Magnesium is one of the essential minerals in the human organism. The daily coverage of an adult is 300 mg, which is supplied mainly through vegetable food. Plenty of biochemical reactions in the human organism cannot take place without magnesium. One of the most important is the provision of energy through adenosine triphosphate (ATP), which is activated by magnesium. A deficiency of magnesium caused by environmental, illness, dietary and medication-related factors can lead to disorders in the human body. Muscle cramps are one of the most common symptoms caused by a lack of magnesium. The interaction of magnesium and calcium is particularly important. A magnesium deficiency forwards a demineralization of the skeleton. Furthermore, magnesium inhibits the formation of calcium oxalate and thus the production of nephroliths. If a deficiency is suspected, it is important to determine the magnesium level in the blood so that the symptoms can be corrected quickly.