Cells and organs in a human body are known to work in a system manner. People tend to forget the presence of hormones in the human body that plays an important role in regulating the many body systems. While you may have been used to knowing a bit about reproductive hormones such as estrogen and testosterone, other hormones such as calcitonin may seem a new thing if you are not used to reading or learning about hormones in humans. If you are put on a blood test, you may have seen levels of calcitonin and some people with high calcitonin levels might ask a doctor what causes this.
To answer this, you have to know a bit more about the calcitonin hormones first. Calcitonin is a hormone that is produced and released by the parafollicular cells (also known as C-cells) of the thyroid gland. Calcitonin plays a role in regulating the calcium level in blood. It also regulates phosphorus in the blood. Calcitonin works to reduce calcium level by either inhibiting the activity of osteoclasts or decreasing resorption of calcium in kidneys. Osteoclasts are cells that degrade the bone that are involved in remodelling of bones and maintain bone mass. As bone degrades, calcium in the bone is released into the blood system. Hence, inhibition of osteoclast by calcitonin reduces the amount of calcium from being released into the blood.
Calcitonin is stimulated when there is an increase of calcium in blood. It is also stimulated by the gut hormones such as gastrin. Calcitonin is known to maintain the calcium in the body so that it reaches the state of balance (calcium homeostasis). When level of calcium in blood is low, calcitonin secretion decreases and parathyroid hormones kick in to increase blood calcium level. Inhibition of calcitonin not only is caused by the low level of blood calcium but is also inhibited by the hormone somatostatin which is released by the C-cells. Calcitonin is also known to stimulate the production of vitamin D in the kidney.
A calcitonin test is a test that measures the level of calcitonin in blood samples. In normal state, a person will have a small amount of calcitonin in their blood. However, when the calcitonin test reveals high amounts, it may be signs of diseases. Common causes of high calcitonin levels are either C-cell hyperplasia or medullary thyroid cancer. Both of these conditions are quite rare. C-cell hyperplasia is an abnormal growth C-cell in the thyroid glands that can turn into medullary thyroid cancer. However, other causes such as certain medications, other types of cancers and pregnancies may lead to high calcitonin levels.
Calcitonin is measured in picograms per millilitres (pg/mL). The normal value is 8.4 pg/mL or less for male and 5.0 pg/mL or less for females. It is worth noting that the normal values may vary slightly according to the measurement of the laboratory that runs the calcitonin test. Patients with calcitonin levels of more than 100 pg/mL have high risk for medullary thyroid carcinoma. Patients with values 10 to 100 pg/mL have less than 25% risk for medullary thyroid carcinoma.
A person may be recommended to get calcitonin test when they show suspicion of medullary thyroid cancer or C-cell hyperplasia. Symptoms such as lump in the front of the neck, swollen lymph nodes or swollen glands in the neck, pain in the throat, changes in voice commonly hoarse voice, choking sensation, persistent cough without cold and diarrhoea are common in patients with medullary thyroid cancer. Thus, when a person presents with symptoms such as mentioned just now, calcitonin test helps to verify if they really have the cancer.
Beside calcitonin test to detect medullary thyroid cancer, it is also used to check for multiple endocrine neoplasia type 2 (MEN 2). MEN 2, also known as Sipple syndrome is a rare familiar syndrome that affects thyroid, adrenal and parathyroid glands. It is caused by a mutation in a gene known as RET. People with family history of MEN 2 do have high chances for developing medullary thyroid cancer. Regular calcitonin tests can help detect the cancer before any symptoms occur.
It can be concluded that calcitonin hormones do play an important role in calcium homeostasis. While low calcitonin level does not cause any clinical effect on the body, high calcitonin levels should be taken seriously especially when patients do have symptoms related to C-cell hyperplasia and/or medullary thyroid cancer. High calcitonin levels are consequences of the disease and not a direct cause. Calcitonin tests not only help detect the cancer but also help in monitoring treatment and to check if the cancer returned even after treatment. In some cases, a more accurate test known as “calcitonin stimulation test” can help differentiate C-cell hyperplasia or medullary thyroid cancers. The calcitonin test is not the only test to diagnose medullary thyroid cancer. Healthcare professionals will do many other tests such as imaging tests and biopsy procedures to confirm a diagnosis. Many people can live with medullary thyroid cancer for many years especially when it is detected and treated early. The survival rates for patients with this cancer is not very accurate as there are so few patients.