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Calcitonin

Calcitonin, a peptide hormone secreted by the parafollicular cells of the thyroid gland, inhibit osteoclast activity and promotes renal calcium excretion:when is ministered can lower serum calcium levels rapidly within 12 to 24 hours, but the reductions are small.

Has a molecular weight of 3500 and contains 32 amino acid residues.

From parafollicular cells, known as clear or C cells in the thyroid gland.

Secretion is increased when the thyroid is perfused by blood with a high Ca++ concentration.

Secreted when plasma calcium levels reaches approximately 9.5 mg/dL.

Decreases blood calcium levels via the calcitonin receptor in the intestines, bones, kidneys, and brain.

Beta-adrenergic agonists, dopamine, estrogens, gastrin, CCK. glucagon, and secretin increase secretion.Gastrin is the most potent stimulus to secretion.

Levels elevated in Zollinger-Ellison syndrome and in pernicious anemia, processes associated with elevated gastrin levels.

Half-life of less than 10 minutes.

Potent phospaturic agent and will lead to hypophosphatemia without phosphate replacement therapy.

A biomarker for detection of medullary thyroid cancer, and serum levels below 10 pg/mL are considered to be evidence of the absence of medullary thyroid cancer, whereas levels above 100 pg/mL are highly predictive of medullary thyroid cancer.

Synthetic salmon calcitonin, a hormone that suppresses osteoclast activity and reduces bone loss.

Calcitonin inhibits bone resorption and may increase BMD in the spine by up to 3%. 

 

Calcitonin is generally reserved for persons who cannot tolerate other medications for osteoporosis.

 

Calcitonin has also been found to reduce bone pain from vertebral compression fractures.

The use of calcitonin blocks bone resorption and also increases urinary calcium excretion by inhibiting renal calcium reabsorption.

Calcitonin can be given intramuscularly or subcutaneously, and is usually used in life-threatening hypercalcaemia with other modalities of treatment.

Calcitonin helps prevent recurrence of hypercalcemia.

Calcitonin dose is 4 Units per kg via subcutaneous or intramuscular route every 12 hours.

In addition to occurring in medullary thyroid cancer (MTC), elevated calcitonin results may also be seen in patients with any of the following:

Hypercalcemia

Hypergastrinemia

Neuroendocrine tumors

Renal insufficiency

Papillary and follicular thyroid carcinomas

Goiter

Chronic autoimmune thyroiditis

Prolonged treatment with omeprazole (greater than 2 to 4 months), beta-blockers, and glucocorticoids

Also, the presence of heterophilic antibodies to calcitonin can falsely elevate serum calcitonin levels.

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