ICD-10 Code E21.0 – Primary hyperparathyroidism (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E21.0 – Primary hyperparathyroidism
What it is
Primary hyperparathyroidism is a disorder in which the parathyroid glands make too much hormone on their own. You use E21.0 when documentation identifies the primary form, not a secondary cause.
Clinical signs
Clinical features vary; refer to documentation. Common findings include elevated parathyroid hormone with hypercalcemia, and patients may have kidney stones, bone loss, fatigue, or nonspecific abdominal complaints.
When to use this code
Use this code when the provider documents primary hyperparathyroidism or a parathyroid adenoma causing autonomous hormone excess. It also fits confirmed cases being evaluated for hypercalcemia when the diagnosis is stated clearly in the record.
Do not use for
Do not use E21.0 for secondary or tertiary hyperparathyroidism, which have separate codes. If the record only says hypercalcemia or parathyroid disorder without confirming the primary form, check documentation.
Coding tip
Code E21.0 only when the chart supports a primary parathyroid disorder; otherwise, query for clarification.