Calcium (Ca)
Why this test?
- First of all, it is worth noting that the results of this test indicate the amount of calcium not in the bones, but in the blood.
- For the diagnosis and control of certain pathological conditions related to the bone, heart, nervous system, as well as the kidneys and teeth.
- As part of a biochemical analysis during a routine examination.
- If the obtained indicators are outside the normal range, it is necessary to do additional tests - for ionized calcium, calcium in urine, phosphorus, magnesium, vitamin D, parathyroid hormone. Often, the balance between these substances is much more important than just their concentrations individually. These indicators help to determine the cause of disturbed calcium levels in the body: lack of its supply or excess excretion by the kidneys.
- In the control of nephrolithiasis, bone diseases and neurological disorders.
- For a preliminary assessment of calcium metabolism.
In what cases is it prescribed?
During a scheduled preventive medical examination. In case of kidney diseases (since the level of calcium decreases in people with kidney failure). In diseases associated with calcium metabolism disorders, such as pathology of the thyroid gland, small intestine, cancer. With certain changes in the electrocardiogram (shortened ST segment at a low calcium level, prolongation of the ST segment and QT interval). When the patient has symptoms of increased calcium level - hypercalcemia: loss of appetite, nausea, vomiting, constipation, abdominal pain, frequent urination, strong thirst, bone pain, rapid fatigue, weakness, headache, apathy, depression of consciousness up to coma. With symptoms of low calcium level - hypocalcemia: spastic abdominal pain, tremor of the fingers, numbness around the mouth, carpopedal spasm, arrhythmia, facial muscle spasms, numbness, tingling, muscle cramps. With some malignant neoplasms (especially with cancer of the lung, breast, brain, throat, kidney and multiple myeloma). In case of kidney disease or after transplantation of one of them. If necessary, monitoring the effectiveness of calcium metabolism therapy with calcium and/or vitamin D drugs.
Test information
Calcium is one of the most important minerals for humans. It is necessary for the contraction of skeletal muscles and the heart, for the transmission of nerve impulses, as well as for normal blood coagulation (contributes to the transition of prothrombin to thrombin), for building the framework of bones and teeth.
About 99% of this mineral is concentrated in the bones and only less than 1% circulates in the blood. Almost half of the calcium in the blood is metabolically active (ionized), the rest is associated with proteins (mainly albumins) and anions (lactate, phosphate, bicarbonate, citrate) and is inactive.
Total calcium in the blood is the concentration of its free (ionized) and bound forms. Only free calcium can be used by the body.
A part of calcium is excreted in the urine every day. To maintain the balance between the release and use of this mineral, it should be about 1 g per day.
When the concentration of calcium in the blood increases, the level of phosphate decreases, when the content of phosphate increases, the proportion of calcium decreases.
Mechanisms of phosphorus-calcium exchange: parathyroid glands with a high phosphate content (at a low calcium level) secrete parathormone, which destroys bone tissue, thereby increasing the concentration of calcium, with a high level of calcium in the blood, the thyroid gland produces calcitonin, which causes the movement of calcium from the blood into bones, parathyroid hormone activates vitamin D, increasing absorption of calcium in the gastrointestinal tract and reabsorption of the cation in the kidneys.
