ICD-10-CM 2027
ICD-10 code for primary hyperparathyroidism
From the official ICD-10-CM alphabetic index entry “Hyperparathyroidism › primary”. Page updated September 29, 2026.
About coding primary hyperparathyroidism
The ICD-10-CM code for primary hyperparathyroidism is E21.0 (Primary hyperparathyroidism).
Within E21 (hyperparathyroidism and other disorders of parathyroid gland), E21.0 is specifically for primary hyperparathyroidism. Related codes cover secondary hyperparathyroidism, not elsewhere classified (E21.1), other hyperparathyroidism (E21.2), hyperparathyroidism, unspecified (E21.3), 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.
Common questions about primary hyperparathyroidism ICD-10 codes
What is the ICD-10 code for primary hyperparathyroidism?
- E21.0 — Primary hyperparathyroidism.
Is E21.0 billable?
- Yes. E21.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can E21.0 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict E21.0 as a principal diagnosis.
Is E21.0 a CC or MCC?
- No. E21.0 is neither a CC nor an MCC under MS-DRG v44.0.