Hyper-Hypokalemia & Hyper-Hyponatremia (Andelin) Flashcards

1
Q

What is considered hyponatremia?

A

Low serum sodium <135 mEq/L
Mild hyponatremia 130-134 mEq/L
Moderate hyponatremia 120-129 mEq/L
Severe hyponatremia <120 mEq/L

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2
Q

What is considered severe hyponatremia?

A

Severe hyponatremia <120 mEq/L

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3
Q

Symptoms of hyponatremia?

A

Na+ < 125 mEq/L (>125 mEq/L = asymptomatic)
Mostly neurological symptoms: Headache, fatigue/lethargy, Dizziness, nausea, Gait instability, Confusion, Psychosis, Seizures, Coma

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4
Q

Hypovolemic hyponatremic exam findings

A

Hypotension
Tachycardia
Poor capillary refill
Increased skin turgor
Dry oral mucosa or tongue fissuring
Flat JVD
Hx of decreased urine output

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5
Q

Hypervolemic hyponatremic exam findings

A

Hypertension
Sacral or LE edema
JVD
Dilated IVC on ECHO

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6
Q

Cause of Hypovolemic Hyponatremic with Urine Na+ >30 mEq/L

A

Renal fluid loss: Diuretic excess

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7
Q

Causes of Hypovolemic Hyponatremic with Urine Na+ <30 mEq/L

A

Extrarenal fluid loss:
Vomiting
Diarrhea
Third spacing (burns - lots of water loss)

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8
Q

Causes of Euvolemic Hyponatremic with Urine Na+ >30 mEq/L

A

Drugs
SIADH

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9
Q

Causes of Euvolemic Hyponatremic with Urine Na+ <30 mEq/L

A

(Very dilute urine)
Primary polydipsia

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10
Q

Causes of Hypovolemic Hypernatremic with Urine Na+ <30 mEq/L

A

Nephrotic Syndrome
Heart failure
Cirrhosis

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11
Q

Causes of Hypovolemic Hypernatremic with Urine Na+ >30 mEq/L

A

AKI
CKD

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12
Q

Treatment of hyponatremia

A

Give hypertonic saline (3%)
Acute (<48 hrs) rapid correction
Chronic (>48hrs) avoid rapid correction (ODS); increase 8-10 mEq/L per day; no more than 18 in first 48 hrs

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13
Q

Osmotic Demyelination Syndrome (ODS)

A

In the case of a patient with hyponatremia where there is rapid Na+ correction. Demyelination occurs in the pontine (pons) and extrapontine neurons typically 2-6 days later. Symptoms are often irreversible (very serious) can potentially develop locked-in syndrome (awake but unable to move or communicate)

Diagnosed with head MRI about 3-4 weeks later.

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14
Q

SIADH

A

too much ADH
inability to suppress ADH secretion, lots of water retention (aquaporins); urinary Na excretion. Urine will be concentrated (urine osmolality>serum osmolality)

Euvolemic hyponatremia
Urine Na+ > 30 mEq/L

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15
Q

Common causes of SIADH

A

head trauma or CNS disorder
Paraneoplastic syndrome - small cell carcinoma of the lung (most common)
Pneumonia
Carbamazepine

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16
Q

Hyponatremia Summary

A

Common in older adults and hospitalized patients.
Na > 125 mEq/L = asymptomatic
Na < 125 mEq/L = neurological symptoms
Hypovolemic, Euvolemic and Hypervolemic
Workup includes: serum osmolality, urine osmolality and urine sodium
Treatment for acute = rapid correction, chronic = avoid rapid correction b/c ODS risk.

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17
Q

Cirrhosis causes what kind of electrolyte abnormality?

A

Hypervolemic hyponatremia
Serum Na+ <135 mEq/L
Urine Na+ <30

Treat with IV isotonic saline (asymptomatic)
Hypertonic saline (symptomatic)

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18
Q

Excessive diuretics causes what kind of electrolyte abnormality?

A

Hypovolemic hyponatremia
Urine Na+ > 30 mEq/L

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19
Q

Excessive diarrhea/vomiting causes what electrolyte abnormality?

A

Hypovolemic hyponatremia
Urine Na+ <30 mEq/L

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20
Q

What is considered hypernatremia?

A

Elevated serum sodium ( >148 mEq/L)
Primarily seen in infants and elderly

21
Q

Symptoms of hypernatremia?

A

Primarily neurological symptoms:
Irritability
Altered mental statusLethargy
Ataxia
Hyperrelexia
Intracranial hemorrhages

22
Q

Pathogenesis of hypernatremia

A

Defect in urine concentrating capacity (ADH prob-suppressed or not responsive) coupled with inadequate water intake.

  1. unreplaced water loss
  2. sodium overload
23
Q

What is the risk of rapid correction in hyponatremia treatment?

A

Osmotic Demyelination Syndrome (ODS)

24
Q

What is the risk of rapid correction in hypernatemia treatment?

A

Cerebral edema

25
Q

Treatment of hypernatremia

A

Give hypotonic saline or 5% Dextrose in water (D5W)
Acute (<48 hrs) rapid correction
Chronic (>48hrs) avoid rapid correction (cerebral edema); lower 10-12 mEq/L per day; no more than this

26
Q

Hypernatremia Summary

A

Common in infants and elderly.
There are mainly neurological symptoms.
Na > 148 mEq/L
Workup includes: BMP or CMP
Treatment for acute = rapid correction, chronic = avoid rapid correction b/c cerebral edema risk.

27
Q

What is considered hyperkalemia?

A

Elevated serum potassium (> 5.0 or 5.5 mEq/L)

28
Q

Symptoms of hyperkalemia?

A

Depends on severity of hyperkalemia (can be asymptomatic, mild, or life threatening)
Can cause cardiac arrhythmias (V fib), skeletal muscle weakness, or metabolic acidosis

29
Q

ECG changes in hyperkalemia

A

6-7 mEq/L = peaked t waves
> 9 mEq/L = extremely severe hyperkalemia - V fib

30
Q

What are some common causes of hyperkalemia due to transcellular shift?

A

metabolic acidosis
insulin deficiency, hyperglycemia, hyperosmolality
increased tissue catabolism (rhabdomyolysis)
Meds: B2 blockers or succinylcholine
Blood transfusions
Exercise

31
Q

What are some common causes of hyperkalemia due to decreased renal excretion?

A

Low aldosterone secretion (ACEis/ARBs)
Aldosterone resistance (spironlactone/trimethoprim)
AKI/CKD
Hypovolemia
Ureterojejunostomy (kidneys attached to bowel)
Intrinsic renal defect (rare)

32
Q

What is the workup for hyperkalemia?

A

BMP or CMP (ALWAYS repeat to rule out lab error)
ECG - look for cardiac abnormalities

33
Q

Hyperkalemia Treatment

A

Ca BIG K
Ca - IV Calcium gluconate (indicated when peaked t waves are present)
B - Inhaled B2 agonist (albuterol) or IV Bicarbonate (less effective)
IG - IV insulin and glucose
K - Oral Kayexalate (gets rid of K+)

34
Q

Treatment of IV Calcium gluconate

A

used in hyperkalemia when peaked t waves are present; stabilizes cardiac membrane

35
Q

Treatment of inhaled B2 agonist

A

albuterol - used in hyperkalemia when caused by changes in transcellular shift

36
Q

Treatment of IV Bicarbonate

A

used in hyperkalemia when caused by changes in transcellular shift (less effective then B2 agonist - albuterol)

37
Q

Treatment of IV insulin and glucose

A

used in hyperkalemia when caused by changes in transcellular shift

38
Q

Treatment of oral Kayexalate

A

used in hyperkalemia to get rid of K+; exchanges Na+ ions for K+ primarily in the colon (cation exchange)

39
Q

Hyperkalemia Summary

A

Common (kidney injury)
K+ > 5.0 or 5.5 mEq/L
Cardiac arrhythmias/ Muscle weakness
Workup includes: BMP or CMP (REPEAT) and ECG
Treatment: Ca BIG K

40
Q

What is considered hypokalemia

A

low serum potassium (< 3.5 mEq/L)

41
Q

Symptoms of hypokalemia

A

usually not symptomatic until < 3.0 mEq/L
Skeletal muscle weakness (severe cases - diaphragmatic weakness - breathing)
Muscle cramps - potentially rhabdomyolysis
Cardiac arrhythmias
Metabolic alkalosis

42
Q

ECG changed in hypokalemia

A

3.5 = low t wave
3.0 = low t wave; high u wave

43
Q

What are the three main reasons for hypokalemia?

A
  1. Transcellular shift (increased K+ uptake by cells; out of blood)
  2. Extra-renal loss
  3. Renal loss
44
Q

What are the 3 main causes of transcellular shift in hypokalemia?

A
  1. B agonist (abuterol)
  2. Metabolic alkalosis (increase in arterial pH)
  3. Insulin (DKA treament - IV insulin leads to intracellular shift of K+ and thus a decrease in serum K+) and refeeding syndrome
45
Q

What are the main causes of extra-renal loss in hypokalemia?

A

GI loss - Vomiting, NG suctioning, diarrhea
Cutaneous loss - sweating

46
Q

What are the main causes of renal loss in hypokalemia?

A

Diuretics (thiazides and loop diuretics)
Increased mineralcorticoid activity (hyperaldosteronism)
Hypomagnesium
RTA Type 1 or 2
Intrinsic renal defect (Bartter, Gitleman, Liddle Syndrome)

47
Q

What is the workup for hypokalemia?

A

BMP or CMP
ECG - look for cardiac abnormalities
Serum magnesium (remember can lead to persistent hypokalemia)

48
Q

Hypokalemia treatment

A

Replace K+ deficit (potassium chloride)
K level will increase by 0.1 mEq/L for every 10 mEq of KCl given
Replace magnesium if low
Repeat K+ to ensure it has normalized

49
Q

Hypokalemia Summary

A

Common (due to GI fluid loss, diuretics, insulin)
K+ < 3.5 mEq/L
Skeletal muscle weakness, cramps, and cardiac arrhythmias
ECG: prominent u waves, flat t waves
BMP/CMP, ECG, magnesium check (refractory hypokalemia) and treat by replacing K+ (KCl) and magnesium if low.