ICD-10 Code D45: Polycythemia vera diagnosis and billing guide

Key Takeaways

ICD-10 Code D45 is the billable diagnosis code for polycythemia vera, a myeloproliferative disorder causing overproduction of red blood cells.

D45 falls under Chapter 2 (C00-D49), specifically the D37-D48 neoplasms of uncertain behavior range, and carries a Type 1 Excludes note.

Secondary polycythemia is coded with D75.1, not D45 – conflating the two is a common documentation error that triggers claim denials.

Pabau’s claims management software and structured client records help hematology practices reduce D45 coding errors and streamline reimbursement workflows.

ICD-10 Code D45 is the billable, specific diagnosis code for polycythemia vera (PV), the primary myeloproliferative form of the condition. Assigning it accurately means understanding both the clinical definition and the coding exclusions that separate it from secondary polycythemia (D75.1).

This guide covers D45’s definition, billability, excludes notes, related codes, ICD-9 crosswalk, and documentation requirements for medical coders and clinicians working in hematology and related specialties.

The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS) jointly maintain ICD-10-CM, which classifies D45 under the Neoplasms of uncertain behavior chapter. For FY2026, D45 remains valid and billable without further specificity required.

ICD-10 Code D45: definition and clinical description

ICD-10 Code D45 describes polycythemia vera, a chronic myeloproliferative disorder characterized by abnormal proliferation of all hematopoietic bone marrow elements with an absolute increase in red cell mass and total blood volume. The condition is frequently associated with splenomegaly, leukocytosis, and thrombocythemia.

Polycythemia vera is driven in most cases by a somatic mutation in the JAK2 gene (JAK2 V617F or exon 12), which leads to unregulated growth of erythroid progenitor cells. In ICD-10-CM, D45 sits within the category of neoplasms of uncertain behavior, reflecting that while PV is not frankly malignant, it carries a risk of transformation to myelofibrosis or acute leukemia.

Clinically, patients present with elevated hematocrit, erythrocytosis, and constitutional symptoms including pruritus, headaches, and elevated thrombotic risk. Treatment commonly involves therapeutic phlebotomy and cytoreductive agents such as hydroxyurea, though specific treatment protocols are determined by the treating hematologist.

Code hierarchy for D45

• Chapter: 2 – Neoplasms (C00-D49)
• Block: D37-D48 – Neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes
• Code: D45 – Polycythemia vera
• Billable: Yes (terminal code, no further subdivision required)
• Valid FY2026: Yes

Billability and valid use

D45 is a fully billable ICD-10-CM diagnosis code for FY2026. It requires no additional specificity, meaning coders can submit D45 as the principal or secondary diagnosis without appending a subcategory code. The CDC’s ICD-10-CM web tool confirms D45 as a valid, active code in the current tabular list.

D45 may function as the principal diagnosis when polycythemia vera is the primary reason for the encounter, such as a hematology visit for phlebotomy management. It also appears as a secondary code alongside procedure-specific primary diagnoses when PV is the underlying condition driving a separate coded service.

Known synonyms accepted under D45 include polycythemia rubra vera, chronic erythremia, and erythrocytosis due to polycythemia vera. These clinical terms map to the same code and can appear in documentation without triggering a different code assignment.

Excludes notes and sequencing rules

D45 carries a Type 1 Excludes note. In ICD-10-CM, a Type 1 Excludes (also written “Excludes1”) means “NOT CODED HERE.” The excluded code describes a condition that is mutually exclusive with D45 and must never be reported on the same claim alongside D45.

D45 carries two Type 1 Excludes entries: familial polycythemia (D75.0) and secondary polycythemia (D75.1). Neither may be reported on the same claim as D45. Submitting D45 alongside an excluded code triggers an edit at the payer level, resulting in denial or a request for additional documentation.

Excludes1 vs Excludes2 at a glance

Sequencing D45 as principal vs secondary diagnosis

When the encounter’s primary purpose is managing polycythemia vera (for example, therapeutic phlebotomy or cytoreductive therapy monitoring), D45 is the principal diagnosis. When PV is an underlying condition and the encounter addresses a complication or separate problem, D45 is sequenced as an additional code. The ICD-10-CM Official Guidelines for Coding and Reporting, updated annually by CMS and NCHS, govern sequencing decisions; coders should apply Section I.C.2 (Neoplasm coding) as their authority.

D45 vs D75.1: secondary polycythemia coding distinction

The most clinically significant differentiation in polycythemia coding is between D45 and D75.1 (secondary polycythemia). Getting this wrong does not just cause a denial; it creates a diagnostic record that misrepresents the patient’s condition and can affect downstream treatment decisions.

D45 (polycythemia vera): Primary, autonomous overproduction of red cells due to a clonal bone marrow disorder, typically driven by a JAK2 mutation. Confirmed by bone marrow biopsy and WHO 2016/2022 diagnostic criteria (which include JAK2 mutation, elevated hemoglobin/hematocrit, and bone marrow hypercellularity).

D75.1 (secondary polycythemia): Reactive erythrocytosis caused by an identifiable external stimulus, such as hypoxia from COPD, sleep apnea, or high altitude exposure, renal tumors producing excess erythropoietin, or tobacco use. No JAK2 mutation is typically present.

Coders must rely on the physician’s documented diagnosis. If the documentation states “polycythemia vera” with supporting laboratory evidence, use D45. If it states “secondary polycythemia” or “erythrocytosis secondary to [cause],” use D75.1 and the causative condition as the principal diagnosis. When documentation is ambiguous, query the provider before coding. For related blood-disorder coding, the blood disorder manifestation coding guide and the disseminated intravascular coagulation (D65) guide show how coexisting hematologic conditions are sequenced.

Related and associated codes

Hematology encounters involving D45 rarely stand alone. The following codes frequently appear alongside D45 in the same encounter or in the patient’s chronic problem list.

PV also coexists with other hematologic conditions that carry their own codes. The iron deficiency anemia (D50.0) and acute posthemorrhagic anemia (D62) guides cover sequencing when more than one blood-disorder diagnosis appears on the same claim.

ICD-9-CM to D45 crosswalk

Practices that maintain historical records or work with older claims data need to understand how D45 maps back to its ICD-9-CM equivalents. The transition from ICD-9-CM to ICD-10-CM occurred on October 1, 2015.

Note that ICD-10-CM D45 does not distinguish between active disease, remission, and relapse states, unlike the ICD-9 system. Clinical documentation of remission status is still clinically important but does not change the code assignment to D45 under the current ICD-10-CM structure.

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Documentation requirements for D45

Accurate D45 coding depends on what the physician documents, not what the lab results suggest. ICD-10-CM Official Guidelines state that coders assign codes based on the provider’s established diagnosis. For polycythemia vera, documentation quality determines both code accuracy and reimbursement success.

Minimum documentation elements for D45

• Confirmed diagnosis statement: The provider must explicitly document “polycythemia vera” or a recognized synonym (polycythemia rubra vera, chronic erythremia). “Elevated hematocrit” or “possible PV” is not sufficient.
• WHO diagnostic criteria reference (recommended): Documentation of JAK2 mutation positivity, bone marrow biopsy findings, or hemoglobin/hematocrit above established thresholds strengthens the clinical record and supports medical necessity for associated procedures.
• Comorbidities documented separately: Splenomegaly, thrombocythemia, and leukocytosis should be documented as separate findings if they are being coded and billed as additional diagnoses.
• Treatment plan: Document the management approach (phlebotomy schedule, cytoreductive therapy, or watchful waiting) to support medical necessity for the encounter and any CPT codes reported alongside D45.

Practices using structured client records can build condition-specific templates that prompt providers to include the relevant documentation elements at every hematology encounter. This reduces the back-and-forth that occurs when claims are pended for additional documentation. Pairing this with digital intake forms that capture symptom history and prior treatment responses gives coders a complete picture before they assign D45.

HIPAA requires that all coding and billing activities are grounded in documented clinical information. Maintaining HIPAA-compliant clinical documentation practices protects both the practice and the patient record from audit exposure. For practices handling sensitive chronic disease data, robust patient data security tools should be part of the documentation workflow infrastructure.

Common documentation errors that trigger D45 denials

• Documenting “polycythemia” without specifying “vera” or “primary,” leading coders to default to D75.1
• Failing to document JAK2 status when payers request medical necessity justification for bone marrow biopsy or specialty drugs
• Recording comorbidities (splenomegaly, thrombosis) without a clear causal link statement, making it unclear whether they should be coded as additional diagnoses
• Using “possible” or “probable” polycythemia vera in outpatient documentation (per ICD-10-CM guidelines, uncertain diagnoses are not coded in outpatient settings)

Coders working in dermatology EMR software environments sometimes encounter PV as a secondary diagnosis when patients present with cutaneous manifestations (pruritus, plethora). The same documentation rules apply regardless of the specialty context. PV’s thrombotic complications generate their own diagnoses too; the splenic infarction (D73.5) guide shows how such complications are documented and sequenced alongside D45.

Billing workflow for D45 in hematology practice

A D45 encounter typically generates multiple billable codes. The ICD-10 diagnosis code D45 supports medical necessity for the evaluation and management (E/M) service (CPT 99202-99215 depending on complexity), therapeutic phlebotomy (CPT 99195), and lab panels including CBC with differential. Each of these must be individually supported by the clinical documentation.

CPT codes commonly paired with D45

• 99213-99215: Office or other outpatient visit (E/M for established hematology patient)
• 99195: Phlebotomy, therapeutic
• 85025: Blood count, complete (CBC) with automated differential
• 85046: Reticulocyte count with indices
• 81270: JAK2 gene analysis (V617F variant)
• 38220: Bone marrow aspiration

Practices can use claims management software to build code-pairing rules for D45 encounters, flagging claims that include phlebotomy CPT codes without a supporting D45 or D75.1 diagnosis, and vice versa. This pre-submission validation catches the most common edit failures before they reach the payer.

The AAPC Codify ICD-10-CM lookup provides a useful crosswalk reference for verifying which CPT codes are medically necessary when D45 is the primary diagnosis, including any LCD (Local Coverage Determination) policies that apply to Medicare beneficiaries with polycythemia vera.

For practices managing multiple chronic disease patients, integrating automated workflows into the billing cycle reduces manual handoff errors between the clinical documentation and coding teams. Automated recall reminders also help ensure patients on therapeutic phlebotomy schedules attend their follow-up appointments, keeping the billing record continuous and complete.

Conclusion

ICD-10 Code D45 is straightforward to assign when the physician’s documentation is complete, but the D45 vs D75.1 distinction and the Type 1 Excludes note create real-world denial risk for practices that don’t have documentation standards in place. Clean D45 coding requires a confirmed diagnosis, documented clinical criteria, and clear separation of any co-occurring conditions.

Pabau’s claims management software gives hematology and specialist practices the tools to validate ICD-10 code pairing before submission, reducing pended claims and protecting reimbursement timelines. To see how Pabau supports accurate coding workflows across chronic disease specialties, book a demo with the team.

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