E21.0 — Primary hyperparathyroidism
Is E21.0 billable?
Yes — E21.0 is billable for FY2027. E21.0 is a valid, billable ICD-10-CM code at the highest level of specificity in its branch. E21.0 may be submitted for encounters from October 1, 2026 through September 30, 2027.
E21.0 at a glance
| Code | E21.0 |
|---|---|
| Description | Primary hyperparathyroidism |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does E21.0 group to?
E21.0 sits in MDC 10 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 643Endocrine Disorders with MCCmedical
- 644Endocrine Disorders with CCmedical
- 645Endocrine Disorders without CC/MCCmedical
How is E21.0 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to E21.0. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Disease, diseased › osteofibrocystic
- Enlargement, enlarged › parathyroid
- Hyperparathyroidism › primary
- Hyperplasia, hyperplastic › parathyroid
- Hypertrophy, hypertrophic › parathyroid
- Osteitis › parathyroid
- Recklinghausen disease › bones
- Osteitis › fibrosa NEC › cystica
- Osteitis › fibrosa NEC › osteoplastica
- Von Recklinghausen › disease › bones
- Curvature › spine › due to or associated with › osteitis › fibrosa cystica
Inclusion terms
Alternative wording in documentation that is classified to E21.0.
- Hyperplasia of parathyroid
- Osteitis fibrosa cystica generalisata [von Recklinghausen's disease of bone]
Excludes1 — never code together — inherited from Chapter 4
The conditions below can never be reported together with E21.0 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- transitory endocrine and metabolic disorders specific to newborn (P70-P74)
Excludes1 — never code together — inherited from E20-E35
The conditions below can never be reported together with E21.0 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Excludes1 — never code together — inherited from E21
The conditions below can never be reported together with E21.0 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Excludes2 — not included here — inherited from E21
The conditions below are not part of E21.0, but a patient may have both at the same time. When documentation supports it, E21.0 and the excluded code may both be reported.
- familial hypocalciuric hypercalcemia (E83.52)
How long has E21.0 existed?
E21.0 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.
Which codes are confused with E21.0?
ICD-10-CM declares these codes mutually exclusive with E21.0 — exactly one of each pair can be correct for a given encounter.