Essential (hemorrhagic) thrombocythemia

This code identifies a chronic myeloproliferative neoplasm characterized by the overproduction of platelets in the bone marrow, leading to persistently elevated platelet counts. It is considered an essential or primary thrombocythemia, meaning the cause is intrinsic to the bone marrow rather than secondary to another condition. Patients may experience hemorrhagic or thrombotic events due to the abnormal platelet function.

Use this code when documentation clearly specifies "essential thrombocythemia" or "primary thrombocythemia." This diagnosis is typically made after excluding other causes of elevated platelet counts, such as inflammation, infection, or iron deficiency. Supporting documentation should include elevated platelet counts, bone marrow biopsy findings, and molecular testing (e.g., JAK2, CALR, MPL mutations).

• Differentiate carefully from secondary or reactive thrombocytosis, which are coded to D75.838.
• Avoid using this code if the documentation states "thrombocythemia NOS" or "thrombocytosis NOS," as these default to D75.839.
• Ensure the provider's documentation specifies "essential" or "primary" to justify the use of this specific code.