LAUSR

BACKGROUND There is limited long term follow up of patients undergoing parathyroidectomy. Recurrence is described as 4-10%. This study evaluated persistence and recurrence of hypercalcemia in primary hyperparathyroidism (PHPT) after parathyroidectomy. METHODS Single-institution retrospective (1965-2010) population-based cohort from Olmsted County (MN) of patients undergoing surgery for PHPT. Patients' demographic data, pre- and post-operative laboratory values, clinical characteristics, surgical treatment and follow-up were noted. RESULTS 345 patients were identified, 75.7% female, and median age 58.4 y (IQR 17.6). 68% of patients were asymptomatic and the most common symptoms were musculoskeletal complaints (28.4%) and nephrolithiasis (25.6%). Pre-operative median serum calcium was 11 mg/dL (IQR 10.8-11.4 mg/dL), and median PTH was 90 pg/mL (IQR 61-169 pg/dL). Bilateral cervical exploration was performed in 38% and single gland resection in 79% of cases. Median post-operative serum calcium was 9.2 mg/dL (IQR 5.5-11.3). 9% of patients presented persistence of hypercalcemia, and recurrence was found in 14% of patients. Highest post-operative median serum calcium was 10 mg/dL (IQR 6-12.4), and median number of post-operative calcium measurements was 10 (IQR 0-102). Post-operative hypercalcemia was identified in 37% of patient. 53% were attributed to secondary causes, most commonly medications, 22%. 3% of patients required treatment for post-operative hypercalcemia. Median time to recurrence and death were 12.2 and 16.7 years respectively. CONCLUSION Recurrent hypercalcemia after successful parathyroidectomy is higher than previously reported. Most cases are transient and often associated to other factors with only the minority requiring treatment. Long term follow-up of serum calcium should be considered in patients after successful parathyroidectomy.