Quiz 12: Potassium and Magnesium

potassium

What is the primary intracellular cation?

potassium's major physiologic roles

-maintains resting membrane potential

-regulates intracellular osmolality and acid base balance

-supports protein and glycogen synthesis within cells

-affects cardiac conduction and rhythm

Magnesium

cofactor for > 300 enzymatic reactions including those involved in ATP synthesis and use

Magnesium's major physiologic roles

-regulates neuromuscular excitability by influencing calcium and potassium transport

-stabilizes cell membranes and nucleic acids

-essential for PTH secretion and action, affecting calcium balance

-involved in DNA and protein synthesis and energy metabolism

-muscle weakness, cramping, fatigue

-constipation, ileus

-ECG changes: flattened T waves, U waves and arrythmias

-severe cases: paralysis, respiratory failure, rhabdomyolysis

What are the symptoms associated with disturbances of hypokalemia?

-muscle weakness or flaccid paralysis

-ECG changes: peaked T waves, widened QRS, possible cardiac arrest

-Paresthesias (tingling)

What are the symptoms associated with disturbances of hyperkalemia?

-neuromuscular irritability: tremors, muscle cramps, tetany, seizures

-cardiac arrythmias

-personality changes or confusion

What are the symptoms associated with disturbances of hypomagnesemia?

-lethargy, confusion, diminished reflexes

-hypotension, bradycardia

-muscle weakness, respiratory depression

-severe cases: cardiac arrest

What are the symptoms associated with disturbances of hypermagnesemia?

-pts on diuretics (loops/thiazides)

-CKD or AKI

-Diabetics

-GI loss

-HF or RAAS inhibitor therapy

What are the patient populations who are most likely to have disturbances with potassium?

-alcohol use disorder

-malnutrition or malabsorption

-prolonged diarrhea or vomiting

-diuretic therapy

-uncontrolled diabetes

-CKD

What are the pt populations who are most likely to have disturbances with magnesium?

decreases

Aldosterone _________ potassium

decreases

Insulin _________ potassium

decreases

Catecholamines (B2-adrenergic) ___________ potassium

decreases

Aldosterone __________ magnesium

decreases

Insulin __________ magnesium

decreases

Catecholamines (B2 adrenergic stimulation) ___________ magnesium

increases

PTH __________ magnesium

increases

Vasopressin (ADH) _________ magnesium

increases both

CKD does what to potassium and magnesium?

increases both

AKI does what to potassium and magnesium?

decreases both

DM does what to potassium and magnesium?

decreases both

HF does what to potassium and magnesium?

decreases both

GI loss does what to potassium and magnesium?

decreases both

Alcoholism/Malnutrition does what to potassium and magnesium?

decreases both

Primary Hyperaldosteronism does what to potassium and magnesium?

increases both

Adrenal Insufficiency does what to potassium and magnesium?

hypokalemia (increased urinary loss)

What do loop diuretics do to potassium?

hyperkalemia (decreased excretion)

What do potassium sparing diuretics do to potassium?

hyperkalemia (decreased aldosterone activity)

What do ACE/ARBs/ARNIs and NSAIDs do to potassium?

hypokalemia (shift into cells)

What do Insulin, B-agonist do to potassium?

hypokalemia (mineralocorticoid effect)

What do corticosteroids do to potassium?

hypokalemia (renal tox)

What do aminoglycosides, Amphotericin B, and Cisplatin do to potassium?

Hypomagnesemia (increased urinary loss)

What do Loop and thiazide diuretics do to magnesium?

Hypermagnesima or neutral

What do potassium-sparing diuretics do to magnesium?

hypermagnesemia or neutral

What do ACE/ARBs/ARNI or NSAIDs do to magnesium?

hypomagnesemia (shift into cells)

What do Insulin, B agonists do to magnesium?

hypomagnesmia (renal wasting)

What do corticosteroids do to magnesium?

hypomagnesemia (renal MG wasting)

What do aminoglycosides, Amphotericin B, Cisplatin do to magnesium?

hypomagnesemia (reduced intestinal absorption)

What do proton pump inhibitors do to magnesium?

3.5

Hypokalemia is defined as a serum potassium concentration less than __________ mEq/L.

-cramping

-weakness

-severe cases: paralysis

What are the neuromuscular symptoms of hypokalemia?

-ST depression

-flattened T waves

-elevated U waves

What are the typical ECG changes in hypokalemia?

-atrial flutter

-VF

-heart block

What are the arrhythmias in hypokalemia?

renal and extrenal

A 24-hour urine potassium test can help differentiate between __________ and __________ causes of potassium loss.

hypomagnesmia

Concomitant __________ deficiency often leads to refractory hypokalemia and must be corrected.

10-20

For IV potassium replacement, the maximum recommended infusion rate is __________ to __________ mEq per hour with ECG monitoring.

2.5

Hyperkalemia is defined as a serum potassium concentration greater than __________ mEq/L.

peaked

Early ECG changes in hyperkalemia include __________ T waves.

-QRS widening

-PR prolongation

-loss of P waves

What are the ECG changes that may progress with worsening hyperkalemia?

VT and VF

Severe hyperkalemia can lead to a sine-wave pattern and fatal arrhythmias such as __________ and __________.

calcium

The first priority in treating severe hyperkalemia with ECG changes is administration of intravenous __________.

1 g

The usual dose of IV calcium gluconate for cardiac stabilization is:

-IV Insulin with Dextrose

-Inhaled Albuterol

-IV Bicarbonate (if metabolic acidosis is present)

What therapies shift potassium into cells?

loop diuretics

What diuretics are used in potassium removal?

GI potassium binders like Patriomer and Sodium Zirconium Cyclosilicate

What binders are used in potassium removal?

dialysis

How is potassium removed in refractory cases?

1.7-2.3

Normal serum magnesium concentration is __________ to __________ mg/dL.

1.7

Hypomagnesemia is defined as a serum magnesium level less than __________ mg/dL.

-tremors

-tetany

-seizures

What are the neuromuscular symptoms that may be caused by severe hypomagnesmia?

-prolonged QT interval

-widened QRS

-arrythmias (torsades)

What are the ECG changes in hypomagnasemia?

-diarrhea

-malabsorption

-chronic alcohol use

What are the common GI causes of hypomagnesemia?

-loop diuretics

-thiazide diuretics

-amphotericin B

-Cisplatin

-Aminoglycosides

-Cyclosporin/Tacrolimus

What are the renal causes of hypomagnesemia?

1-2 g

For moderate to severe symptomatic hypomagnesemia, intravenous magnesium sulfate is given in doses of _______ over 1 hr.

concomitant potassium deficiency

often prevents successful correction of hypokalemia in patients with hypomagnesemia

2.3

Hypermagnesemia is defined as a serum magnesium concentration greater than __________ mg/dL.

-N

-flushing

-lethargy

Symptoms of mild hypermagnesemia (2.5-4 mg/dL) may include:

-hypotension

-diminished deep tendon reflexes

-somnolence

Symptoms of moderate hypermagnesemia (4-12 mg/dL) may include:

-paralysis

-respiratory depression

-coma

-cardiac arrest

Symptoms of severe hypermagnesemia (> 12 mg/dL) may include:

-prolonged PR interval

-widened QRS

-heart block

What are the ECG findings in hypermagnesmia?

-Mg containing antacids/laxatives

-overuse of mg sulfate

-renal impairment

What are the most common causes of hypermagnesmia?

calcium gluconate

In severe hypermagnesemia, cardiac conduction may be stabilized with intravenous __________.

hemodialysis

Definitive removal of magnesium in patients with renal dysfunction requires __________.