Too little calcium in the blood (hypocalcaemia), vitamin D deficiency and lazy parathyroids (hypoparathyroidism)

What is it about ?

Calcium is an essential element for, among other things, bone building. The calcium content in the blood is regulated by an interaction between

• Parathyroid hormone (hormone produced by the parathyroid glands),;
• Calcitonin (hormone produced by the thyroid gland);
• Phosphate;
• Vitamin D.

The balance between these substances ensures the balance of calcium metabolism.

When the level of calcium is too low in the blood, it is called hypocalcemia or calcium deficiency. The possible causes of calcium deficiency are:

• Insufficient functioning of the parathyroids: this laziness most often occurs after an operation of the thyroid or parathyroids, it is then transient;
• Vitamin D deficiency due to malnutrition, lack of sunlight, liver disease and prolonged use of certain epilepsy medications;
• Kidney failure;
• Rarer causes: taking bisphosphonates (medicines against osteoporosis) in case of vitamin D deficiency, serious infection or illness requiring intensive care.

How to recognize it?

A slight calcium deficiency rarely causes complaints. With severe deficiency, you may experience muscle spasms (tetany) and laryngeal cramps (which cause transient difficulty in breathing) and severe heart rhythm disturbances may occur. You may also have other symptoms, such as tingling or numbness, most often around your mouth or in your fingers and toes.

A lack of vitamin D can weaken the bones. It can also be manifested by muscle weakness, pain in the bones, broken bones and deformities.

How is the diagnosis made?

If you report the above complaints to your doctor, he may perform a few tests as part of his physical examination:

• he triggers Chvostek’s sign by tapping lightly on the cheek with a reflex hammer. If you develop a muscle cramp in your jaw, the sign is “positive”.
• it triggers Trousseau’s sign by raising the blood pressure in a blood pressure cuff above your systolic blood pressure (“peak blood pressure”). If you develop a severe muscle cramp in your hand, the sign is “positive”.

However, these tests can be normal even with hypocalcemia. This is why the doctor always adds a blood test to measure calcium and vitamin D, and to check kidney function. The amount of calcium is also measured in the urine.

What can you do ?

Calcium
Adequate intake of calcium in the diet is crucial: first during childhood to build quality bone, then to maintain bone mass in adulthood, and finally to minimize mass loss. bone. Adequate calcium intake is necessary throughout life.

In adults, we recommend an intake of 950 mg of calcium per day through the diet. In young people, between 11 and 18 years old, because the bones are developing and growing, 1150 mg per day is recommended.

Important dietary sources of calcium are cheeses, milk, vegetable drinks fortified with calcium, mineral waters, and plant food sources (for example, green vegetables).

For dairy products: 1 glass of milk or calcium fortified drink (200 ml) contains approximately 250 mg of calcium, a small slice of cheese (5 g) contains approximately 50 mg, while a 125 g jar of yogurt , 35 g of cheese spread, 1 serving of cottage cheese (100 g), 1 glass of buttermilk, 1 glass of drinkable yogurt, 1 jar of calcium-enriched soy yogurt contain approximately 180 mg of calcium. It is advisable to avoid products with added sugars.

Bread, sardines, green vegetables (broccoli, Chinese cabbage, watercress, etc.) and legumes also contain calcium. Nuts (walnuts, almonds, hazelnuts, pistachios), dried apricots and dried figs are also sources of calcium, as are certain types of mineral or spring water (more than 150 mg of calcium / liter) or than tap water rich in lime (“hard” water).

Vitamin D
Vitamin D is needed to absorb calcium from food. The main sources of vitamin D are sunlight, fish, egg yolks and dairy products. The recommended daily allowance for adults is 10 to 15 µg. For pregnant women, breastfeeding women, the recommendation is 20 µg of vitamin D per day.

Sunlight is the most important stimulating factor for vitamin D production. Indeed, vitamin D is produced in the skin under the influence of ultraviolet (UV) rays. In most cases, it is sufficient to expose yourself to sunlight for 15 minutes a day with your hands and face uncovered to maintain sufficient reserves of vitamin D in the body. However, certain groups of the population are at greater risk of vitamin D deficiency for a variety of reasons.

If sun exposure is not enough, proper intake through food is especially important. Vitamin D is a fat soluble (fat soluble) vitamin, which is present in varying amounts in foods of animal origin that are high in fat (fish, meat, liver, sometimes in cheese and whole milk). The greatest amounts are found in fatty fish (eg sardines, herring, salmon, mackerel). It is recommended to eat fish, seafood or shellfish once or twice a week, including fatty fish once.

Foods of plant origin can be fortified with vitamin D, as provided by law for vegetable minarines and margarines.
Once in the body, vitamin D must undergo an initial reaction in the liver, then in the kidneys, before it is fully active. It is therefore essential that the liver and kidneys function properly.

In certain situations at risk of vitamin D deficiency, supplements are advised. These include, for example, infants who are only breastfed, children under 3 years of age with dark skin, children treated with anti-epilepsy drugs and the elderly, especially if they live in an institution.

What can your doctor do?

It is important that your GP first determines the cause of the hypocalcaemia. Mild complaints associated with calcium deficiency can be relieved with medication, for example calcium carbonate. Sometimes hospital treatment is needed (via an infusion directly into the blood). The administration of calcium is often supplemented by vitamin D.

Always discuss calcium and vitamin D intake with your doctor.

If the calcium deficiency is due to abnormal functioning of the parathyroid glands, you will be referred to a specialist (endocrinologist).

Want to know more?

• Eating and gaining years of life is possible! (video) – CSS – Superior Health Council
• The food pyramid – Eat Move – Health Question

Sources

• Foreign clinical practice guide ‘Hypocalcemia, hypoparathyroidism and vitamin D deficiency’ (2000), updated on 12.09.2017 and adapted to the Belgian context on 15.12.2017 – ebpracticenet
• Vitamin D and derivatives – CBIP – Belgian Center for Pharmacotherapeutic Information
• Nutritional recommendations for Belgium – Superior Health Council (2016)
• Dietary recommendations for the adult Belgian population – Superior Health Council (2019)