What is ICD-10 code D68.51?

D68.51 is the ICD-10-CM diagnosis code for Activated protein C resistance. A genetic condition where blood cells are resistant to a natural anticoagulant protein, increasing the risk of dangerous blood clots. D68.51 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D68.51 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. D68.51 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. D68.51 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.

What is the V28 vs V24 difference for D68.51?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. D68.51 was a payment HCC under V24 (Coagulation Defects and Other Specified Hematological Disorders) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting D68.51?

This is a genetic thrombophilia; document family history of clotting disorders when available Often discovered during evaluation for unexplained thrombosis; link to the thrombotic event code if applicable Because D68.51 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

D68.51: Activated protein C resistance — ICD-10

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupD68.51Effective 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) / Coagulation defects, purpura and other hemorrhagic conditions (D65-D69)

D68.51

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

Activated protein C resistance

A genetic condition where blood cells are resistant to a natural anticoagulant protein, increasing the risk of dangerous blood clots.

Buddy Insight

Activated protein C resistance, most commonly caused by factor V Leiden mutation, is the most prevalent inherited thrombophilia affecting approximately 5% of Caucasian populations.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Mapped

HCC 48

Coagulation Defects and Other...

RAF 0.209

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 48

Coagulation Defects and Other...

RAF 0.0

RXHCC

Not risk-adjusted for this model/period.

RAF 0

Code Trumping

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Code Book Path

Official

D68Other coagulation defects

D68.5Primary thrombophilia

D68.51Activated protein C resistance

Inclusion Terms

Official

Factor V Leiden mutation

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for D68.51 in this effective period.

Related Child Codes

Official

D68.52Prothrombin gene mutation

D68.59Other primary thrombophilia

Includes

Official

ICD-10-CM does not list Includes notes for D68.51 in this effective period.

Excludes 1

Official

antiphospholipid syndrome (D68.61)
lupus anticoagulant (D68.62)
secondary activated protein C resistance (D68.69)
secondary antiphospholipid antibody syndrome (D68.69)
secondary lupus anticoagulant with hypercoagulable state (D68.69)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for D68.51 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for D68.51 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for D68.51 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Document the APC resistance ratio on functional testing and whether the underlying cause is factor V Leiden mutation (confirmed by genetic testing).

Record zygosity (heterozygous or homozygous), personal and family history of venous thromboembolism, and current anticoagulation status.

Note any precipitating factors for thrombotic events.

MEAT Support

HCC Buddy guidance

Document the APC resistance ratio on functional testing and whether the underlying cause is factor V Leiden mutation (confirmed by genetic testing).

Record zygosity (heterozygous or homozygous), personal and family history of venous thromboembolism, and current anticoagulation status.

Note any precipitating factors for thrombotic events.

Audit Caution

HCC Buddy guidance

APC resistance testing may be affected by anticoagulant therapy — document whether testing was performed off anticoagulation.

Factor V Leiden genetic testing provides definitive diagnosis regardless of anticoagulation status.

Not all APC resistance is due to factor V Leiden — rare causes include other factor V mutations and lupus anticoagulant.

Common Mistakes

HCC Buddy guidance

D68.52 (Prothrombin gene mutation) — different genetic thrombophilia with different mechanism

D68.59 (Other primary thrombophilia) — for thrombophilias not specifically classified elsewhere

D68.61 (Antiphospholipid syndrome) — acquired thrombophilia rather than inherited.

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is D68.51 an HCC code?

Yes. D68.51 maps to Coagulation Defects and Other Specified Hematological Disorders under the V24 model but is not retained in V28.

HCC Category Mapping

V24HCC 48, Coagulation Defects and Other Specified Hematological Disorders

0.209

ESRDHCC 48, Coagulation Defects and Other Specified Hematological Disorders

0.000

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 D68.51

For D68.51to 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 D68.51 during that encounter, not just copy-forwarded from a problem list.

What This Code Means

D68.51 is the ICD-10-CM diagnosis code for activated protein c resistance. A genetic condition where blood cells are resistant to a natural anticoagulant protein, increasing the risk of dangerous blood clots. D68.51 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 coagulation defects, purpura and other hemorrhagic conditions (d65-d69).

Under the older CMS-HCC V24 model, D68.51 maps to Coagulation Defects and Other Specified Hematological Disorders (HCC 48) with a community, non-dual, aged base RAF weight of 0.209. 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.

This is a genetic thrombophilia; document family history of clotting disorders when available. Because D68.51 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 D68.51 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a genetic thrombophilia; document family history of clotting disorders when available
•Often discovered during evaluation for unexplained thrombosis; link to the thrombotic event code if applicable

Clinical Significance

Activated protein C resistance, most commonly caused by factor V Leiden mutation, is the most prevalent inherited thrombophilia affecting approximately 5% of Caucasian populations. It increases the risk of venous thromboembolism 3-8 fold in heterozygotes and up to 80-fold in homozygotes. Despite being a prothrombotic condition, it maps to coagulation defect HCCs.

Documentation Requirements

✓Document the APC resistance ratio on functional testing and whether the underlying cause is factor V Leiden mutation (confirmed by genetic testing).
✓Record zygosity (heterozygous or homozygous), personal and family history of venous thromboembolism, and current anticoagulation status.
✓Note any precipitating factors for thrombotic events.

Commonly Confused Codes

•D68.52 (Prothrombin gene mutation): different genetic thrombophilia with different mechanism
•D68.59 (Other primary thrombophilia): for thrombophilias not specifically classified elsewhere
•D68.61 (Antiphospholipid syndrome): acquired thrombophilia rather than inherited.