What is the significance of a rising white blood cell (WBC) count of 14.35 in a patient with recent cholecystectomy and pubic fracture, without fever or signs of infection, and a history of Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) with chronic hyponatremia?

Differential Diagnosis for Rising WBC in a Post-Cholecystectomy Patient

Single Most Likely Diagnosis

• Post-surgical stress response: The patient's recent cholecystectomy and pubic fracture can cause a stress response, leading to an elevated WBC count, particularly neutrophils. The absence of fever and signs of infection supports this diagnosis.

Other Likely Diagnoses

• Reaction to blood transfusion: If the patient received a blood transfusion during or after surgery, it could cause an increase in WBC count, especially if there was an immune response to the transfused blood.
• Pain or stress-induced demargination of neutrophils: Severe pain or stress from the recent surgery and fracture can cause demargination of neutrophils, leading to an elevated WBC count.
• Hypovolemia or dehydration: Although not explicitly stated, hypovolemia or dehydration could contribute to a stress response, elevating the WBC count.

Do Not Miss Diagnoses

• Sepsis: Although the patient does not have fever or signs of infection, sepsis can present atypically, especially in patients with a history of SIADH or those who are elderly. It is crucial to consider sepsis as a potential cause of elevated WBC, even if it seems unlikely.
• Bleeding or hemorrhage: The patient's recent surgery and fracture increase the risk of bleeding or hemorrhage, which could lead to a stress response and elevated WBC count.
• Pulmonary embolism: Given the patient's recent surgery and immobility, pulmonary embolism is a potential risk, and an elevated WBC count could be an indirect sign.

Rare Diagnoses

• Leukemoid reaction: A rare condition characterized by a marked increase in WBC count, often in response to severe infection, inflammation, or other stressors. This diagnosis would require further evaluation, including a bone marrow biopsy.
• Myeloproliferative neoplasm: A group of disorders characterized by the overproduction of blood cells, including WBCs. This diagnosis would be unlikely but should be considered if other causes are ruled out and the patient has a persistent elevation in WBC count.
• Adrenal insufficiency: Although less likely, adrenal insufficiency could contribute to an elevated WBC count, particularly if the patient has a history of chronic illness or is taking corticosteroids.