Trait overview: Blood calcium level
Monday, May 04, 2020. Author FitnessGenes
Monday, May 04, 2020. Author FitnessGenes
While we often think of calcium as being particularly important for healthy bones and teeth, this mineral is also essential for heart function, muscle contraction and nerve signalling.
Calcium is both a micronutrient and macromineral:
Many of calcium’s functions in the body stem from the fact that it forms an ion: an electrically charged atom.
The movement of calcium ions into and out of cells causes differences in electrical charge and voltage across cell membranes.
This principle is central to heart contraction, skeletal and smooth muscle contraction, and nerve signalling.
There are three main areas where our body stores calcium:
In order for cells to use calcium for internal biochemical and signalling processes, they must be kept topped up with calcium ions supplied by the blood.
Nerve and muscle function
As calcium ions carry an electrical charge, maintaining a constant level of calcium both inside and outside of cells stabilises the voltage across cell membranes. This is important for healthy nerve, muscle and heart function.
On a related note, calcium ions regulate the opening and closing of special channels called voltage-gated ion channels. These allow other ions such as sodium, potassium and chloride to enter nerve and muscle cells, which affects their electrical excitability. This has an effect on transmission of nerve signals and muscle contraction.
If calcium levels in the blood are too low, these voltage-gated channels are more likely to be open, making nerves and muscle cells more overly excitable. In some cases, this can lead to muscle spasms.
Conversely, if calcium levels in the blood are too high, voltage-gated channels are more likely to remain closed, making nerves and muscle less excitable.
If you’ve ever cut yourself shaving, you’ll notice that the bleeding soon stops. This is due to the formation of blood clots, which are made from a molecule called fibrin.
Calcium is essential for the formation of fibrin and various other stages in blood clotting. Low levels of calcium in the blood can therefore delay blood clotting.
Calcium levels in the blood are kept within a strict range by constantly adjusting the rate at which calcium is absorbed, excreted, and converted into bone mineral.
The three main organs that regulate blood calcium levels are:
Levels of blood calcium are monitored by a special calcium-sensing receptor (CaSR), located in the parathyroid gland, thyroid and kidneys.
When calcium levels fall, less calcium binds to the CaSR, triggering the increased production of a hormone called parathyroid hormone (PTH).
PTH then increases calcium levels in the blood by stimulating:
When calcium levels rise, more of it binds to the CaSR receptor. This suppresses the release of PTH and instead, causes your thyroid gland to releases a hormone called calcitonin.
Calcitonin helps to reduce blood calcium levels by:
The FitnessGenes blood calcium level trait combines a number of genetic factors that influence calcium metabolism to predict whether members are at risk of high blood calcium levels. It also accounts for your age.
Depending on the genetic variants that they carry, FitnessGenes members are placed into one of six individual trait bands:
1) low, 2) medium and 3) high risk of high blood calcium (young)
4) low, 5) medium and 6) high risk of high blood calcium (old)
One of the genes that we analyse includes the CASR gene, which encodes the CaSR protein. Variants of this gene affect how well your parathyroid glands and kidneys respond to changes in serum calcium levels. They therefore partly influence your risk of low or high blood calcium levels.
For those at risk of high blood calcium levels, limiting dietary intake of calcium to 1200mg per day as well as monitoring Vitamin D levels is important. Supplementing with magnesium at night can also help with general muscle relaxation and reduce PTH secretion.
Are you at an increased risk of high blood calcium levels? Discover your personal blood calcium trait alongside 75+ other fitness related traits by unlocking your unique genetic code with FitnessGenes.
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