Chapter 24: Plasma Magensium, Hypomagnesemia, and Hypermagnesemia

Question 1

Plasma Manesium

Answer 1

• normal = 1.5 to 2.5 mEq/L

- magnesium ions present in bound and unbound forms

Question 2

Hypomagnesemia

Answer 2

• serum magnesium concentration below the lower limit of mormal (1.5 mEq/l)

Question 3

Etiology of Hypomangesemia

Answer 3

• Decreased magnesium intake or absorption: chronic alcoholism, malnutrition, ileal resection
• decreased physiologic availability of magnesium: elevated plasma free fatty acids
• increased magnesium excretion: usually renal
• loss of magnesium by an abnormal route: emesis

Question 4

Clinical Manifestations of Hypomagnesemia

Answer 4

• increased neuromuscular excitability from excessive amount of acetylcholine which causes
• insomnia
• hyperactive reflexes
• muscle cramps
• muscle twitching, grimacing
• positive Chvostek sign
• positive trousseau sign
• nystagmus
• dysphagia
• tetany
• seizures
• cardiac dysrhythmias

Question 5

Hypermagnesemia

Answer 5

• serum magnesium concentration above the upper limit of normal (2.5 mEq/L)

Question 6

Etiology of Hypermagnesemia

Answer 6

• increased magnesium intake or absorption: laxatives. antacids
• decreased magnesium excretion: oliguric renal failure, adrenal insufficiency

Question 7

Clinical Manifestations of Hypermagnesemia

Answer 7

• Depression of neuromuscular function related to decreased released of acetylcholine at neuromuscular junction causes
• decreased deep tendon reflexes
• lethargy
• hypotension
• flushing
• diaphoresis
• drowsiness
• flaccid paralysis
• Bradycardia
• cardiac dysrhythmias
• cardiac arrest