Calcium Homeostasis

Calcium plays a very significant role in our bodies. Approximately 99 percent of the calcium in our bodies is stored in the teeth and bones. Calcium generates about two percent of our total body weight. Calcium is crucial in bone formation, keeping strong bones and teeth and is known for helping to prevent osteoporosis. Although calcium is mostly thought about in the bones and teeth, it also plays important roles throughout the body. The amount of calcium outside the bones and teeth may be small in comparison to what is inside the bones and teeth, but is very useful in many functions in the body. Calcium is required in functions such as the contraction and relaxation of muscles. This helps in keeping a regular heartbeat. Calcium is also used in clotting of the blood and the transfer of nerve impulses. Calcium is also an influential player in exocytosis and it helps in the regulation of enzyme activity. Calcium can affect the use of other nutrients in the body and how they are absorbed. It can also aid in disease prevention and lowering blood pressure in cases where individuals have high blood pressure. (Kamps, 2012; UMMC, 2011).

There are three hormones that are responsible for maintaining calcium homeostasis in the body. They are the parathyroid hormone, vitamin D and calcitonin. Parathyroid is the main hormone involved in regulating calcium levels. There are four parathyroid glands which lie posterior to the thyroid glands. The cells in the parathyroid gland act in response to the calcium levels in the blood. When the calcium levels are low the cells increase the release of the parathyroid hormone. The parathyroid hormone raises blood calcium levels by triggering the kidneys to raise calcium reabsorption and upregulating enzymes in the kidney that change vitamin D to its activated form. This increases calcium intake in the intestine and resorption from the bone. When vitamin D is changed to the active hormone calcitriol is transported to the blood stream, mainly to the cells in the small intestine. Calcitriol moves to the nucleus of these cells and boost the role of proteins that carry calcium from inside the small intestine to the blood. Calcitonin does the opposite of the parathyroid hormone and vitamin D. While the parathyroid gland and vitamin D raise the calcium levels, calcitonin decreases it. Calcitonin is a hormone secreted by the C cell of the thyroid gland that lowers blood calcium levels by inhibiting bone resorption. (Lingohr-Smith, 2011).

Having high and low levels of calcium in the body affects the body differently. Hypercalcemia is the medical term for high blood calcium. Having too much calcium in the body can lead to an increased risk of kidney stones, constipation, nausea, and high blood pressure. People with hypercalcemia may also have stomach, muscle and joint pain. Very severe hypercalcemia can cause symptoms of brain dysfunction such as confusion, emotional disturbances, delirium, hallucinations, and coma. Irregularly low calcium levels in the blood are known as hypocalcaemia. Your bones and teeth will begin to deteriorate because your body takes the calcium that is stored in your bones to carry out the functions that are dependent on calcium.

Hypocalcaemia can cause fragile bones, brittle nails and can cause frequent muscle cramps. It can also cause joint pain, and put you at risk for bone disease as you age. Low calcium levels can put you at higher risks for high blood pressure or hypertension as well as poor blood clotting. (McDowell, 2008;Kamps,2012). Some people are more likely to experience abnormal levels of calcium. Postmenopausal women may have problems with getting enough calcium due to greater bone loss and not absorbing calcium as well. People who are lactose intolerant may also have a problem getting enough calcium due to the fact that they cannot eat some calcium-rich foods. Vegans and vegetarians may also have a higher chance at having a calcium deficiency since they avoid dairy products, which are a major source of calcium.(Office of Dietary Supplements, 2012).

In a recent study at the University of Alberta, medical researchers studied how diets high in salt could deplete calcium in the body. Researchers believe the link between calcium and sodium is that they are regulated by the same molecule in the body. They found that when the body gets rid of sodium through urine, it also gets rid of calcium. This is important because our intake of sodium is constantly increasing in our diets. This means our bodies are constantly disposing of calcium along with the sodium.

This is another reason that a low sodium diet is important. It has been known for a while that this molecule was in charge of absorption of sodium in the body, but finding out that it is also responsible in regulating calcium levels is new. These researchers discovered that calcium and sodium absorption are linked. In their research, they worked with specimens that didn’t have this molecule. The specimens’ urine had high levels of calcium. Since the calcium wasn’t absorbed and kept in the body, the bones became thin. This shows that the molecule that was not present in the specimens is needed for calcium absorption. In a journal written about this research it was mentioned that this molecule may become a drug target to treat kidney stones and osteoporosis.( University of Alberta Faculty of Medicine & Dentistry,2012).

References

Kamps, Arielle.(2012). Role of Calcium in the Body’s Nutrition. San Francisco Chronicle. Retrieved from http://healthyeating.sfgate.com/role-calcium-bodys-nutrition-1265.html

Lingohr-Smith, Melissa.(2011). Hormone Which Regulates Blood Calcium Levels. Retrieved from http://www.livestrong.com/article/168604-hormones-which-regulate-blood-calcium-levels/

McDowell, Patrick.(2008). The Importance of Calcium. Healthy Living Nutrition. Retrieved from http://healthylifejournal.org/healthy-living/the-importance-of-calcium/

Office of Dietary Supplements.(2012). Calcium. National Institutes of Health. Retrieved from http://ods.od.nih.gov/factsheets/Calcium-QuickFacts/

University of Alberta Faculty of Medicine & Dentistry.(2012).Diets High in Salt Could Deplete Calcium in the Body. Retrieved from http://www.sciencedaily.com/releases/2012/07/120724131604.htm

University of Maryland Medical Center(UMMC) (2011).Calcium. Retrieved from http://www.umm.edu/altmed/articles/calcium-000290.htm

Zabell, Martin.(2009). Effects of High Calcium. Retrieved from http://www.livestrong.com/article/41502-effects-high-calcium/