Primary hyperparathyroidism or hypercalcaemia of malignancy?

The introduction of two-site immunometric assays measuring intact parathyroid hormone (PTH) and radioimmunoassays measuring PTH-related peptide (PTH-RP) have simplified the evaluation of patients with hypercalcaemia. We present a 63-year-old man with recurrent hypercalcaemia after surgical treatment for primary hyperparathyroidism 3 years previously. PTH measured with a mid-region radioimmunoassay gave normal values, at the same level as during his primary hyperparathyroidism. Intact PTH was, however, clearly suppressed, and he had a highly elevated level of PTH-RP. This suggested that he had humoral hypercalcaemia of malignancy. The patient died after 2 months, and at autopsy an adenocarcinoma of the pancreas with no skeletal metastases was found.