ICD-10-CM 2027
ICD-10 code for hyperparathyroidism
From the official ICD-10-CM alphabetic index entry “Hyperparathyroidism”. Page updated September 29, 2026.
About coding hyperparathyroidism
The ICD-10-CM code for hyperparathyroidism is E21.3 (Hyperparathyroidism, unspecified). The official index lists 5 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on E21.3.
Within E21, choose E21.3 (Hyperparathyroidism, unspecified) only when documentation doesn't support a more specific option: primary hyperparathyroidism (E21.0), secondary hyperparathyroidism, not elsewhere classified (E21.1), other hyperparathyroidism (E21.2), other specified disorders of parathyroid gland (E21.4) and disorder of parathyroid gland, unspecified (E21.5).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 643 (Endocrine Disorders with MCC, relative weight 1.6139), DRG 644 (Endocrine Disorders with CC, relative weight 1.0044) and DRG 645 (Endocrine Disorders without CC/MCC, relative weight 0.7459), in MDC 10 (Endocrine, Nutritional and Metabolic Diseases and Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific hyperparathyroidism codes (official index)
Common questions about hyperparathyroidism ICD-10 codes
What is the ICD-10 code for hyperparathyroidism?
- E21.3 — Hyperparathyroidism, unspecified. More specific codes apply when the documentation supports them: E21.0, N25.81, E21.1, E21.2 and others below.
What is the ICD-10 code for primary hyperparathyroidism?
- E21.0 — Primary hyperparathyroidism.
What is the ICD-10 code for secondary hyperparathyroidism?
- N25.81 — Secondary hyperparathyroidism of renal origin.
What is the ICD-10 code for tertiary hyperparathyroidism?
- E21.2 — Other hyperparathyroidism.
Is E21.3 billable?
- Yes. E21.3 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can E21.3 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict E21.3 as a principal diagnosis.
Is E21.3 a CC or MCC?
- No. E21.3 is neither a CC nor an MCC under MS-DRG v44.0.