E20.0 ICD-10-CM Code: Idiopathic hypoparathyroidism
E20.0 is not a CMS-HCC payment code. MEAT criteria · RAF Calculator · HCC Buddy coding tools
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FY 2026 Apr update / Endocrine, nutritional and metabolic diseases (E00-E89) / Disorders of other endocrine glands (E20-E35)
E20.0
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceIdiopathic hypoparathyroidism
A condition where the parathyroid glands do not produce enough parathyroid hormone due to an unknown cause, leading to low calcium levels in the blood.
Buddy Insight
E20.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 030
Code-level coefficient reference
ESRD/PACE
MappedHCC 23
Code-level coefficient reference
RXHCC
MappedHCC 43
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for E20.0. Check the code and parent instructions in the Code Book.
Excludes 2
OfficialNo Excludes 2 notes are included in this display for E20.0. Check the code and parent instructions in the Code Book.
Related Codes
Includes
OfficialNo Includes notes are included in this display for E20.0. Check the code and parent instructions in the Code Book.
Excludes 1
Official- transitory endocrine and metabolic disorders specific to newborn (P70-P74)Inherited from E00-E89, E20-E35, E20
- galactorrhea (N64.3)Inherited from E00-E89, E20-E35, E20
- gynecomastia (N62)Inherited from E00-E89, E20-E35, E20
- Di George's syndrome (D82.1)Inherited from E00-E89, E20-E35, E20
- postprocedural hypoparathyroidism (E89.2)Inherited from E00-E89, E20-E35, E20
- tetany NOS (R29.0)Inherited from E00-E89, E20-E35, E20
- transitory neonatal hypoparathyroidism (P71.4)Inherited from E00-E89, E20-E35, E20
Code First
OfficialNo Code First sequencing instructions are included in this display for E20.0. Check the code and parent instructions in the Code Book.
Use Additional
OfficialNo Use Additional Code instructions are included in this display for E20.0. Check the code and parent instructions in the Code Book.
Code Also
OfficialNo Code Also instructions are included in this display for E20.0. 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 E20.0 an HCC code?
E20.0 is not in the CMS-HCC V28 or V24 community payment model. E20.0 has a separate mapping under the CMS-HCC ESRD model (HCC 23 (Other Significant Endocrine and Metabolic Disorders)) and the Part D RxHCC model (HCC 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders)); the applicable result needs member context. E20.0 also appears in the HHS-HCC commercial risk model (HCC 030 (HHS-HCC 030 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping.
- Code
- E20.0
- Description
- Idiopathic hypoparathyroidism
- HCC (V28)
- No CMS-HCC V28 mapping
- RAF reference coefficient
- —
- 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 E20.0 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for E20.0
For E20.0, 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
E20.0 is the ICD-10-CM diagnosis code for idiopathic hypoparathyroidism. A condition where the parathyroid glands do not produce enough parathyroid hormone due to an unknown cause, leading to low calcium levels in the blood. E20.0 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).
E20.0 has no mapping under the CMS-HCC V28 or V24 community payment models. E20.0 has a separate mapping under the CMS-HCC ESRD model (HCC 23 (Other Significant Endocrine and Metabolic Disorders)) and the Part D RxHCC model (HCC 43 (Pituitary, Adrenal Gland, and Other Endocrine and Metabolic Disorders)); the applicable result needs member context. E20.0 also appears in the HHS-HCC commercial risk model (HCC 030 (HHS-HCC 030 adult, RAF varies by metal level)), which is a commercial market model rather than a Medicare Advantage payment mapping. Do not assign V28 risk adjustment value from this page; verify the applicable model and payment year before using this code for risk adjustment.
Verify that the hypoparathyroidism is truly idiopathic (no identifiable cause) before assigning this code.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for E20.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Verify that the hypoparathyroidism is truly idiopathic (no identifiable cause) before assigning this code
- •Do not use this code if the condition is secondary to another disease or autoimmune process
Clinical Significance
E20.0 identifies idiopathic hypoparathyroidism, a rare endocrine disorder characterized by insufficient parathyroid hormone production without an identifiable cause. This results in chronic hypocalcemia and hyperphosphatemia, manifesting as neuromuscular irritability, tetany, seizures, cardiac arrhythmias, and long-term complications including basal ganglia calcification and cataracts.
Documentation Requirements
- ✓Documentation must include the diagnosis of hypoparathyroidism, laboratory evidence of low parathyroid hormone levels with hypocalcemia and hyperphosphatemia, and confirmation that the cause is idiopathic (no surgical, autoimmune, or genetic etiology identified).
- ✓Calcium and vitamin D replacement therapy should be documented.
Commonly Confused Codes
- •E20.811 (secondary hypoparathyroidism) for post-surgical or radiation-induced disease
- •E20.812 (autoimmune hypoparathyroidism) when autoimmune etiology is established
- •E20.9 (hypoparathyroidism unspecified) when the type is not documented
- •E89.2 (postprocedural hypoparathyroidism) after thyroid/parathyroid surgery.