[In the labyrinth of calcium metabolism].

The authors present the case of a 27-year-old male patient. In 2010, he suffered from a bone fracture of the pelvis. As imaging techniques showed multiple osseal lytic lesions, diagnostic investigations were performed for multiple myeloma. Later, a mass lesion measuring 37 mm in size was removed from the left side of his mandible. Histology revealed a giant-cell tumour of the bone and oncologic therapy was considered. However, before this planned treatment a PET-CT was performed, which showed numerous distinct lesions with enhanced glucose metabolism in the skeleton as well as in soft tissue behind the right lobe of the thyroid. Hence, the patient was referred to endocrinologists. On the basis of severe hypercalcemia (serum calcium 3.66 mmol/l) and high serum parathyroid hormone level (162.5 pmol/l) the diagnosis of a right sided parathyroid tumour was established. After surgical excision of the parathyroid tumour, high levels of serum calcium and parathyroid hormone returned to normal. Histology failed to show malignancy and the patient recovered soon. This case report may shed some light on the importance of serum calcium measurements and the differential diagnostic significance of primary hyperparathyroidism.