Magnesium imbalances

what is the rank of magnesium among intracellular cations in terms of abundance

2nd most abundant

What are some key cellular processes magnesium is involved in?

carbohydrate metabolism, DNA and protein synthesis, blood glucose control, BP regulation, and ATP production/use

what role does magnesium play in muscle and neurologic function?

it is essential for muscle contraction and relaxation, normal neurologic function, and neurotransmitter release

where is most of the body’s magnesium stored?

50-60% is stored in muscle and bone, 30% in cells and 1% in ECF

how is magnesium regulated in the body?

through GI absorption and renal reabsorption; both increase when magnesium levels are low

where in the nephron is magnesium reabsorbed?

in the ascending loop of Henle and distal tubules

What is the most common hypermagnesemia?

increased magnesium intake in patients with renal insufficiency or failure

what common over-the-counter products can cause hypermagnesemia in patients with kidney disease?

Maalox, Milk of Magnesia, magnesium-containing laxatives and antacids

What medical treatment in pregnant women can lead to hypermagnesemia?

magnesium sulfate for treatment of eclampsia

how does excess magnesium affect nerve and muscle function?

it inhibits acetylcholine release and calcium movement into cells, impairing function

what are early signs of hypermagnesemia?

hypotension, facial flushing, lethargy, urinary retention, n/v

what are late/severe signs of hypermagnesemia

loss of deep tendon reflexes, muscle paralysis, coma, respiratory arrest, cardiac arrest

what is the first step in managing hypermagnesemia?

stop magnesium-containing drugs and limit dietary magnesium intake

how is magnesium excreted if renal function is adequate?

by increasing fluids and using diuretics

what treatment is required for hypermagnesemia in patients with renal failure?

dialysis

what is used to reverse the effects of severe hypermagnesemia on the heart?

IV calcium gluconate

what are major causes of hypomagnesemia?

limited magnesium intake, GI losses, and renal losses

which conditions can lead to decreased magnesium intake

prolonged fasting or starvation, chronic alcohol use, and prolonged parenteral nutrition without magnesium

what are GI related causes of hypomagnesemia?

fluid loss from GI tract, acute pancreatitis, and poorly controlled diabetes

which medications can contribute to hypomagnesemia?

diuretics, proton pump inhibitors, and some antibiotics

what neuromuscular signs are seen in hypomagnesemia?

muscle cramps, tremors, hyperactive deep tendon reflexes, Chvostek sign, Trosseau sign

what neurologic symptoms are associated with hypomagnesemia?

confusion, vertigo, and seizures

what cardiac dysrhythmias are linked to hypomagnesemia?

Trades de pointes and ventricular fibrillation

how is mild hypomagnesemia treated?

with oral magnesium supplements and increased dietary intake

when is IV magnesium given?

for severe hypomagnesemia or when hypocalcemia is also present