Unchanged parathyroid function following irradiation for malignancies of the head and neck

Irradiation to the neck increases the prevalence of hyperparathyroidism and may cause parathyroid insufficiency. In this study, 35 patients who received therapeutic irradiation to the neck and a control group comprising 19 patients who received radiation to the bladder were studied before, during, and until 2 months after irradiation in order to see whether there were any measurable changes in the parathyroid function. In both groups the serum concentrations of calcium, phosphate and parathyroid hormone were unchanged. Serum protein and albumin decreased in the bladder cancer group. The results support the concept that the parathyroid gland has a low radiation sensitivity, and radiation induced changes may not manifest itself before years after irradiation, due to the low mitotic activity.