The severity of symptoms is not related directly to the magnesium level. In one study of patients who were severely magnesium depleted, physical findings were present in only 2 of 21 patients. Most causes are related to renal and GI losses. GI losses Malnutrition leads to hypomagnesemia when dietary intake of magnesium is low. Dietary sources include green vegetables, fruits, fish, fresh meat, and cereal.
Alcoholics are classically hypomagnesemic in part due to poor nutrition.
Diabetics who are not receiving magnesium supplements may have dietary deficiencies in magnesium. Malabsorption of magnesium in the ileum results in hypomagnesemia. GI secretions in large amounts may cause hypomagnesemia. Significant losses of magnesium resulting in hypomagnesemia may result from chronic diarrhea, laxative abuse, inflammatory bowel disease, or neoplasm. Primary renal disorders cause hypomagnesemia by decreased tubular reabsorption of magnesium by the damaged kidneys.