Hypomagnesemia

Definition

• Serum Mg⁺⁺ <1.8 mg/dL

Etiology:

• Malnutrition (assc. with heavy chronic alcohol use causing renal wasting)
• Malabsorption or diarrhea/GI loss
• PPI induced
• Renal losses (polyuria and high tubular flow, e.g., osmotic diuresis, post-ATN diuresis)
• Hypercalcemia (e.g. hyperparathyroidism)
• Loop and thiazide diuretic associated
• Proximal tubular toxins (e.g. aminoglycosides, amphotericin, cisplatin)
• Calcineurin inhibitors (tacrolimus > cyclosporine)
• Volume expansion (reduced Mg⁺⁺ reabsorption due to reduced Na and H₂O reabsorption)
• Gitleman and Bartter syndromes
• Uncontrolled DM, post-parathyroidectomy (Hungry bone syndrome)

Evaluation:

• Order CMP, serum Mg⁺⁺ and Phosphorus level
• Review patient history, clinical circumstances, nutritional status and medications

Management: