PHRM 825: Fluids and Electrolytes - Electrolytes - Mg+2

Question 1

Normal magnesium blood level

Answer 1

1.5-2.5 mg/dL

Question 2

Magnesium plays an important role in _____ function

Answer 2

neuromuscular

Question 3

Magnesium is a cofactor for which enzymes in the body?

Answer 3

ATPase and alkaline phosphatase

Question 4

Magnesium is needed to stabilize which macromolecular structures

Answer 4

DNA/RNA

Question 5

Magnesium levels are regulated by ____ and ____

Answer 5

intake and kidney excretion

Question 6

Magnesium metabolism is also related to ____ and ___ metabolism

Answer 6

Ca+ and K+

Question 7

Hypomagnesemia is associated with disorders of ____ or ____

Answer 7

the GI tract or kidneys

Question 8

What 5 things can reduce magnesium blood levels?

Answer 8

• Diarrhea
• Decreased GI absorption
• Severe malnutrition
• Drugs
• Alcohol

Question 9

What drugs can cause hypomagnesemia?

Answer 9

• Amphotericin
• Aminoglycosides
• Diuretics (thiazide or loop)

Question 10

Hypomagnesemia is often associated with __ and ___

Answer 10

hypocalcemia and hypokalemia

Question 11

Clinical presentation of hypomagnesemia in the cardiac system

Answer 11

Tetany, generalized convulsions, ventricular cardiac arrhythmias

Question 12

Clinical presentation of hypomagnesemia in the neuromuscular system

Answer 12

Ataxia, fasiculations, seizures

Question 13

Clinical presentation of hypomagnesemia in the CNS

Answer 13

Lethargy, confusion, nystagmus

Question 14

Goals of therapy for hypomagnesemia

Answer 14

• Resolution of symptoms
• Restoration of normal Mg+2 concentration
• Correction of concomitant electrolytes
• Identify and correct underlying cause(s)
• correct underlying electrolyte abnormalities

Question 15

When to treat hypomagnesemia with PO meds

Answer 15

When patients are asymptomatic and Mg+2 levels are >1 mg/dL

Question 16

PO medications used to treat hypomagnesemia

Answer 16

• Milk of mag (magnesium hydroxide suspension) 5-10 mL PO QID
• Mag-ox 800 mg PO daily or 400 mg PO TID with meals

Question 17

When to treat hypomagnesemia with IV meds

Answer 17

When patients are symptomatic or cannot tolerate PO meds

Question 18

IV medications used to treat hypomagnesemia

Answer 18

• Mg+2 1-2 mg/dL: 0.5 mEq/kg
• Mg+2 <1 mg/dL: 1 mEq/kg

8 mEq = 1 g
Infuse at 1 g/hr

Question 19

Hypermagnesemia is ____

Answer 19

VERY rare

Question 20

Causes of hypermegnesemia

Answer 20

• Renal failure or renal insufficiency

- Excessive intake of Mg+2 (via Mg+2 containing laxatives or during treatment for eclampsia)

Question 21

Hypermagnesemia typically starts causing symptoms when Mg+2 is > ___

Answer 21

4 mg/dL

Question 22

Clinical presentation of hypermagnesemia in the neuromuscular system

Answer 22

• Loss of deep tendon reflexes
• Drowsiness, lethargy, somnolence
• Respiratory muscle paralysis

Question 23

Clinical presentation of hypermagnesemia is the cardiovascular system

Answer 23

• Hypotension
• Cardiac rhythm abnormalities
• Complete heart block

Question 24

Goals of therapy for hypermagnesemia

Answer 24

• Reverse the neuromuscular and cardiovascular manifestations
• Decrease the Mg+2 concentration to NL
• Identify and treat the underlying cause

Question 25

Hypermagnesemia treatment for cardiac complications

Answer 25

Calcium chloride 1-2 grams IV x 1 and repeat prn

Question 26

Hypermagnesemia treatment for adequate renal function

Answer 26

• IV hydration with NS or 1/2 NS infused at ~200ml/hr + 1-2 g Ca+
• IV furosemide

Question 27

Hypermagnesemia treatment when renal dysfunction is present

Answer 27

• Forced diuresis

- Hemodialysis

Question 28

Supportive care (as needed) during hypermagnesemia treatment

Answer 28

• Cardiac pacing
• Vasopressors
• Mechanical ventilation