Dig, K, and Mag levels

mommatrauma, RN · Jul 26, 2005

Digoxin decreases intracellular magnesium, thereby causing increased urinary magnesium loss. Magnesium deficiencies induced by concomitant diuretic use are very common in individuals using digoxin. Hypomagnesemia may predispose to digitalis toxicity.

(Toffaletti J. Analyt Chem 1991 63(12):192R-194R; al-Ghamdi SM, et al. Am J Kidney Dis 1994 Nov;24(5):737-752.)

* clinical implications: Hypomagnesemia is known to produce a wide variety of clinical presentations, including neuromuscular irritability, cardiac arrhythmias, and increased sensitivity to digoxin. Magnesium deficiency also inhibits the therapeutic efficacy of digoxin in controlling atrial fibrillation. Refractory hypokalemia and hypocalcemia can be caused by concomitant hypomagnesemia and can be corrected with magnesium therapy.

(Toffaletti J. Analyt Chem 1991 63(12):192R-194R; Young IS, et al. Br J Clin Pharmacol. 1991 Dec;32(6):717-721; Lewis R, et al. Br J Clin Pharmacol. 1991 Feb;31(2):200-203.)

* testing: Many physicians are aware of the need to monitor and prescribe for potassium depletion but do not consider the issue of magnesium deficiency unless serum levels fall below acceptable levels. Furthermore, many physicians experienced in nutritional assessment consider serum magnesium to be a very poor indicator of how much magnesium is actually in the tissues. Serum magnesium concentration is maintained within a narrow range by the kidney and small intestine since under conditions of magnesium deprivation both organs increase their fractional absorption of magnesium. If magnesium depletion continues, the bone store contributes by exchanging part of its content with extracellular fluid (ECF). The serum Mg can be normal in the presence of intracellular Mg depletion, and the occurrence of a low level usually indicates significant magnesium deficiency. Hypomagnesemia is frequently encountered in hospitalized patients and is seen most often in patients admitted to intensive care units. The detection of magnesium deficiency can be increased by measuring magnesium concentration in the urine or using the parenteral magnesium load test.

(al-Ghamdi SM, et al. Am J Kidney Dis 1994 Nov;24(5):737-752; Marz R. 1997.)

* nutritional support: Individuals taking digoxin will almost always benefit from supplementation of magnesium. Studies and clinical experience indicate that 300-500 mg of magnesium per day would be an appropriate dosage level for supplementing such patients. Anyone taking digoxin should consult the prescribing physician and/or a nutritionally-oriented healthcare professional regarding the issue of magnesium supplementation.

(Kinlay S, Buckley NA. J Toxicol Clin Toxicol 1995;33(1):55-59; Sueta CA, et al. Magnes Res 1995 Dec;8(4):389-401.)

nutrients affected by drug: Potassium

* mechanism: Potassium deficiency induced by concomitant diuretic use are very common in individuals using digoxin, often being secondary to hypomagnesia. Hypokalemia may predispose to digitalis toxicity.

* nutritional support: Individuals taking digoxin will often benefit from increasing their intake of potassium. Many physicians who prescribe digoxin monitor for potassium depletion and prescribe potassium supplements when measurable deficiencies are found. However direct supplementation of potassium may not be appropriate since potassium pills are limited to dosages of 99 mg each and taking several at a time may cause digestive irritation. Adequate dietary potassium can easily be obtained by eating several pieces of fruit each day; for example, one banana typically provides 500 mg. Other research, including that by Schmidt et al, indicates that the impairment of extrarenal potassium homeostasis by heart failure and digoxin treatment may be counterbalanced by exercise. Anyone taking digoxin should consult the prescribing physician and/or a nutritionally-oriented healthcare professional regarding the issue of potassium supplementation.

(Schmidt TA, et al. Cardiovasc Res 1995 Apr;29(4):506-511.)

http://home.caregroup.org/clinical/altmed/interactions/Drugs/Digoxin.htm

VickyRN, MSN, DNP, RN · Jul 26, 2005

Digoxin decreases intracellular magnesium, thereby causing increased urinary magnesium loss. Magnesium deficiencies induced by concomitant diuretic use are very common in individuals using digoxin. Hypomagnesemia may predispose to digitalis toxicity.
(Toffaletti J. Analyt Chem 1991 63(12):192R-194R; al-Ghamdi SM, et al. Am J Kidney Dis 1994 Nov;24(5):737-752.)
* clinical implications: Hypomagnesemia is known to produce a wide variety of clinical presentations, including neuromuscular irritability, cardiac arrhythmias, and increased sensitivity to digoxin. Magnesium deficiency also inhibits the therapeutic efficacy of digoxin in controlling atrial fibrillation. Refractory hypokalemia and hypocalcemia can be caused by concomitant hypomagnesemia and can be corrected with magnesium therapy.
(Toffaletti J. Analyt Chem 1991 63(12):192R-194R; Young IS, et al. Br J Clin Pharmacol. 1991 Dec;32(6):717-721; Lewis R, et al. Br J Clin Pharmacol. 1991 Feb;31(2):200-203.)
* testing: Many physicians are aware of the need to monitor and prescribe for potassium depletion but do not consider the issue of magnesium deficiency unless serum levels fall below acceptable levels. Furthermore, many physicians experienced in nutritional assessment consider serum magnesium to be a very poor indicator of how much magnesium is actually in the tissues. Serum magnesium concentration is maintained within a narrow range by the kidney and small intestine since under conditions of magnesium deprivation both organs increase their fractional absorption of magnesium. If magnesium depletion continues, the bone store contributes by exchanging part of its content with extracellular fluid (ECF). The serum Mg can be normal in the presence of intracellular Mg depletion, and the occurrence of a low level usually indicates significant magnesium deficiency. Hypomagnesemia is frequently encountered in hospitalized patients and is seen most often in patients admitted to intensive care units. The detection of magnesium deficiency can be increased by measuring magnesium concentration in the urine or using the parenteral magnesium load test.
(al-Ghamdi SM, et al. Am J Kidney Dis 1994 Nov;24(5):737-752; Marz R. 1997.)
* nutritional support: Individuals taking digoxin will almost always benefit from supplementation of magnesium. Studies and clinical experience indicate that 300-500 mg of magnesium per day would be an appropriate dosage level for supplementing such patients. Anyone taking digoxin should consult the prescribing physician and/or a nutritionally-oriented healthcare professional regarding the issue of magnesium supplementation.
(Kinlay S, Buckley NA. J Toxicol Clin Toxicol 1995;33(1):55-59; Sueta CA, et al. Magnes Res 1995 Dec;8(4):389-401.)
nutrients affected by drug: Potassium
* mechanism: Potassium deficiency induced by concomitant diuretic use are very common in individuals using digoxin, often being secondary to hypomagnesia. Hypokalemia may predispose to digitalis toxicity.
* nutritional support: Individuals taking digoxin will often benefit from increasing their intake of potassium. Many physicians who prescribe digoxin monitor for potassium depletion and prescribe potassium supplements when measurable deficiencies are found. However direct supplementation of potassium may not be appropriate since potassium pills are limited to dosages of 99 mg each and taking several at a time may cause digestive irritation. Adequate dietary potassium can easily be obtained by eating several pieces of fruit each day; for example, one banana typically provides 500 mg. Other research, including that by Schmidt et al, indicates that the impairment of extrarenal potassium homeostasis by heart failure and digoxin treatment may be counterbalanced by exercise. Anyone taking digoxin should consult the prescribing physician and/or a nutritionally-oriented healthcare professional regarding the issue of potassium supplementation.
(Schmidt TA, et al. Cardiovasc Res 1995 Apr;29(4):506-511.)
http://home.caregroup.org/clinical/altmed/interactions/Drugs/Digoxin.htm

Great information! Thanks :)

Home Health Columnist / Guide · Jul 26, 2005

Thanks mommatrauma for sharing above + great website for info!!

Great example of knowledge = power.