Deficiency, magnesium: Lack of magnesium, which can occur because of inadequate intake or impaired intestinal absorption of magnesium. Low magnesium levels are often associated with low calcium and potassium levels because these nutrients interact with each other. Magnesium deficiency causes increased irritability of the nervous system, as evidenced by spasms of the hands and feet, muscular twitching and cramps, spasms of the larynx, and other symptoms. Treatment involves ensuring intake and absorption of the recommended dietary allowances of magnesium, currently 420 mg per day for men and 320 mg per day for women. One should not take more than 350 mg per day in supplement form, however.