Long-term effects of parathyroid operation on serum calcium and parathyroid hormone values in sporadic primary hyperparathyroidism.

BACKGROUND. This study investigates 410 persons (median age, 67 years) who underwent parathyroid operation for sporadic primary hyperparathyroidism 6 to 32 years (mean, 14.2 years) before 1991. METHODS. Patient records and operative specimens were scrutinized, the patients answered a questionnaire, and fasting serum samples were analyzed for calcium, albumin, creatinine, and intact parathyroid hormone (PTH) values. RESULTS. After primary parathyroid operations were performed with a conservative surgical approach, persistent and recurrent hypercalcemia were noticed in 3.7% and 1.7% of patients, respectively, whereas 4.7% of patients required vitamin D substitution or had essentially mild hypocalcemia. The PTH values were generally increased in patients with postoperative hyperparathyroidism, low in those with vitamin D substitution, and normal to elevated in the patients with hypocalcemia and in those with postoperative normocalcemia. The mean serum creatinine concentration was just below the upper reference range and correlated strongly with serum PTH value. No significant differences in serum PTH values were present between the normocalcemic patients and matched control patients after operation (n = 107), but the patients who underwent operation exhibited greater variation in the PTH concentration. CONCLUSIONS. The results substantiate the efficacy of parathyroid operation in sporadic primary hyperparathyroidism. Biochemical derangements compatible with secondary hyperparathyroidism may evolve during long-term follow-up and contribute to decreases in serum calcium values and increases in serum PTH values of these patients.