E83.31
BillableFamilial hypophosphatemia
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is E83.31 an HCC code?
Yes. E83.31 maps to Glycogen/Amino-Acid/Other Metabolic Disorders under the CMS-HCC V28 risk adjustment model.
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 E83.31
For E83.31 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 E83.31 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
E83.31 is the ICD-10-CM diagnosis code for familial hypophosphatemia. Familial hypophosphatemia is an inherited condition where the body cannot properly regulate phosphate levels, resulting in abnormally low phosphate in the blood. This genetic disorder affects how the kidneys handle phosphate and can lead to weak bones and other complications. E83.31 sits in the ICD-10-CM chapter for endocrine, nutritional and metabolic diseases (e00-e89), within the section covering metabolic disorders (e70-e88).
Under the CMS-HCC V28 risk adjustment model, E83.31 maps to Glycogen/Amino-Acid/Other Metabolic Disorders (HCC 50) with a community, non-dual, aged base RAF weight of 0.289. E83.31 was not retained as a payment HCC under the older V24 model, so V28 introduced or recategorized it during the 2024–2026 phase-in. 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 code is specific to familial (inherited) hypophosphatemia; do not use it for hypophosphatemia due to other causes such as malnutrition, medications, or refeeding syndrome. Because E83.31 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 E83.31 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is specific to familial (inherited) hypophosphatemia; do not use it for hypophosphatemia due to other causes such as malnutrition, medications, or refeeding syndrome
- •Document the family history and genetic nature of the condition in the medical record to support the use of this specific code rather than the more general hypophosphatemia codes
Clinical Significance
Familial hypophosphatemia (including X-linked hypophosphatemia) is a rare hereditary disorder of renal phosphate wasting that causes rickets in children and osteomalacia in adults. It requires lifelong management with phosphate supplements and active vitamin D, and its chronic nature makes it significant for risk adjustment.
Documentation Requirements
- ✓Confirmed familial/hereditary etiology of hypophosphatemia
- ✓Genetic testing results if available (PHEX, FGF23-related mutations)
- ✓Serum phosphorus levels and renal phosphate wasting documentation
- ✓Current treatment regimen (phosphate supplements, calcitriol, burosumab)
- ✓Assessment of skeletal complications (rickets, osteomalacia, fractures, dental abnormalities)
- ✓Family history supporting hereditary nature
Excludes 1 — Do NOT code together
- vitamin D-deficiency rickets (E55.0)