Magnesium deficiency is often associated with refractory hypokalemia (In up to 50% of cases there is concomitant hypomagnesemia).
WHY? Exact mechanism isn’t known for certain.
PROPOSED MECHANISM: Low intracellular magnesium causes renal wasting of potassium. Normally magnesium will inhibit Renal Outer Medullary Potassium (ROMK) channels in the kidneys; however, hypomagnesemia allows the ROMK channel to efflux K+ into the urine.
NOTE: High Na+ uptake/ aldosterone states may also cause K+ loss (see image).
- Chou-Long Huang and Elizabeth Kuo. Mechanism of Hypokalemia in Magnesium Deficiency. JASN October 2007 vol. 18 no. 10 2649-2652