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E21.0 vs E83.52

E21.0 (Primary hyperparathyroidism) compared with E83.52 (Hypercalcemia), from the official CMS tabular data.

Summary

These codes should not be reported together because E83.52’s tabular entry lists E21.0 under Excludes1.

Official rule
What is different?

The conditions named.E21.0 is “Primary hyperparathyroidism”; E83.52 is “Hypercalcemia”.

Registry fact

Can these codes be reported together?

No.E83.52’s entry carries an Excludes1 note covering E21.0: “hyperparathyroidism (E21.0-E21.3)”. Both may be reported only when the documentation shows the two conditions are unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes1 relationship?

Yes.E83.52’s tabular entry: “hyperparathyroidism (E21.0-E21.3)”. The note covers E21.0.

Official ruleGuide: Excludes1 vs Excludes2

Is there an Excludes2 relationship?

Yes.E21.0’s tabular entry: “familial hypocalciuric hypercalcemia (E83.52)”. The note covers E83.52.

Official ruleGuide: Excludes1 vs Excludes2

Is one more specific?

Not comparable.The codes sit in different categories; specificity is only comparable within one category.

Is one a parent or header code?

No.Both are billable codes, and neither contains the other.

Registry fact

Are there sequencing instructions?

None.Neither entry carries a Code First or Use Additional Code note that names the other.

Official rule

Are there other coding relationships?

None found.No laterality, encounter-phase, Table of Neoplasms, Table of Drugs and Chemicals, or history-versus-active-disease relationship links these codes.

MedCoder-derived

Official rule: a tabular instructional note or a section of the ICD-10-CM Official Guidelines, quoted as published. Registry fact: the codes’ own published attributes (titles, billable status, position in the hierarchy, code set). MedCoder-derived: a reading MedCoder computes from those facts; it is not itself a rule. How to read the labels

Can these codes be reported together?

Excludes1 — generally not reported together

Excludes1 conflict

E83.52
Hypercalcemia
↔
E21.0
Primary hyperparathyroidism

What we found

No — do not report together.E83.52 carries an Excludes1 note covering E21.0: “hyperparathyroidism (E21.0-E21.3)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

What to review

Report one of the two. Both may be reported only when the documentation shows the two conditions are unrelated to each other.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes1 note means the two conditions are not ordinarily reported together for the same encounter, because the classification treats them as mutually exclusive forms of the same condition. The documented exception is when the two conditions are unrelated to each other.

Source / rule

CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Informational

Excludes2 relationship

E21.0
Primary hyperparathyroidism
↔
E83.52
Hypercalcemia

What we found

Yes, when both are documented.E21.0 carries an Excludes2 note covering E83.52: “familial hypocalciuric hypercalcemia (E83.52)”

Excludes2 marks distinct conditions — both may be reported when both are documented.

What to review

Report both only when the documentation supports both conditions; otherwise report the one documented.

Guide: Excludes1 vs Excludes2Check these on a claim

Why it matters

An Excludes2 note means the excluded condition is not part of the code above it, but a patient can have both. Report both when both are documented.

Source / rule

CMS ICD-10-CM tabular instructional notes

Official guidance behind these answers

  • Section I.A.12.a — Excludes1 · applies to: Excludes1

    A type 1 Excludes note is a pure excludes note. It means “NOT CODED HERE!” An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition. An exception to the Excludes1 definition is the circumstance when the two conditions are unrelated to each other. If it is not clear whether the two conditions involving an Excludes1 note are related or not, query the provider. For example, code F45.8, Other somatoform disorders, has an Excludes1 note for "sleep related teeth grinding (G47.63)," because "teeth grinding" is an inclusion term under F45.8. Only one of these two codes should be assigned for teeth grinding. However psychogenic dysmenorrhea is also an inclusion term under F45.8, and a patient could have both this condition and sleep related teeth grinding. In this case, the two conditions are clearly unrelated to each other, and so it would be appropriate to report F45.8 and G47.63 together.

    ICD-10-CM Official Guidelines FY2026

  • Section I.A.12.b — Excludes2 · applies to: Excludes2

    A type 2 Excludes note represents “Not included here.” An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

    ICD-10-CM Official Guidelines FY2026

Quoted from the ICD-10-CM Official Guidelines for Coding and Reporting in effect for the release shown. The tabular notes above are the code-level instruction; these sections are the convention that says how such a note is applied. Source document (CMS PDF) · Release and checksum

Side by side

E21.0Primary hyperparathyroidismE83.52Hypercalcemia
Billing statusBillableBillable
ClassificationE00-E89 — Endocrine, Nutritional and Metabolic Diseases (E00-E89)E00-E89 — Endocrine, Nutritional and Metabolic Diseases (E00-E89)
DefinitionPrimary hyperparathyroidism is a billable ICD-10-CM diagnosis code (E21.0).Hypercalcemia is a billable ICD-10-CM diagnosis code (E83.52).
Includes
Hyperplasia of parathyroid
Osteitis fibrosa cystica generalisata [von Recklinghausen's disease of bone]
Familial hypocalciuric hypercalcemia
Excludes1
adult osteomalacia (M83.-)
ectopic hyperparathyroidism (E34.2)
hungry bone syndrome (E83.81)
infantile and juvenile osteomalacia (E55.0)
galactorrhea (N64.3)
gynecomastia (N62)
autoimmune hypoparathyroidism (E20.812)
autosomal dominant hypocalcemia (E20.810)
chondrocalcinosis (M11.1-M11.2)
hungry bone syndrome (E83.81)
hyperparathyroidism (E21.0-E21.3)
secondary hypoparathyroidism in diseases classified elsewhere (E20.811)
dietary mineral deficiency (E58-E61)
parathyroid disorders (E20-E21)
vitamin D deficiency (E55.-)
androgen insensitivity syndrome (E34.5-)
congenital adrenal hyperplasia (E25.0)
hemolytic anemias attributable to enzyme disorders (D55.-)
Marfan syndrome (Q87.4-)
5-alpha-reductase deficiency (E29.1)
Excludes2
familial hypocalciuric hypercalcemia (E83.52)
Ehlers-Danlos syndromes (Q79.6-)

Notes are the code’s own tabular entry, quoted as published. A note that names the other code is the one the verdict above rests on.

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Derived from the official CMS ICD-10-CM tabular data (FY2027). A coding-rule comparison, not billing advice: payer-specific edits and medical-necessity policy are outside its scope. All data sources