E21.3
✓ BillableHyperparathyroidism, unspecified
Endocrine, nutritional and metabolic diseases (E00-E89)
❌ Excludes1
inheritedRules inherited from parent codes in the hierarchy.
- • adult osteomalacia (M83.-)
- • ectopic hyperparathyroidism (E34.2)
- • hungry bone syndrome (E83.81)
- • infantile and juvenile osteomalacia (E55.0)
⚠️ Excludes2
inheritedRules inherited from parent codes.
- • familial hypocalciuric hypercalcemia (E83.52)
Clinical Description
ICD-10-CM code E21.3 represents hyperparathyroidism, unspecified. This code falls under the Endocrine, nutritional and metabolic diseases (E00-E89) classification. It is a billable/specific code valid for HIPAA-covered transactions as of October 1, 2025 (FY2026). This code can be used to indicate a diagnosis for reimbursement purposes on insurance claims.
This is a 5-character code at the 4th level of specificity. This is the most specific code available in this subcategory. Coders should note that E21.3 has 4 Excludes1 restriction(s) — codes that cannot be reported together on the same claim.
Frequently Asked Questions
What is ICD-10 code E21.3?
ICD-10-CM code E21.3 is "Hyperparathyroidism, unspecified". It belongs to the category: Endocrine, nutritional and metabolic diseases (E00-E89).
Is E21.3 a billable ICD-10 code?
Yes, E21.3 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
What codes are excluded with E21.3?
E21.3 has 4 Excludes1 rule(s). These codes are mutually exclusive and cannot be coded together on the same claim.
Can E21.3 be coded with other codes?
E21.3 has 1 Excludes2 note(s). These conditions can be coded together if both are documented in the patient record.
Related Codes in E21
Other codes in the same category that may be relevant for differential coding:
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Data Source
CMS ICD-10-CM 2026 Tabular List
Updated October 1, 2025 (FY2026)