E05.40 ICD-10-CM Code: Thyrotoxicosis factitia without thyrotoxic crisis or storm
HCC Buddy Code Card
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FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Disorders of thyroid gland (E00-E07)
E05.40
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceThyrotoxicosis factitia without thyrotoxic crisis or storm
Overactive thyroid caused by taking too much thyroid hormone medication or supplements, without thyroid storm.
Buddy Insight
Thyrotoxicosis factitia results from intentional or inadvertent excessive exogenous thyroid hormone ingestion, distinguishing it from endogenous causes of hyperthyroidism.
CMS-HCC V28
00
RAF 0
CMS-HCC V24
00
RAF 0
ACA/HHS
00
RAF 0
ESRD/PACE
00
RAF 0
RXHCC
MappedHCC 44
RAF 0.0
Code Trumping
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Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for E05.40 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for E05.40 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for E05.40 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for E05.40 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for E05.40 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for E05.40 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for E05.40 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 E05.40 an HCC code?
No. E05.40 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
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 E05.40
For E05.40to 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 E05.40 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
E05.40 is the ICD-10-CM diagnosis code for thyrotoxicosis factitia without thyrotoxic crisis or storm. Overactive thyroid caused by taking too much thyroid hormone medication or supplements, without thyroid storm. E05.40 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering disorders of thyroid gland (e00-e07).
E05.40 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Maps to RxHCC 44 (Osteoporosis, Vertebral and Pathological Fractures) in the prescription drug model. This code does not map to CMS-HCC v28 or v24 models. The RxHCC mapping supports risk adjustment for prescription drug costs related to thyroid medication management.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for E05.40 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Factitia means self-induced; verify documentation indicates intentional or unintentional overdose of thyroid medication
- •Consider coding an external cause code (Y92 series) if medication overdose is involved
Clinical Significance
Thyrotoxicosis factitia results from intentional or inadvertent excessive exogenous thyroid hormone ingestion, distinguishing it from endogenous causes of hyperthyroidism. Common scenarios include overzealous thyroid replacement therapy, intentional ingestion for weight loss, or accidental overdose. The condition is clinically significant because treatment is dose adjustment or cessation rather than antithyroid drugs or ablation.
Documentation Requirements
- ✓Document the source of exogenous thyroid hormone (prescribed medication, supplement, or surreptitious use), the specific medication and dosage involved, thyroid function tests, and explicitly state that thyrotoxic crisis is absent.
- ✓Record whether the ingestion was intentional or iatrogenic and the clinical response to dose modification.