma, leukemia is a rare condition that can cause an elevated WBC count but would require additional diagnostic evidence for confirmation.
• Other hematologic disorders: Rare blood disorders can also lead to elevated WBC counts and may present with low-grade fever, though they are less common and would typically be diagnosed through more specific tests and evaluations.