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IM_Renal and GU > Magnesium and Potassium > Flashcards

Magnesium and Potassium Flashcards

1
Q

normal Mg level

A

1.8-2.5

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2
Q

Where is 2/3rds of magnesium located in the body?

A

BONES

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3
Q

What is the major regulator of Mg in the body?

A

kidneys

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4
Q

What are some GI causes of hypomag?

A
  • malabsorption, steatorrhea (MCC)
  • fistulas
  • nonadequate intake (bad TPN, prolonged fasting)
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5
Q

What kind of subtstance abuse is a common cause of hypomag?

A

ALCOHOLISM

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6
Q

What renal causes of hypomag?

A
  • SIADH
  • diuretics
  • Bartter syndrome
  • drugs: gentamicin, amphotericin B, CISPLATIN!!!
  • renal transplant
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7
Q

Symptoms of hypomag

A
  1. marked neuromuscular and CNS HYPERirritability (twitching, weakness, tremors, hyperreflexia, seizures, AMS)
  2. hypocalcemia (due to decreased release of PTH when Mg is low)
  3. hypokalemia (Mg and K follow each other)
  4. ECG changes (prolonged QT, T-wave flattening, torsades eventually :(
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8
Q

Treatment hypomag?

A

mild - oral (Mg oxide)

severe - parenteral (Mg sulfate)

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9
Q

Causes of HYPERmag

A
  1. renal failure (MCC)
  2. burns/trauma/surgical stress
  3. excessive intake (laxatives/antacids/Mg sulfate during pre-eclampsia) while kidney isn’t working as well
  4. rhabdomyolisis
  5. adrenal insufficiency
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10
Q

Clinical features of HYPERmag

A
  • progressive loss of DTR (CLASSICALLY FIRST SIGN)
  • nausea, weakness
  • facial paresthesias
  • ECG changes that resemble hyperkalemia (increased PR, QRS widening, peaked T waves, sinusoidal pattern)
  • somnolence -> coma -> death from resp/card arrest
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11
Q

Treatment of hypermag

A
  • withhold any Mg administration
  • IV calcium gluconate
  • saline/furosemide
  • dialysis or intubation if needed
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12
Q

Normal K

A

3.5 - 5.0

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13
Q

Causes of hypokalemia

A
  1. GI losses (vomiting, diarrhea, excessive sweating, malabsorption, laxatives/enemas)
  2. Renal losses (diuretics, Bartter syndrome renal tubular/parenchymal disease, primary/secondary hyperaldosternoism, excessive glucocorticoids)
  3. drugs - Bactrim, amphotericin B, epinephrine (watch out for hypokalemia in trauma patients, since hypokalemia can occur due to increased epinephrine levels)
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14
Q

Clinical features of hypokalemia

A
  1. arrhythmias (prolongs normal cardiac conduction)
  2. muscular weakness, fatigue, paralysis, muscle cramps
  3. decreased DTR
  4. paralytic ileus
  5. polyuria/polydipsia
  6. n/v
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15
Q

You should always monitor K levels when giving a patient what cardiac medication?

A

DIGOXIN!!!!!

esp when giving it for CHF (since these patients are also on diuretics)…potentially could WORSEN the hypokalemia and makes patient more vulnerable to digoxin toxicity

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16
Q

What ECG changes can you see with HYPOkalemia

A

flattened T waves -> inverted, U waves

17
Q

How to work up hypokalemia

A

check K level -> r/o lab error, redistribution (insulin, epi, metabolic alkalosis) -> check urine K -> check ABG

18
Q

hypokalemia, urine K< 20 = extrarenal loss, normal acid base

A
  • decreased K intake
  • laxative abuse
  • excessive sweating
19
Q

hypokalemia, urine K < 20=extrarenal loss, metabolic acidosis

A

GI causes

  • diarrhea
  • fistula
  • villous adenoma
20
Q

hypokalemia, urine K > 20 = renal loss, metabolic acidosis

A

RTA, DKA, acetazolamide, ureterosigmoidostomy

21
Q

hypokalemia, urine K > 20 = renal loss, metabolic alkalosis

A

FIX THE DAMN METABOLIC ALKALOSIS THAT’S WHAT’S MAKING HIM HYPOKALEMIC

remember alkalosis - shifts K into cells
acidosis - pulls K out of cells

22
Q

How to treat hypokalemia

A 
oral KCl (safest method)  or IV KCl (max 10meq/hr in peripheral, 20meq/hr in central line) (when more severe, but this also burns!!)
- administer 10 mEq of KCl to raise K up 0.1 pts

treat underlying disorder, also make sure to correct any coexisting hypomag since Mg and K go together

23
Q

What can cause pseudohyperkalemia

A
  • prolonged use of tourniquet without fist clenching

- hemolyzed sample that wasn’t processed quickly enough

24
Q

Clinical features of hyperkalemia

A
  • arrhythmias
  • muscle weakness, flaccid paralysis (rare)
  • decreased DTR
  • n/v, intestinal colic, diarrhea, resp failure
25
Q

Sequence of ECG changes in hyperkalemia and what value do you see ECG changes become prominent?

A

peaked T waves -> QRS widening -> PR prolongation -> loss of P waves -> sinewave pattern -> Vfib!!!!!

K>6

26
Q

How to treat hyperkalemia

A
  1. protect the heart! (give CALCIUM GLUCONATE to stablilizes myocardium, decreases excitability)…but watch out if giving digoxin (hypercalcemia predisposes patient to digoxin toxicity)
  2. shift K back into cells (INSULIN does this, but also give GLUCOSE to prevent hypoglycemia, also SODIUM BICARB)
  3. remove excess K (kayexalate prevents reabsorption in colon, HD in intractable K or in renal failure, furosemide)
27
Q

How to work up hyperkalemia

A

r/o spurious/pseudohyperkalemia, r/o redistribution, check renal function, check aldosterone

28
Q

What are some conditions/meds that will cause redistribution hyperkalemia

A

metabolic acidosis, insulin deficiency, B blockers, succinylcholine, digitalis overdose

29
Q

hyperkalemia, normal renal function, low aldosterone

A

hyporeninemic hypoaldosteronism, Addison’s disease, ACE inhibitors

30
Q

hyperkalemia, normal renal function, high aldosterone

A 
K sparing diuretics (spirinolactone,amiloride, triamterene)
tubular disorders (sickle cell nephropathy, SLE, amyloidosis)
31
Q

hyperkalemia, decreased renal function

A

TREAT RENAL RAILURE

IM_Renal and GU (10 decks)

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