D57.42
BillableSickle-cell thalassemia beta zero without crisis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D57.42 an HCC code?
Yes. D57.42 maps to Sickle Cell Anemia (Hb-SS) and Thalassemia Beta Zero under the CMS-HCC V28 risk adjustment model (and Severe Hematological Disorders under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for D57.42
For D57.42 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed D57.42 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D57.42 is the ICD-10-CM diagnosis code for sickle-cell thalassemia beta zero without crisis. This is a genetic blood disorder where a person has both sickle cell disease and a severe form of thalassemia (a condition affecting hemoglobin production), but they are not currently experiencing a painful crisis or acute complication. The person's red blood cells are abnormally shaped and their body cannot produce normal hemoglobin. D57.42 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering hemolytic anemias (d55-d59).
Under the CMS-HCC V28 risk adjustment model, D57.42 maps to Sickle Cell Anemia (Hb-SS) and Thalassemia Beta Zero (HCC 107) with a community, non-dual, aged base RAF weight of 0.727. Under the older CMS-HCC V24 model, D57.42 maps to Severe Hematological Disorders (HCC 46) with a community, non-dual, aged base RAF weight of 0.666. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code only when the patient has confirmed sickle-cell thalassemia beta zero and is NOT in crisis; if crisis is present, use D57.41 instead. Because D57.42 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D57.42 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the patient has confirmed sickle-cell thalassemia beta zero and is NOT in crisis; if crisis is present, use D57.41 instead
- •This is a combination diagnosis code that captures both conditions simultaneously, so do not code sickle cell disease and thalassemia separately
Clinical Significance
Sickle-cell thalassemia beta zero without crisis represents the chronic baseline state of patients who co-inherit a sickle hemoglobin gene and a beta-zero thalassemia gene (producing no beta-globin from the thalassemia allele). This genotype produces a clinical phenotype virtually identical to Hemoglobin SS disease because all beta-globin produced is the sickle variant. These patients have severe chronic hemolytic anemia, frequent vaso-occlusive crises, and the same organ damage risk as Hemoglobin SS patients.
Documentation Requirements
- ✓Documentation must confirm sickle-cell thalassemia beta zero genotype through hemoglobin electrophoresis (showing predominantly Hemoglobin S with elevated Hemoglobin F and absent Hemoglobin A) or molecular genetic testing.
- ✓Confirm no acute crisis at the encounter.
- ✓Record baseline hemoglobin, reticulocyte count, medications (hydroxyurea dosing), transfusion schedule, and comprehensive organ surveillance results including echocardiogram, renal function, ophthalmologic exam, and transcranial Doppler results.