Mechanism of Hypokalemia in Magnesium Deficiency

Pathophysiological Mechanisms

• Hypomagnesemia-induced secondary hyperaldosteronism increases renal retention of sodium at the expense of magnesium and potassium, which are lost in high amounts in urine 1

Clinical Implications

• To correct hypokalemia in patients with magnesium deficiency, sodium/water depletion must first be corrected to avoid hyperaldosteronism, followed by magnesium repletion 1

Associated Electrolyte Abnormalities

• Hypocalcemia often accompanies hypomagnesemia and hypokalemia because hypomagnesemia impairs parathyroid hormone release 1

Treatment Implications

• When treating hypokalemia, serum magnesium should be measured and corrected if low 2
• For cardiac arrhythmias associated with hypomagnesemia, IV magnesium 1-2 g bolus is recommended regardless of measured serum levels 3
• For mild hypomagnesemia, oral magnesium oxide at a dose of 12-24 mmol daily is recommended 2