ICD-10 Code E21.3 – Hyperparathyroidism, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E21.3 – Hyperparathyroidism, unspecified
What it is
This code identifies hyperparathyroidism when the record does not specify whether it is primary, secondary, or tertiary. Use it for documented parathyroid hormone excess without a more precise subtype.
Clinical signs
Clinical features vary; refer to documentation. Commonly noted findings may include elevated parathyroid hormone, calcium abnormalities, kidney stones, bone disease, or nonspecific symptoms such as fatigue.
When to use this code
Use E21.3 when the provider documents hyperparathyroidism but does not identify the cause or type. It is also appropriate when the chart confirms parathyroid overactivity and no further detail is available. If the subtype is later clarified, code the more specific diagnosis instead.
Do not use for
Do not use this code for hypoparathyroidism or for hypercalcemia alone without documented hyperparathyroidism. Check documentation if the record names a specific form such as primary or secondary hyperparathyroidism.
Coding tip
Query for the exact type whenever the note says only “hyperparathyroidism” and the clinical context is unclear.