E83.31 ICD-10-CM Code: Familial hypophosphatemia
E83.31 maps to CMS-HCC V28 50. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software
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FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Metabolic disorders (E70-E88)
E83.31
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceFamilial 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.
Buddy Insight
Familial hypophosphatemia (including X-linked hypophosphatemia) is a rare hereditary disorder of renal phosphate wasting that causes rickets in children and osteomalacia in adults.
CMS-HCC V28
MappedHCC 50
Coefficient HCC 50: 0.648 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
N/A—
Not mapped
ESRD/PACE
N/A—
Not mapped
RXHCC
MappedHCC 42
Code-level coefficient reference
Code Book Path
Inclusion Terms
Official- Vitamin D-resistant osteomalacia
- Vitamin D-resistant rickets
Excludes 2
Official- Ehlers-Danlos syndromes (Q79.6-)Inherited from E70-E88, E83.3
- disorders of pyrophosphate metabolism (E83.82-)Inherited from E70-E88, E83.3
Related Codes
Includes
OfficialNo Includes notes are included in this display for E83.31. Check the code and parent instructions in the Code Book.
Excludes 1
Official- vitamin D-deficiency rickets (E55.0)
- transitory endocrine and metabolic disorders specific to newborn (P70-P74)Inherited from E00-E89, E70-E88, E83, E83.3
- androgen insensitivity syndrome (E34.5-)Inherited from E00-E89, E70-E88, E83, E83.3
- congenital adrenal hyperplasia (E25.0)Inherited from E00-E89, E70-E88, E83, E83.3
- hemolytic anemias attributable to enzyme disorders (D55.-)Inherited from E00-E89, E70-E88, E83, E83.3
- Marfan syndrome (Q87.4-)Inherited from E00-E89, E70-E88, E83, E83.3
- 5-alpha-reductase deficiency (E29.1)Inherited from E00-E89, E70-E88, E83, E83.3
- dietary mineral deficiency (E58-E61)Inherited from E00-E89, E70-E88, E83, E83.3
- parathyroid disorders (E20-E21)Inherited from E00-E89, E70-E88, E83, E83.3
- vitamin D deficiency (E55.-)Inherited from E00-E89, E70-E88, E83, E83.3
- adult osteomalacia (M83.-)Inherited from E00-E89, E70-E88, E83, E83.3
- osteoporosis (M80.-)Inherited from E00-E89, E70-E88, E83, E83.3
Code First
OfficialNo Code First sequencing instructions are included in this display for E83.31. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for E83.31. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for E83.31. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 E83.31 an HCC code?
Yes. E83.31 (Familial hypophosphatemia) maps to HCC 50, Amyloidosis, Porphyria, and Other Specified Metabolic Disorders under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.648. 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: E83.31 is billable and maps to V28 HCC 50, Amyloidosis, Porphyria, and Other Specified Metabolic Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- E83.31
- Description
- Familial hypophosphatemia
- HCC (V28)
- HCC 50 — Amyloidosis, Porphyria, and Other Specified Metabolic Disorders
- RAF reference coefficient
- 0.648
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
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 E83.31 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for E83.31
For E83.31, 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
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 Amyloidosis, Porphyria, and Other Specified Metabolic Disorders (HCC 50) with a source-labeled community, non-dual, aged reference coefficient of 0.648. No V24 mapping is shown for E83.31; 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.
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. For E83.31, 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 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)
Commonly Confused Codes
- •E83.30: Disorder of phosphorus metabolism, unspecified: lacks the specificity and HCC mapping of familial hypophosphatemia
- •E83.39: Other disorders of phosphorus metabolism: use for acquired or non-familial phosphorus disorders
- •E55.0: Rickets, active: nutritional rickets from vitamin D deficiency, not genetic phosphate wasting
- •N25.0: Renal osteodystrophy: secondary phosphorus disorder from chronic kidney disease