Calcium: what is its norm in the blood?
Calcium is a trace element, which, in terms of its content in the body, significantly exceeds the quantitative composition of other chemical elements. Calcium (Ca 2+) solves many problems, providing important functions of the human body.
Blood calcium contains no more than 1% of the total amount of calcium in the body. The remaining 99% is accounted for by the teeth and skeleton, in which calcium is represented by the mineral Ca 10 (PO 4) 6 (OH) 2 and is combined with phosphorus.
- Normal blood calcium levels range from 2.0-2.8 mmol / L. According to some reports, the normal range can be 2.15-2.5 mmol / l.
- 1.1-1.4 mmol / L is the normal level of ionized calcium in the blood.
- 0.1-0.4 g of calcium is excreted from the body by the kidneys of a healthy person along with urine every 24 hours.
- Why do we need calcium?
- What determines the level of calcium in the blood?
- Causes of low blood calcium levels
- Symptoms of low and high blood calcium levels
- What can affect the results of the analysis?
- When are additional research methods required?
Why do we need calcium?
Determination of the level of calcium in the blood is often required for the diagnosis of various diseases.
Indeed, in the body, he is responsible for many important functions:
- Without calcium, normal muscle contractility is impossible.
- Calcium takes part in the transmission of nerve impulses, regulates the rhythms of the heart. These functions are controlled by calcium along with magnesium.
- Calcium stimulates the work of many enzymes, participates in the metabolic processes of iron.
- Teeth and bones would not have their strength if there were not enough calcium and phosphorus in them.
- Calcium affects cell permeability.
- Calcium takes part in the formation of a thrombotic clot at the stage of conversion of prothrombin to thrombin. If the trace element is not enough, then normal blood clotting is impossible.
- Calcium activates the work of some of the hormones in the body.
- Calcium is involved in the normal functioning of the endocrine glands. So, without it, the parathyroid gland cannot fully work.
- Calcium is involved in the processes of cellular reception, in which cells exchange information with each other.
- A person cannot be healthy if there is not enough calcium in his body. Without this trace element, high-quality and full sleep is impossible.
Normal values of calcium in the body depend on the person's age:
- 1.90-2.60 - newborn baby in the first 10 days of life.
- 2.25-2.75 - a child over 10 days old and under the age of 2 years.
- 2.20-2.70 - child 2-4 years old.
- 2.10-2.55 - a teenager 12-18 years old.
- 2.15-2.50 - adult 18-60 years old.
- 2.20 -2.55 - elderly person 60-90 years old.
- 2.05-2.40 - people over 90 years old.
Depending on the age and gender of a person, the daily intake of calcium will differ.
The dosage is presented in milligrams:
- 200 - for children under 6 months.
- 400 - for children from six months to a year.
- 600 - for children 1-4 years old.
- 1000 - for children 4-11 years old.
- 1200 - for teenagers 11-17 years old.
- 1200 - for all adults.
- 1200 - for men 50-70 years old.
- 1400 - for women 50-70 years old.
- 1300 - for people over 70.
- 1500 - for women expecting a child or breastfeeding mothers.
It should not be assumed that high amounts of calcium in the body are beneficial to health. If its concentration in plasma exceeds the permissible values, then this leads to a drop in the level of phosphorus. If there is little calcium in the blood, then the amount of phosphates in it will begin to increase. Both of these conditions are pathological and entail disturbances in the most important functions of the body.
What determines the level of calcium in the blood?
The level of calcium in the blood has a direct relationship with its metabolism in the bones of the skeleton, with the quality of its absorption in the intestine and reabsorption by the kidneys. Other trace elements are responsible for the balance of calcium in the body, primarily magnesium and phosphorus. Also capable of increasing or lowering the level of calcium in the blood are sex hormones, hormones of the endocrine glands, adrenal glands, as well as the active form of vitamin D3.
So, the following components influence the level of calcium in the blood more strongly than others:
- Parathyroid hormone (parathyroid hormone). It is produced by the parathyroid glands. With its excessive release, as well as against the background of an increased content of phosphorus in the blood, the processes of inhibition of the formation of bone tissue will be launched in the body. Parathyroid hormone leads to the fact that the level of calcium in the blood rises, and in the bones it becomes less.
- Calcitonin, on the other hand, lowers the level of calcium in the blood, transporting it to the bone tissue.
- Vitamin D3, which is produced in the active form by the kidneys, can lead to an increase in the level of calcium in the blood, as it enhances the absorption of this trace element in the intestine.
In the blood, calcium can be present in several forms:
Calcium ions - CA 2+. This form of calcium is called free or ionized. Of the total amount of calcium, the ionized trace element accounts for about 55-58%.
- Calcium, which is associated with protein fractions. It accounts for about 35-38%.
Calcium salts which account for about 10%. Calcium present in the blood in this form is called complexed. It can act in conjunction with phosphates - Ca 3 (PO 4) 2, citrates - Ca 3 (C 6 H 5 O 7) 2, lactates - 2 (C 3 H 5 O 3) * Ca) and bicarbonates - Ca (HCO 3).
If doctors talk about an increase in the level of calcium in the blood, then they mean that all its forms are increased. Only ionized calcium exhibits metabolic activity. It is he who is more involved in all the needs of the human body. Moreover, for the diagnosis of various conditions, it is not required to determine the amount of ionized calcium. This study is highly specialized. To obtain adequate data, you can establish the total level of this trace element in the blood.
If the concentration of protein in the blood is low, then the analysis may show normal calcium levels. To find its real values, you will need to apply a technique that is aimed at calculating the ionized form of the trace element, since it is this that replaces the complexed form of calcium. More research is needed to identify such a deficiency.
If a person with chronic diseases has a low level of protein in the blood, then this leads to the development of a calcium deficiency in serum. Most often, a similar situation is observed with lesions of the kidneys and liver. The level of this microelement also decreases, provided that a person does not receive it with food. In women carrying a child, there may be a drop in calcium levels, but the concentration of albumin in the blood will always be reduced.
Causes of low blood calcium levels
Hypocalcemia is the scientific name for a condition that characterizes low blood calcium levels. Most often, its fall is caused by a decrease in the level of albumin (a protein component of blood). In this case, a deficiency of only protein-bound calcium occurs, and ionized calcium remains within the normal range.
Other reasons that can lead to hypocalcemia:
- Malfunction of the parathyroid glands, the ingestion of parathyroid hormone into the bloodstream.
- The absence of parathyroid glands as a result of the operation.
- Lack of vitamin D.
- Renal failure of a chronic course, nephritis.
- Spasmophilia and rickets in a child.
- Acute magnesium deficiency in the human body.
- The body's immunity to the effects of parathyroid hormone, due to congenital malformations.
- Low calcium content in food that a person consumes.
- High level of phosphate in the blood.
- Severe diarrhea.
- Serious liver damage (cirrhosis).
- The presence in the body of osteoblastic metastases, which require a lot of calcium to continue their pathological growth.
- Hyperplastic changes in adrenal tissue.
- Taking medicines for the treatment of epilepsy.
- Transfusion of impressive volumes of blood, which contains citrate.
- Alkalosis in the acute phase.
- Diseases such as: alcoholism, acute pancreatitis, colitis. They are combined into one group, since each of them does not allow calcium to be normally absorbed into the blood from the gastrointestinal tract.
Symptoms of low and high blood calcium levels
The level of calcium in the blood is determined not only in the presence of any pathologies, but also when an absolutely healthy person undergoes a medical examination. However, this study cannot reflect the exact condition of the bone tissue.
The following symptoms will indicate a high level of calcium in the blood:
- Complete or partial lack of appetite.
- Attacks of nausea, which may be accompanied by vomiting.
- Constipation tendency.
- Abdominal pain.
- Frequent night trips to the toilet to empty the bladder.
- Constant thirst.
- Bone pain.
- Increased fatigue.
- Blues, depression and apathy.
Low blood calcium levels will be indicated by symptoms such as:
- Abdominal cramps.
- Tremor of hands and fingers.
- Numbness in the region of the nasolabial triangle.
- Spasms of the muscles of the feet and hands.
If a person does not have signs indicating a deficiency or an excess of calcium, but the analysis indicates the opposite, then a comprehensive examination is necessary.
For this, diagnostic measures such as:
- Determination of the level of ionized calcium in the blood.
- Determination of the level of calcium in the blood.
- Determination of the level of phosphorus in the blood.
- Determination of the level of magnesium in the blood.
- Determination of the level of vitamin D in the blood.
Determination of the level of parathyroid hormone.
Sometimes, in order to diagnose a particular disease, it is required to find out the ratio of calcium in the blood in relation to other substances. For example, such studies can determine the excessive excretion of calcium in the urine, or its insufficient intake along with food.
If the patient suffers from kidney failure, or he underwent a transplant of this organ, then the level of calcium in the blood is measured in a planned manner. Also, this analysis is performed in all patients with myeloma and ECG abnormalities, with tumors of a malignant nature in the chest, lungs, thyroid gland, brain and throat.
What can affect the results of the analysis?
In a newborn child, starting from the 4th day of his birth, an increase in the level of calcium in the blood occurs, which is a physiological norm. This process can be observed both in the body of children born on time and in premature babies.
In adults, calcium levels can increase with the following drugs:
- Antacid medicines.
- Hormonal drugs: androgens, progesterone, parathyroid hormone.
Vitamins A, D 3, D 2.
- Medicines containing lithium salts.
The following drugs can reduce the level of calcium in the blood:
- Preparations for the elimination of seizures.
- Magnesium salts.
- Laxative medicines.
Other reasons that may affect the analysis results:
- Sampling of hemolyzed serum for analysis.
- Blood sampling against the background of dehydration.
- Blood sampling against the background of hypervolemia, which can be observed with the intravenous administration of impressive volumes of isotonic solution.
Useful Information About Blood Calcium:
- In premature infants with low body weight, blood is taken daily for determination of ionized calcium. This avoids the development of hypocalcemia, which in the early stages may not manifest itself in any way.
- Calcium levels in urine and blood do not reflect bone calcium levels. To determine the level of calcium in the bones, a diagnostic method such as densitometry is used.
- The older a person is, the lower their blood calcium level. The same applies to pregnant women.
- The higher the level of albumin in the blood, the higher the level of calcium. This protein has no effect on ionized calcium.
Before taking the analysis, you will need to stop eating for 12 hours. 30 minutes before the procedure, you need to exclude any physical activity, do not smoke and be in a calm state.
When are additional research methods required?
It is imperative to determine the degree of activity of calcium ions, provided that its level in the blood is reduced or increased, and symptoms of these disorders develop. The ionized calcium level is measured at pH = 7.40.
You can also measure the calcium content in urine, which will determine the amount of a trace element excreted by the kidneys. This study is carried out with changes in the concentration of calcium in the blood.
The author of the article: Shutov Maxim Evgenievich | Hematologist
Education: In 2013 he graduated from the Kursk State Medical University and received a diploma "General Medicine". After 2 years, completed residency in the specialty "Oncology". In 2016 completed postgraduate studies at the National Medical and Surgical Center named after N. I. Pirogov.