     contributes to hypokalemia and suboptimal potassium metabolism.


While it is certainly important to note how often potassium and magnesium are found together in human physiology and how often low levels are found together in various disease states, it may be even more important to point out that there is a cause and effect aspect to this relation- ship that goes beyond mere association. This cause and effect relationship has been emphasized in two papers I have located.


between disorders of K


Solomon (Solomon R. Sem Nephrology, Vol. 7, No. 3, pp. 253-262, September 1987). Two quotes from this paper make it clear that magnesium deciency must be addressed whenever efforts are being made to replete potassium: “…tissue content of potassium also decreases with magnesium depletion. This potassium depletion occurs rapidly and may or may not be accompanied by a decrease in serum potassium. The degree of potassium depletion and the effect on serum potassium depends in part on the amount of potassium provided in the diet of the  of both dietary potassium and magnesium results in the greatest potassium depletion (greater than that seen with         hypokalemia.”


The rst is entitled “The relationship and Mg


homeostasis” by


Why might magnesium deciency affect potassium levels  transport of potassium into the cell.”


Then, in the conclusion, Solomon provides more detail on how magnesium deciency adversely affects potassium physiology: “…primary disturbances in magnesium balance, particularly magnesium depletion, produce secondary potassium depletion. This appears to result from an inability of the cell to maintain the normally high intracellular concentration of potassium, perhaps as a result of an increase in membrane permeability to potassium and/or inhibition of Na+-K-ATPase. As a result, the cells lose potassium, which is excreted in the urine. Repletion of cell potassium requires correction of 


The second paper I found that addresses the impact of magnesium deciency on potassium metabolism is “Mechanism of hypokalemia in magnesium deciency” by Huang and Kuo (Huang CL & Kuo E. J Am Soc Nephrol, Vol. 18, pp. 2649-2652, 2007). As you will see from the following selection of quotes from this paper, it is well established that optimal levels of magnesium are necessary for optimal potassium metabolism. First, consider the following: “It is estimated that more than  


Furthermore, this relationship is not just a statistical association but a major cause and effect phenomenon:       appreciated to aggravate hypokalemia.”


Because of this, correcting magnesium deciency is essen- 42


tial for addressing hypokalemia: “Co-administration of magnesium is essential for correcting the hypokalemia.”


The next few quotes provide more detail on the biochemistry of this cause and effect issue: “Previous articles suggested that impairment of Na-K-ATPase       +       which would decrease cellular uptake of K+


.”


is excreted by the gastrointestinal tract normally; therefore, hypokalemia in magnesium deciency is likely associated with enhanced renal K


In addition: “Little K


levels in a patient with Bartter disease with combined hypomagnesemia and hypokalemia. Similarly, magnesium replacement alone (without K serum K


is these individuals. Moreover, magnesium infusion decreases urinary K


excretion in normal individuals.”


One reason that magnesium supplementation decreases loss of potassium in the urine is its impact on renal function: “Thus, magnesium replacement prevents renal K+


To conclude their paper, Huang and Kuo state the following: “Magnesium and K+


effects of hypokalemia on target tissues. Recognition of      with magnesium are imperative for effective treatment and prevention of complications of hypokalemia.”


       


As you can see, there is a wealth of data which suggests that magnesium deciency can cause or contribute to potassium deciency. Can the reverse by true where potassium deciency contributes to or causes magnesium deciency Unfortunately, I could only nd one reference to this relationship in the medical literature. According to Quamme and DeRoufgnac (Quamme GA & DeRoufgnac C. Renal magnesium handling, in Selden DW & Giebisch G eds., The Kidney: Physiology & Pathophysiology, Volume II, Third Edition, Lippincott Williams Wilkins, Philadelphia, 2000, pp. 1711-1729): “Hypokalemia and potassium depletion is associated with diminished magnesium absorption with the loop and distal tubule, which may lead to increased magnesium excretion.”


Is this important interrelationship between potassium


THE ORIGINAL INTERNIST MARCH 2017 (Continued on page 46)


for stabilizing membrane potential and decreasing         exacerbate K+


wasting but also aggravate the adverse


intracellular cations. Because of their predominant        under recognized. Both magnesium and K+


are critical are the two most abundant


wasting, at least in part, by decreasing secretion in the distal nephron.”


levels in individuals who have hypokalemia and hypomagnesemia and receive thiazide treatment. Magnesium administration decreased urinary K


excretion ) increases


this idea, Baehler et al. showed that administration of magnesium decreases urinary K serum K


excretion. To support excretion and increases


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52