Differential Diagnosis for Elevated WBC, Neutrophils, and Lymphocytes

Single Most Likely Diagnosis

• Acute Bacterial Infection: This is often the most common cause of elevated white blood cell (WBC) count, with a predominance of neutrophils, and can also see an increase in lymphocytes as the body mounts an immune response. Examples include pneumonia, urinary tract infections, and skin infections.

Other Likely Diagnoses

• Viral Infections: Certain viral infections, such as influenza, mononucleosis (caused by Epstein-Barr virus), and cytomegalovirus, can cause an increase in both neutrophils and lymphocytes.
• Chronic Inflammatory Conditions: Conditions like rheumatoid arthritis, lupus, and inflammatory bowel disease can lead to a chronic elevation in WBC count, including both neutrophils and lymphocytes, due to ongoing inflammation.
• Medication Effects: Some medications can cause an increase in WBC count, including corticosteroids, lithium, and certain antibiotics.

Do Not Miss Diagnoses

• Sepsis: A life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. Early recognition and treatment are crucial, and an elevated WBC count with a left shift (increase in immature neutrophils) can be a key indicator.
• Hematological Malignancies: Leukemias, such as acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML), can present with elevated WBC counts, including increases in both neutrophils and lymphocytes. These conditions require prompt diagnosis and treatment.
• Severe Trauma or Burns: Significant physical stress can lead to a marked increase in WBC count as part of the body's stress response, including elevations in both neutrophils and lymphocytes.

Rare Diagnoses

• Lymphoproliferative Disorders: Rare conditions like lymphoma or other lymphoproliferative disorders can cause an elevation in lymphocyte count and, in some cases, an increase in neutrophils as well.
• Myeloproliferative Neoplasms: Disorders such as polycythemia vera, essential thrombocytosis, or primary myelofibrosis can lead to an overproduction of blood cells, including neutrophils and, less commonly, lymphocytes.
• Autoimmune Disorders: Certain autoimmune conditions, such as Hashimoto's thyroiditis or type 1 diabetes, can occasionally present with elevated WBC counts, including increases in both neutrophils and lymphocytes, although this is less common.