Background Primary hyperparathyroidism (PHPT) is a disease process traditionally thought to present during middle age, but can occur at any age. The purpose of this study was to compare PHPT patient characteristics based on patient age at the time of surgical referral. Methods A retrospective review of a prospectively managed database of adult patients undergoing parathyroid surgery for PHPT was conducted. Patients with a negative family history, no previous parathyroid surgery, and ≥6-mo follow-up were included. Patients were grouped by age for comparison. Results From 2001-2012, 1372 patients met inclusion criteria. Age groups were as follows: ≤50 y, 51-60 y, 61-70 y, and >70 y. Female predominance increased with age (P > 0.01). Baseline serum parathyroid hormone levels were higher at the extremes of age (P < 0.001). Young patients had the highest serum calcium (P < 0.01), urinary calcium (P < 0.001), and T-score (P < 0.001) measures, and greater incidence of vitamin D deficiency (P = 0.03). The use of local anesthesia increased with age, whereas use of outpatient parathyroidectomy decreased with age (both P < 0.01). Rates of disease persistence (2.3%-2.9%, P = 0.95) and recurrence (2.1%-3.3%, P = 0.75) were low, and did not differ. Conclusions Patients at the extremes of age are referred with more elevated laboratory indices whereas those in the traditional age range have milder biochemical indices. This may result from differential surgical referral. Individuals with laboratory evidence of abnormal calcium and parathyroid hormone regulation should be evaluated for parathyroidectomy regardless of age because all ages can be successfully treated. © 2014 Elsevier Inc. All rights reserved.