E31.23
BillableMultiple endocrine neoplasia [MEN] type IIB
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E31.23 an HCC code?
Yes. E31.23 maps to Other Significant Endocrine and Metabolic Disorders under the CMS-HCC V28 risk adjustment model (and Other Significant Endocrine and Metabolic 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 E31.23
For E31.23to 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 E31.23 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E31.23 is the ICD-10-CM diagnosis code for multiple endocrine neoplasia [men] type iib. A hereditary condition where tumors develop in the thyroid and adrenal glands, along with characteristic physical features like mucosal growths. E31.23 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering disorders of other endocrine glands (e20-e35).
Under the CMS-HCC V28 risk adjustment model, E31.23 maps to Other Significant Endocrine and Metabolic Disorders (HCC 51) with a community, non-dual, aged base RAF weight of 0.233. Under the older V24 model, E31.23 mapped to the same category but with a base RAF weight of 0.230 — V28 recalibrated weights across the entire model. 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.
Document associated features such as medullary thyroid carcinoma, pheochromocytoma, and mucosal neuromas. Because E31.23 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 E31.23 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document associated features such as medullary thyroid carcinoma, pheochromocytoma, and mucosal neuromas
- •Ensure distinction from MEN type I; MEN IIB includes medullary thyroid cancer and pheochromocytoma as key features
Clinical Significance
Multiple endocrine neoplasia type IIB (formerly type III) is the most aggressive multiple endocrine neoplasia variant, also caused by RET proto-oncogene mutations but with distinct clinical features including early-onset medullary thyroid carcinoma, pheochromocytoma, mucosal neuromas, marfanoid habitus, and intestinal ganglioneuromatosis. Medullary thyroid carcinoma typically develops in infancy or early childhood.
Documentation Requirements
- ✓Document RET mutation analysis (commonly M918T mutation), medullary thyroid carcinoma status and calcitonin levels, pheochromocytoma screening results, characteristic physical features (mucosal neuromas of lips and tongue, marfanoid body habitus), gastrointestinal symptoms from ganglioneuromatosis, and prophylactic thyroidectomy timing.
Commonly Confused Codes
- •E31.22 (multiple endocrine neoplasia type IIA which lacks mucosal neuromas and marfanoid habitus), E31.21 (multiple endocrine neoplasia type I with different organ involvement), E31.20 (unspecified multiple endocrine neoplasia), Q87.40 (Marfan syndrome which has similar body habitus but different etiology).