Health care providers diagnose primary hyperparathyroidism when a person has high blood calcium and PTH levels. High blood calcium is usually the first sign that leads health care providers to suspect parathyroid gland overactivity. Other diseases can cause high blood calcium levels, but only in primary hyperparathyroidism is the elevated calcium the result of too much PTH.

Routine blood tests that screen for a wide range of conditions, including high blood calcium levels, are helping health care providers diagnose primary hyperparathyroidism in people who have mild forms of the disorder and are symptom-free. For a blood test, blood is drawn at a health care provider’s office or commercial facility and sent to a lab for analysis.