The Importance of Urinary Magnesium Values in Patients With Gut Failure

To determine whether urinary magnesium (Mg) values in patients with gut failure would be more helpful than serum Mg measurements in assessment of Mg deficiency. We compared serum and urinary Mg values in 16 patients with gut failure and 16 age- and sex-matched control subjects. Sixteen patients with gut failure (nine women and seven men; mean age, 59 years) had serum and 24-hour urinary Mg measured before Mg replacement therapy. Short bowel syndrome was present in 75%, and diffuse small bowel disease was present in 25%. The median value for serum Mg was 1.7 mg/dL for patients and 2.0 mg/dL for healthy control subjects (P