Test Details: Magnesium is a major intracellular cation and an important cofactor of many enzyme systems. This test aids in assessing the cause of abnormal serum magnesium concentrations using a 24-hour urine collection. High levels of plasma magnesium are typically seen in patients with decreased renal function, whereas hypomagnesemia is observed in patients consuming medications which can cause interference with magnesium absorption, or in patients suffering from gastrointestinal diseases such as celiac disease, Inflammatory bowel disease.