What is ICD-10 code D57.42?

D57.42 is the ICD-10-CM diagnosis code for Sickle-cell thalassemia beta zero without crisis. It belongs to the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89). D57.42 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D57.42 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. D57.42 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. D57.42 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does D57.42 map to under V28?

D57.42 maps to CMS-HCC V28 HCC 107 (Sickle Cell Anemia (Hb-SS) and Thalassemia Beta Zero). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM D57.42: Sickle-cell thalassemia

D57.42 maps to CMS-HCC V28 107. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC Buddy coding tools

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Code lookupD57.42

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89) / Hemolytic anemias (D55-D59)

D57.42

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

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.

Buddy Insight

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 107

Sickle Cell Anemia (Hb-SS) an...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 070

HHS-HCC 070 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 46

Severe Hematological Disorders

Code-level coefficient reference

RXHCC

Mapped

HCC 95

Sickle Cell Anemia

Code-level coefficient reference

Code Book Path

Official

D57Sickle-cell disorders D57.4Sickle-cell thalassemia D57.42Sickle-cell thalassemia beta zero without crisis

Inclusion Terms

Official

HbS-beta zero without crisis
Sickle-cell beta zero without crisis
Sickle-cell beta thalassemiaInherited from D57.4
Thalassemia Hb-S diseaseInherited from D57.4

Excludes 2

Official

autoimmune disease (systemic) NOS (M35.9)Inherited from D50-D89
certain conditions originating in the perinatal period (P00-P96)Inherited from D50-D89
complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from D50-D89
congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)Inherited from D50-D89
endocrine, nutritional and metabolic diseases (E00-E88)Inherited from D50-D89
human immunodeficiency virus [HIV] disease (B20)Inherited from D50-D89
injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from D50-D89
neoplasms (C00-D49)Inherited from D50-D89
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from D50-D89

Related Codes

Official

D57.40Sickle-cell thalassemia without crisis D57.41Sickle-cell thalassemia, unspecified, with crisis D57.43Sickle-cell thalassemia beta zero with crisis D57.44Sickle-cell thalassemia beta plus without crisis D57.45Sickle-cell thalassemia beta plus with crisis

Includes

Official

No Includes notes are included in this display for D57.42. Check the code and parent instructions in the Code Book.

Excludes 1

Official

other hemoglobinopathies (D58.-)Inherited from D57

Code First

Official

No Code First sequencing instructions are included in this display for D57.42. Check the code and parent instructions in the Code Book.

Use Additional

Official

code for any associated fever (R50.81)Inherited from D57

Code Also

Official

No Code Also instructions are included in this display for D57.42. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

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.

MEAT Support

HCC Buddy guidance

Confirm no acute crisis at the encounter.

Audit Caution

HCC Buddy guidance

Ensure the provider documents 'beta-zero' or 'beta-0' specifically.

Do not assign crisis codes simultaneously with D57.42.

Common Mistakes

HCC Buddy guidance

D57.42 vs. D57.1 (Hemoglobin SS without crisis) -

clinically similar but genetically distinct; hemoglobin electrophoresis can distinguish them. D57.42 vs. D57.44 (Beta plus without crisis) -

beta-zero has more severe phenotype than beta-plus. D57.42 vs. D57.40 (Unspecified sickle-cell thalassemia without crisis) -

D57.42 provides critical specificity for accurate HCC mapping.

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is D57.42 an HCC code?

Yes. D57.42 (Sickle-cell thalassemia beta zero without crisis) maps to HCC 107, Sickle Cell Anemia (Hb-SS) and Thalassemia Beta Zero under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.457. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: D57.42 is billable and maps to V28 HCC 107, Sickle Cell Anemia (Hb-SS) and Thalassemia Beta Zero. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: D57.42
Description: Sickle-cell thalassemia beta zero without crisis
HCC (V28): HCC 107 — Sickle Cell Anemia (Hb-SS) and Thalassemia Beta Zero
RAF reference coefficient: 0.457
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 107, Sickle Cell Anemia (Hb-SS) and Thalassemia Beta Zero

0.457

ESRDHCC 46, Severe Hematological Disorders

Not separately weighted

RxHCCHCC 95, Sickle Cell Anemia

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work D57.42 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for D57.42

For D57.42, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

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

Coder workflow notes

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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 source-labeled community, non-dual, aged reference coefficient of 0.457. No V24 mapping is shown for D57.42; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

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. For D57.42, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. 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, source-labeled coefficient references, 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.

Commonly Confused Codes

•D57.42 vs. D57.1 (Hemoglobin SS without crisis) -
•clinically similar but genetically distinct; hemoglobin electrophoresis can distinguish them. D57.42 vs. D57.44 (Beta plus without crisis) -
•beta-zero has more severe phenotype than beta-plus. D57.42 vs. D57.40 (Unspecified sickle-cell thalassemia without crisis) -
•D57.42 provides critical specificity for accurate HCC mapping.