Polycythemia, secondary

This code signifies an increase in red blood cell mass that is not due to a primary bone marrow disorder. Secondary polycythemia is typically a physiological response to chronic hypoxemia or can be caused by certain tumors producing erythropoietin. It is distinct from polycythemia vera, which is a myeloproliferative neoplasm.

Apply this code when documentation indicates an elevated red blood cell count, hemoglobin, or hematocrit, and the underlying cause is identified as a secondary condition such as chronic obstructive pulmonary disease (COPD), high altitude living, sleep apnea, or erythropoietin-secreting tumors. Supporting documentation should clearly state "secondary polycythemia" or provide a definitive diagnosis of the underlying cause leading to the erythrocytosis.

• Always code the underlying cause of the secondary polycythemia first, if known and applicable, as the primary diagnosis.
• Differentiate carefully from polycythemia vera (238.4 in ICD-9-CM), which is a primary bone marrow disorder.
• Ensure documentation specifies "secondary" to avoid confusion with unspecified polycythemia (289.81 in ICD-9-CM).