ICD-10 Code D72.821 – Monocytosis (symptomatic) (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D72.821 – Monocytosis (symptomatic)
What it is
Monocytosis means an increased number of monocytes in the blood. This code describes the finding when it is documented as symptomatic or clinically relevant.
Clinical signs
Clinical features vary; refer to documentation. Monocytosis may appear with signs of infection, inflammation, autoimmune disease, or other underlying disorders, but the code itself reflects the laboratory finding.
When to use this code
Use D72.821 when the provider documents monocytosis as a diagnosis or significant abnormal finding. It is appropriate when the elevated monocyte count is being evaluated, followed, or noted as part of the encounter record.
Choose this code when monocytosis is the stated reason for assessment, even if the underlying cause is not yet confirmed. Check documentation if the record only mentions a blood count abnormality without a clear diagnosis.
Do not use for
Do not use this code for nonspecific abnormal blood tests unless monocytosis is specifically documented. Do not substitute it for a confirmed underlying condition when that condition is the focus of care.
Coding tip
Code the documented finding, and also capture any confirmed cause when the record supports it.