Causes of Chronically Low Magnesium

Gastrointestinal Causes

The American Heart Association notes that chronically low magnesium results from three primary mechanisms: inadequate intake, excessive gastrointestinal losses, or excessive renal losses—with the most common causes being gastrointestinal malabsorption, medication-induced renal wasting, and alcohol use disorder 1.
Short bowel syndrome, particularly in patients with jejunostomy, causes severe and intractable magnesium losses through direct loss in intestinal fluid combined with reduced absorption time 2, 3.

Proton pump inhibitors cause renal magnesium wasting through mechanisms that remain incompletely understood, according to the American College of Gastroenterology 4.
Aminoglycosides, cisplatin, cetuximab, pentamidine, and foscarnet directly damage renal tubular magnesium handling, as stated by the National Kidney Foundation 3.

Primary hyperaldosteronism directly increases renal magnesium excretion, as noted by the Endocrine Society 3.
22q11.2 deletion syndrome is associated with hypoparathyroidism and chronic hypomagnesemia, according to the American Academy of Pediatrics 2, 3.

The National Institute of Diabetes and Digestive and Kidney Diseases states that serum magnesium levels do not accurately reflect total body magnesium status, as less than 1% of total body magnesium is found in the blood 2, 3.
Hypomagnesemia causes refractory hypokalemia and hypocalcemia that will not correct until magnesium is repleted, as magnesium deficiency impairs multiple potassium transport systems and parathyroid hormone secretion, according to the American College of Cardiology 3, 4.