Bone metabolism is significantly influenced by the activity of osteoblasts and osteoclasts, the calciotropic hormones 1,25-dihydroxy vitamin D hormone, parathyroid hormone and calcitonin, and the extracellular calcium concentration.
Calcitonin is a peptide hormone which acts as an antagonist of the parathyroid hormone and is produced in the parathyroid gland. The production and secretion of calcitonin is stimulated by an elevated calcium level and results in a reduction in the calcium concentration in the blood.
Calcitonin serodiagnostics are generally employed for clarification of scintigraphically cold thyroid nodules. The calcitonin level in serum is strongly increased in medullary thyroid carcinoma (C-cell carcinoma). Hyperparathyroidism is present in 20% to 30% of patients with a C-cell carcinoma. Furthermore, calcitonin serodiagnostics are required in paraneoplastic or reactive hypercalcaemia and for monitoring and relapse monitoring following surgical removal of C-cell carcinoma. Unspecifically increased values can be measured in the final trimester of pregnancy, in people taking contraceptives and after calcium infusion. Low calcitonin levels are associated with osteopenia, a preliminary stage of osteoporosis, which is why calcitonin is among the substances given in osteoporosis therapy.