hypermagnesemia Flashcards
Q: What does hypermagnesemia mean?
A: Hypermagnesemia means higher than normal magnesium levels in the blood, typically over 4 mEq/L.
Q: How much magnesium does an average adult have in their body?
A: An average adult has about 25 grams of magnesium in their body.
Q: Where is most of the body’s magnesium stored?
A: About half is stored in the bones, and most of the other half is within cells.
Q: What fraction of total body magnesium is found in the extracellular space?
A: About 1% of the total magnesium is in the extracellular space.
Q: How is magnesium distributed in the extracellular space?
A: About 20% is bound to proteins like albumin, and 80% is filterable by the kidneys.
Q: How much magnesium gets reabsorbed at different parts of the nephron?
A: 30% at the proximal convoluted tubule, 60% at the ascending loop of Henle, and 5% at the distal convoluted tubule.
Q: What causes hypermagnesemia in renal failure?
A: The kidneys cannot excrete magnesium properly, leading to its accumulation in the blood.
Q: How can excessive intake lead to hypermagnesemia?
A: Ingesting more magnesium than the kidneys can excrete, such as from magnesium-containing medications or incorrect IV infusions.
Q: What is tumor lysis syndrome?
A: It results from rapid cell death in cancers, releasing intracellular contents including magnesium into the blood.
Q: How does hypermagnesemia affect neuromuscular function?
A: Excess magnesium inhibits calcium influx at the neuromuscular junction, slowing neurotransmitter release and muscle contraction.
Q: How does hypermagnesemia cause hypocalcemia?
A: High magnesium inhibits parathyroid hormone release, lowering calcium levels in the blood.
Q: What cardiac complications can hypermagnesemia cause?
A: High magnesium levels can alter cardiac cell membrane potential, leading to arrhythmias like heart block and asystole.
Q: At what magnesium level do symptoms of hypermagnesemia usually appear?
A: Symptoms typically appear when magnesium levels exceed 4 mEq/L.
Q: How is hypermagnesemia treated if due to excessive intake?
A: Interrupting the source of magnesium intake cures the condition.
Q: What role does calcium play in treating hypermagnesemia?
A: Injecting calcium, usually as calcium gluconate, acts as a physiological antagonist to counter some symptoms of hypermagnesemia.
