Magnesium Deficiency and Hypocalcemia

Diagnosis and Treatment

The American College of Cardiology recommends measuring ionized calcium corrected by pH to diagnose hypocalcemia, and verifying magnesium levels in all hypocalcemic patients, as hypomagnesemia must be corrected first 1, 2
The normalization of calcium levels requires approximately 4 days after initiating magnesium therapy, even when parathyroid hormone (PTH) levels normalize within 24 hours 2
For symptomatic acute hypocalcemia with hypomagnesemia, administer 1-2 g of magnesium sulfate IV bolus 3
Supplementation of magnesium is necessary if hypomagnesemia is present, and calcium and phosphorus levels should be monitored at least every 3 months during treatment 2

Less than 1% of the body's total magnesium is in extracellular fluids, so patients can have magnesium deficiency despite normal serum concentrations 2
Magnesium acts as an important cofactor for multiple enzymes, including ATPase, and is necessary for the movement of sodium, potassium, and calcium in and out of cells 3
The European Society of Cardiology recommends not administering calcium without first correcting magnesium, as it will be ineffective 1
Overcorrection of calcium can lead to hypercalcemia, kidney stones, and renal failure 2, 4