Differential Diagnosis

The patient's presentation with elevated WBC, RBCs, hemoglobin (H), hematocrit (H), absolute neutrophils, lymphocytes, and monocytes suggests a range of potential diagnoses. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Chronic Myeloid Leukemia (CML) or other myeloproliferative neoplasms: These conditions are characterized by the overproduction of mature and immature cells in the bone marrow, leading to elevated counts of various blood cell types. CML, in particular, often presents with elevated WBC, including neutrophils, and can also affect RBC and platelet counts.

• Other Likely Diagnoses

  • Reactive Leukocytosis: This is a non-specific response to infection, inflammation, or other stressors, leading to an increase in WBCs, including neutrophils and possibly lymphocytes.
  • Polycythemia Vera: Another myeloproliferative neoplasm that primarily affects RBC production but can also increase WBC and platelet counts.
  • Infection: Certain infections, especially those involving the bone marrow or severe systemic infections, can cause a significant increase in WBCs, including neutrophils and lymphocytes.

• Do Not Miss Diagnoses

  • Acute Leukemia: Although less likely than CML given the absence of specific symptoms like blasts in the peripheral blood, acute leukemia (AML or ALL) is a critical diagnosis not to miss due to its aggressive nature and need for immediate treatment.
  • Sepsis: In cases where infection is suspected, sepsis is a potentially life-threatening condition that requires prompt recognition and treatment.

• Rare Diagnoses

  • Primary Myelofibrosis: A myeloproliferative neoplasm characterized by the replacement of bone marrow with fibrotic tissue, leading to abnormal blood cell production. It can present with elevated WBCs but is less common.
  • Essential Thrombocythemia: Another myeloproliferative neoplasm primarily affecting platelet production but can also impact WBC counts.

ICD Code for Follow-Up CBC

To order a follow-up CBC, an appropriate ICD-10 code might be D75.1 (Primary thrombocytosis) if considering myeloproliferative neoplasms, or R71.0 (Elevated white blood cell count) for a more general approach, depending on the suspected underlying diagnosis and the specific guidelines of your healthcare system. However, the choice of ICD code should reflect the most likely diagnosis or the reason for the follow-up testing, which may require further evaluation and specification based on additional clinical information and diagnostic findings.