Blood magnesium level – test

Blood magnesium level

Magnesium is primarily an intracellular ion. Around 60% of the body’s magnesium stores are found in the bones and 38% in soft tissues (the liver and skeletal muscles). The magnesium measured in the blood accounts for just 2% of the body’s stores. After the age of 60, the amount of this element in tissues changes, decreasing to 60-80% of the levels observed in children’s tissues.

Magnesium plays a key role in many of the body’s energy processes, which underpin synthesis reactions and many other cellular activities. Magnesium is present in every cell in the body. It is an element essential for energy production, muscle contraction, nerve function and maintaining bone mass. Around half of the body’s magnesium stores, together with calcium and phosphorus, form the building blocks of bones.

Magnesium is involved in a range of processes:

— it affects neuromuscular excitability (reduces the excitability of nerve cells);

— it has anti-atherosclerotic and antithrombotic effects (stabilises platelet membranes and reduces their tendency to aggregate, which reduces the tendency for clots to form along blood vessel walls); protects the heart against a lack of oxygen and an inadequate blood supply; reduces spasms in blood vessels;

— it affects bone hardness (ensures normal bone mineralisation and development, and accelerates bone remodelling)

— it supports liver function and is involved in the synthesis of enzymes and digestive juices

— it increases sperm viability and motility, has a beneficial effect on foetal development, and is a key element in activating and regulating cell reproduction

— it stimulates the body’s defence mechanisms (supports the treatment of infections)

— it is essential for the synthesis, absorption and release of certain hormones (adrenaline, parathyroid hormone, calcitonin, insulin).

Many foods, particularly green vegetables such as spinach, as well as grains and nuts, contain small amounts of magnesium, and most of this element in the body comes from the diet. Magnesium requirements vary. In adults, they range from 300 to 350 mg a day. Requirements are slightly higher in adolescents, pregnant or breastfeeding women, and people exposed to chronic stress, ranging from 400 to 700 mg a day. You can supply your body with magnesium by eating a variety of foods, from fish (cod, pollock, mackerel), fruit (bananas) and dried seeds to vegetables (spinach, sweetcorn, pulses), cocoa and chocolate.

The body maintains a constant magnesium level in the blood, cells and bones by regulating its absorption in the intestines and excretion through the kidneys. Magnesium absorption is adversely affected by an alkaline environment, plant proteins, saturated fats, fatty acids that form insoluble compounds with magnesium, phytic acid (cereals), oxalic acid (rhubarb, spinach, sorrel), excess calcium (consuming dairy products at the same time), alcohol and certain medicines (high doses of laxatives, diuretics and antibiotics). Drinking beverages buffered with phosphoric acid (such as Coca Cola) is also unfavourable, as they form insoluble magnesium salts. Factors that promote magnesium absorption include a more acidic environment, a diet rich in animal proteins, unsaturated fats, vitamin B6, sodium, lactose and vitamin D.

Magnesium is excreted mainly through the kidneys, and this renal excretion regulates the magnesium content of the blood — urinary excretion increases when there is excess magnesium and decreases when there is a deficiency.

The reference range for blood magnesium is 0.65–1.2 mmol/l

A low blood magnesium level (hypomagnesaemia) may indicate:

1. insufficient magnesium in the diet,
2. impaired magnesium absorption in the digestive tract,
3. excessive magnesium excretion through the kidneys.

The effects of magnesium deficiency are usually easy to notice. They include disturbances of neuromuscular excitability (muscle cramps, muscle tremors, episodes of tetany), skeletal disorders (osteoporosis, cartilage calcification), cardiovascular disorders (palpitations, arrhythmia, hypertension, myocardial ischaemia, atherosclerosis, increased blood clotting), digestive disorders (reduced appetite, vomiting, diarrhoea), reproductive system disorders (menstrual disturbances), and allergies. General symptoms may include depressive symptoms, drowsiness, hallucinations, sleep disturbances, irritability, anxiety, weakness, fatigue, headaches and nausea.
Deficiency may be caused by:

• Inadequate intake (in older people, malnutrition or alcoholism)
• The toxicity of certain substances (excessive tea drinking, caffeine intoxication, alcoholism);
• Low magnesium intake (parenteral nutrition, fasting, malnutrition, unbalanced or low-energy diets);
• Digestive tract diseases (e.g. Crohn’s disease)
• Poorly controlled diabetes
• Hypoparathyroidism
• Long-term use of diuretics
• Chronic diarrhoea
• A postoperative state
• A severe burn
• Pre-eclampsia

Medicines that lower magnesium levels include digoxin, ciclosporin, diuretics, insulin, certain antibiotics, laxatives and phenytoin.

A raised blood magnesium level rarely results from excessive dietary intake; it is usually caused by impaired magnesium excretion or excessive supplementation.

A raised magnesium level (above 1.2 mmol/l) occurs in:

• Kidney failure
• Hyperparathyroidism
• Hypothyroidism
• Dehydration
• Diabetic acidosis
• Addison’s disease
• Overuse of antacids or laxatives containing magnesium

Medicines that increase magnesium levels include lithium, aspirin, thyroid hormones, certain antibiotics and products containing magnesium.

The effects of an increased blood magnesium level include constipation, urinary retention due to muscle paralysis, reduced blood pressure and muscle weakness.

Magnesium is an important trace element for the body, performing a range of functions that help maintain homeostasis. Given the importance of the magnesium ion, you should take care to obtain an adequate daily amount of magnesium to prevent a deficiency of this element. Its level in the body can be checked by collecting blood from a vein at the elbow on an empty stomach.

* If your results fall outside the reference range, we recommend consulting a doctor. The result report is issued in Polish.

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