What is Magnesium Deficiency? (Introduction)

Magnesium deficiency, also called hypomagnesaemia, means the level of magnesium in the blood is lower than normal. Magnesium is a mineral the body needs for many tasks.

What magnesium does

• Helps muscles and nerves work, including the heart muscle
• Helps make energy and protein
• Helps control blood sugar and blood pressure
• Works with calcium and potassium to keep nerves and muscles stable
• Supports bone strength

How common is it

Low blood magnesium is uncommon in healthy people with a balanced diet, because the kidneys save magnesium when intake is low. It is more common in people who drink a lot of alcohol, have long-term diarrhoea or gut disease, have diabetes, or take certain medicines such as diuretics or acid-reducing medicines. It is also seen in hospital patients who are unwell.

Mild versus significant deficiency

Mild deficiency may cause no symptoms. A significant deficiency can cause cramps, tremor, weakness, abnormal heart rhythm and seizures. Low magnesium often comes with low potassium and low calcium, which are hard to correct until magnesium is replaced.

Normal levels

Blood magnesium is commonly around 0.7 to 1.0 mmol/L (1.7 to 2.4 mg/dL), but ranges vary by laboratory. Blood tests show only a small part of the body's total stores.

Ayurvedic view

Ayurveda does not describe magnesium as a nutrient, but it links muscle cramps, weakness and tremor to Vata imbalance. This is a traditional view and not a modern diagnosis.

Key point

Low magnesium usually has a clear cause. Finding and treating the cause matters as much as replacing the mineral.

Before your appointment

Note your symptoms, when they began, and what makes them better or worse. Mention alcohol use, diarrhoea, vomiting, diabetes, kidney disease, bowel conditions and any recent illness. List all medicines, especially diuretics, acid-reducing medicines, antibiotics, supplements and herbal products. Write down your usual diet and any antacids or laxatives you take. Ask about blood tests for magnesium, potassium and calcium, and whether an ECG is needed. Call 112 for seizures, fainting, severe weakness or a very irregular heartbeat.