ICD10
ICD-10 Code E21: Hyperparathyroidism and other disorders of parathyroid gland
Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026
What is this code?
ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Endocrine, nutritional and metabolic diseases (E00-E89).
đź“‹Clinical overview
This ICD-10 code is commonly used when documentation describes hyperparathyroidism or another parathyroid-gland disorder in the E21 family. The most accurate code depends on whether the record identifies primary, secondary, other, unspecified, or another specified parathyroid disorder.
When is it used?
- May be used when a clinician documents hyperparathyroidism and other disorders of parathyroid gland in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
- This entry may represent a broader category rather than the most specific billable code.
đź©şClinical context
When commonly used
- Endocrinology, nephrology, primary-care, inpatient, and utilization-review workflows where hypercalcemia, parathyroid-hormone excess, or another parathyroid disorder is part of the active assessment.
- Coding workflows where the chart identifies primary versus secondary hyperparathyroidism or clarifies another specified parathyroid-gland disorder that changes final code specificity.
Common management context
- Evaluation often includes calcium, phosphorus, vitamin D, renal-function, and parathyroid-hormone review, symptom assessment for nephrolithiasis or bone effects, and endocrine follow-up planning.
- Documentation usually becomes more specific when the chart identifies primary versus secondary hyperparathyroidism, or clarifies another specified versus unspecified parathyroid-gland disorder.
- Specialist context already linked on this page includes Endocrinologist, General Physician.
🔍Key distinctions
Important notes
- This ICD-10 family captures hyperparathyroidism and closely related parathyroid-gland disorders rather than hypoparathyroidism, thyroid disease, or unrelated endocrine causes of calcium imbalance.
- Mechanism detail, such as primary, secondary, other, unspecified, or another specified parathyroid-gland disorder, drives final code specificity inside this family.
- This parent page groups hyperparathyroidism and other parathyroid-gland disorder patterns, so the final billable code usually depends on whether the chart identifies primary, secondary, other, unspecified, or another specified parathyroid disorder more specifically.
- Documentation that describes hyperparathyroidism or another parathyroid-gland disorder is coded differently from hypoparathyroidism, thyroid disease, or other endocrine causes of calcium imbalance.
Important exclusions
- adult osteomalacia (M83.-)
- ectopic hyperparathyroidism (E34.2)
- hungry bone syndrome (E83.81)
- infantile and juvenile osteomalacia (E55.0)
- familial hypocalciuric hypercalcemia (E83.52)
Related codes to consider
E21.0Primary hyperparathyroidism
Related hyperparathyroidism ICD-10 code; documentation often becomes more specific when the chart identifies primary versus secondary disease, or clarifies another specified versus unspecified parathyroid-gland disorder.
E21.1Secondary hyperparathyroidism, not elsewhere classified
Related hyperparathyroidism ICD-10 code; documentation often becomes more specific when the chart identifies primary versus secondary disease, or clarifies another specified versus unspecified parathyroid-gland disorder.
E21.2Other hyperparathyroidism
Related hyperparathyroidism ICD-10 code; documentation often becomes more specific when the chart identifies primary versus secondary disease, or clarifies another specified versus unspecified parathyroid-gland disorder.
E21.3Hyperparathyroidism, unspecified
Related hyperparathyroidism ICD-10 code; documentation often becomes more specific when the chart identifies primary versus secondary disease, or clarifies another specified versus unspecified parathyroid-gland disorder.
Code hierarchy
chapter
4Endocrine, nutritional and metabolic diseases (E00-E89)
block
E20-E35Disorders of other endocrine glands
currentE20-E35
Official coding notes
Excludes1 (do not code together)
- adult osteomalacia (M83.-)
- ectopic hyperparathyroidism (E34.2)
- hungry bone syndrome (E83.81)
- infantile and juvenile osteomalacia (E55.0)
Excludes2 (may code together if documented)
- familial hypocalciuric hypercalcemia (E83.52)
Where you may see this code
You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.
Related specialists
EndocrinologistGeneral Physician
Related codes
Sibling codes
E20HypoparathyroidismE22Hyperfunction of pituitary glandE23Hypofunction and other disorders of the pituitary glandE24Cushing's syndromeE25Adrenogenital disordersE26HyperaldosteronismE27Other disorders of adrenal glandE28Ovarian dysfunctionE29Testicular dysfunctionE30Disorders of puberty, not elsewhere classifiedE31Polyglandular dysfunctionE32Diseases of thymusE34Other endocrine disordersE35Disorders of endocrine glands in diseases classified elsewherebillable
Coding guidelines
Compatibility
Legacy code aligns to an official FY 2026 category. Frontend should resolve to the official category page and surface the billable child codes.
Legacy codes
E21
Replacement codes
E21.0 — Primary hyperparathyroidismE21.1 — Secondary hyperparathyroidism, not elsewhere classifiedE21.2 — Other hyperparathyroidismE21.3 — Hyperparathyroidism, unspecifiedE21.4 — Other specified disorders of parathyroid glandE21.5 — Disorder of parathyroid gland, unspecified
Common synonyms
Hyperparathyroidism and other disorders of parathyroid gland
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.