Fluid & Electrolyte Q 6

---

For a patient with hypomagnesemia, which of the following medications may become toxic?

  

    A. Lasix

    B. Digoxin

    C. Calcium gluconate

    D. CAPD

    

    

Correct Answer: B. Digoxin

---

In hypomagnesemia, a patient on digoxin is likely to develop digitalis toxicity. Magnesium deficiency was the most frequently identified significant electrolyte disturbance in relation to digoxin toxicity. In the presence of magnesium deficiency digoxin toxicity developed at relatively low serum digoxin concentrations. Neither A nor C has toxicity as a side effect.

---

Option A: Loop diuretics (including furosemide, bumetanide, and ethacrynic acid), produce large increases in magnesium excretion through the inhibition of the electrical gradient necessary for magnesium reabsorption in the TAL. Long-term thiazide diuretic therapy also may cause magnesium deficiency, through enhanced magnesium excretion and, specifically, reduced renal expression levels of the epithelial magnesium channel TRPM6.

Option C: Calcium gluconate may reverse many of the magnesium-induced changes, including respiratory depression. Administration of IV furosemide can increase magnesium excretion when renal function is adequate; volume status should be maintained.

Option D: CAPD is not a medication. CAPD, (Continuous Ambulatory Peritoneal Dialysis), is a way of artificially removing the waste fluid and poisons from the body by using the abdominal membrane as a filter. The treatment involves putting special dialysis fluid into this cavity, usually four times per day.

---