Electrolyte Disturbances Flashcards

1
Q

Potassium

  • where in cell
  • importance
  • how excreted
A
  • mostly intracellular
  • ratio intra/extracellular essential for cell membrane potential
  • mostly excreted by kidneys
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2
Q

Hyperkalemia

- value

A
  • Greater than 5.1/5.5 mEq/L
  • > 7 can lead to hemodynamic and neuro consequences
  • > 8.5 can lead to respiratory paralysis or cardiac arrest, can be fatal
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3
Q

Hyperkalemia

- causes

A
  • Lab/human error (if break RBC can leak K+ out)
  • Renal failure and acidosis (Cell will bring excess H+ into cell, push K+ out. Total body K+ has not changed but shift has occurred)
  • Cell death (burn, tumor lysis syndrome)
  • Drugs, toxins, medications
    • K+ supplements
    • Non-selective BB (propranolol)
    • Succinylcholine (paralytic used in Em medicine)
    • Digoxin
    • K-sparing diuretics (spironolactone)
    • ACEi
    • Pentamidine and trimethoprim
    • ACEi and trimethoprim were most common drug causes in recent study
    • Reduced kidney function was common cause in recent study
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4
Q

Hyperkalemia

- EKG findings

A
  • Peaked T wave
  • Widened QRS
  • Loss of P wave
  • Sine wave
  • V-fib/asystole
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5
Q

Hyperkalemia

- Treatment

A
  • Treat once confirmed not a lab error, true hyperkalemia and >6.5 or EKG changes
  • Figure out the CAUSE don’t just treat the imbalance
    Then
    1. Membrane antagonism
    2. Intracellular shift of K+
    3. Eliminate K+ from body
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6
Q

Hyperkalemia

- Membrane antagonism (tx)

A

• Calcium, stabilizes heart
• Dr. Hunt uses when Hyperkalemic and EKG changes
• Options
- Calcium chloride (3X ca content as ca gluconate, give through central line)
- Calcium gluconate (better if only have peripheral line but less bang for buck)

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7
Q

Hyperkalemia

- intracellular shift of K (tx)

A
  • IV insulin (co-transporter forces K back into cells)
  • Albuterol/Salbutamol
  • IV sodium bicarb (only if in acidosis)
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8
Q

Hyperkalemia

- Eliminate K from the body (tx)

A
  • Kayexalate (binds in bowel, comes out in stool). Risk of colonic necrosis
  • Furosemide (risk of hypokalemia). Dr. Hunts first option, let nephrologist order kayexalate
  • Dialysis: if reduced kidney function, not a rapid solution
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9
Q

Hyperkalemia

- mnemonic

A
C BIG K Di
• Calcium
• Bicarb, beta agonist
• Insulin
• Glucose
• Kayexelate, Lasix
• Dialysis
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10
Q

Pseudohyperkalemia

A
  • D/t collection and storage of specimen
  • Pt clenched fist when sample was taken, difficulty collecting sample
  • Cooling of sample or deterioration dt length of storage
  • Thrombocytosis
  • Severe leukocytosis can cause psuedohypokalemia
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11
Q

Hypokalemia

- value

A

Serum K+ <3.5 mEq/L, severe is <2.5

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12
Q

Hypokalemia

- first steps

A
  • Assess muscle weakness, increased respiratory muscle use
  • EKG changes? Medical emergency
  • ABG usually helpful
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13
Q

Hypokalemia

- causes

A

**Think diuretics and diarrhea
- Drugs (thiazides, furosemide), Toluene in huffers
- GI loss (v/d)
- Hormones (high aldosterone or cortisol)
- Bicarb: metabolic alkalosis (H+ out of cell, K+ in)
- Renal tubular defects
- Mg deficiency
- Decreased intake
- Increased loss
• Renal (CHF, nephrotic syndrome, dehydration)
• Renal tubular defects
• GI losses (v/d/laxatives)
• Drugs (diuretics, ampho B, mannitol, aminoglycosides)
- Transcellular shifts
• Alkalosis (vomiting, diuretics)
• Insulin
• Beta agonists

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14
Q

Hypokalemia

- clinical presentation

A
  • CV: arrhythmia, EKG change
  • Skeletal muscle: weakness (MC presentation in ER), cramps, tetany, paralysis (K<2)
  • Smooth muscle: constipation, urinary retention
  • Metabolic alkalosis
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15
Q

Hypokalemia

- EKG changes

A
  • PR prolongation
  • T wave flatten/inversion
  • ST depression
  • U waves
  • Long QT interval (T&U fuse together)
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16
Q

Hypokalemia

- Tx

A
  • PO replacement preferred
  • IV also an option
  • Goals: K between 4 and 4.5 mEq/L
  • Might have to increase Mg too (>1.0)
  • 1 mEq drop in serum level = 100-200 mEq loss in total body store
  • Options
    KCL PO, KCL IV, K-phos, K-bicarb, K-citrate
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17
Q

Hypokalemia

- when is IV indicated

A
  • Dysrhythmias
  • Prominent sx
  • Unable to tolerate PO
  • Likely if K<2.5
  • Give slowly, preferably via central line
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18
Q

Sodium

  • where in body
  • how does it move around
  • two major hormones related to Na levels
A
  • Extracellular cation, closely related to total body water
  • Moves into cells depending on osmolality
  • Moved out of cell by Na/K ATPase
  • Renin: released with low intravascular volume: triggers Na reabsorption and K secretion in distal nephron via aldosterone
  • ADH: released when there is high serum osmolality. Enhances renal water reabsorption. Also triggered by angiotensin, catecholamines, opiates, caffeine, stress, hypoglycemia, hypoxia
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19
Q

Hyponatremia

- serum level

A

<135 mmol/L

  • Must ensure true hyponatremia by adjusting for glucose
  • For every 100 above 100 glucose, add 1.6 mmol sodium
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20
Q

Hyponatremia

- first steps

A

Quickly eval:

  • neuro symptoms
  • what is the pt’s volume status
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21
Q

Hyponatremia

- Three types

A
  1. hypervolemic
  2. Euvolemic
  3. Hypovolemic
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22
Q

Hyponatremia

- hypervolemic

A
  • Decreased effective circulating volume, fluid elsewhere (edema): CHF, hepatic cirrhosis, nephrotic syndrome
  • ADH is stimulated = water retention
  • CHF, cirrhosis, nephrotic syndrome
  • Pt will look “wet”
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23
Q

Hyponatremia

- euvolemic

A

• Inappropriate ADH (SIADH, etc.)
- SIADH, psychogenic polydipsia, beer potomania, adrenal insufficiency, MDMA, hypothyroid
- SIADH causes: tumor, infection, trauma, pulm dz, drugs (diuretics and chemo)
• Pt not wet or dry

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24
Q

Hyponatremia

- hypovolemic

A
  • ADH secretion stimulated by volume depletion: Renal loss, GI loss, excessive sweating, 3rd spacing
  • Pt will look dry
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25
Hyponatremia | - clinical presentation
* when <125 mmol/L ``` • Lethargy, confusion, agitation • n/v • weakness • focal neuro deficits • Seizures (increased risk when <120) • Altered LOC *pts with chronic hyponatremia may tolerate lower levsl without sx than acute onset ```
26
Hyponatremia | - workup
``` • CBC • Electrolytes • Serum osmolality • Uric acid • TSH/cortisol? Urine: UA, urine electrolytes, osmolality, creatinine ```
27
Hyponatremia | - Tx overview
* treat the neuro changes and then quickly do nothing
28
Hyponatremia | - Treatment rule
Rule of 6s: - Increase Na by 6 mEq per day - Increase Na by 6 mEq in 6 hours if neuro sx
29
Hyponatremia | - tx if neuro sx
- IV 100 cc hot salt (3% saline) over 20 min - Repeat if no improvement. - Then stop, fluid restrict, admit to hospital - If neuro persists, consider CT head
30
Hyponatremia | - Risk of overcorrect
If overcorrect, risk osmotic demyelination syndrome (>10 mEq/L in 24 hour period) • RF: chronic hyponatremia, serum na <105, alcoholism, malnutrition/liver dz • Correct with DDAVP and nephrology consult
31
Hyponatremia | - Tx if no neuro
* Volume resuscitation, saline lock IV, NPO, foley to monitor output * Replace K will raise serum Na
32
Hypernatremia | - serum level
>145 mEq/L | State of hyperosmolality
33
Hypernatremia | - general causes
- thirst/water access related - renal concentrating problem (kidney or hormone) - free water loss
34
Hypernatremia | - MC etiology
debilitated pts who depend on others for hydration, often long care facilities
35
Hypernatremia | - Other etiologies
- Reduced water intake • Inability to obtain water or disorders of thirst perception - Increased water loss • GI: v/d third spacing • Renal: diabetes insipidus, renal tubular defects. Diabetes insipidus: loss of large amts of dilute urine, lack concentrating ability in distal nephron. Central: lack ADH secretion, nephrogenic: kidneys don’t respond to ADH • Dermal: sweating, severe burns - Increased sodium • Exogenous sodium: salt tablets, hypertonic saline • Increased reabsorption: Cushings, exogenous corticosteroids, congenital adrenal hyperplasia
36
Hypernatremia | - work up
- CBC - serum electrolytes - serum glucose - BUN/Cr - urine electrolytes - urine osmolalility - plasma osmolality - urine output quantity
37
Hypernatremia | - clinical presentation
- Dehydration - Anorexia, nausea, vomiting, fatigue - Lethargy, confusion, coma - Hyperreflexia, spasticity, tremor, ataxia - Upgoing toes, hemiparesis
38
Hypernatremia | - serum osmolality levels and associated sx
* >350: excessive thirst * >375 weakness and lethargy * >400 ataxia, tremor * >420 focal neuro deficits, hyperreflexia * >430 coma and seizure
39
Hypernatremia | - Dx
- Volume status - Hypovolemia: • Urine <10 mEq/L: extrarenal fluid loss • Urine >20 mEq/L: renal losses - Euvolemia: • High urine osmolality: increased insensible losses • Low urine osmolality: diabetes insipidus
40
Hypernatremia | - Treatment depends on what
timing of onset - acute (fast onset, <48 hours) = fast treatment - chronic (slow onset, >48 hours) = slower treatment
41
Hypernatremia | - Treatment rates for acute and chronic
- Acute: correct at 1 mmol/L per hr | - Chronic: correct at 0.5 mmol/L per hour, no more than 10 mmol/L per 24 hrs
42
Hypernatremia | - Treatment
- Correct Na - Replace 50% of free water deficit in first 12-24 hours, remaining over next 24 hours. - Serial serum and urine electrolytes - Serial neuro exams
43
Hypernatremia | - complications
* Coma and seizure * Cerebral edema if rapid correction * Intracerebral hemorrhage, esp in neonates
44
Hypocalcemia | - value
< 8.5 mg/dL
45
Hypocalcemia | - causes
- Hypoparathyroidism (iatrogenic) - Vitamin D deficiency - Hyperphosphatemia (binds calcium) - Precipitation of calcium - Chelation of calcium
46
Hypocalcemia | - what lab needs to be drawn for accurate measure
ionized calcium
47
Hypocalcemia | - what two states can falsely depress ca measurements
- alkalosis | - hypoproteinemic states
48
Hypocalcemia | - how to correct calcium lab value
0.8 mg/dL calcium decrease for every 1 g/dL reduction in albumin
49
Hypocalcemia | - Presentation
- Tetany ** - Paresthesia in circumoral region and extremities - Laryngospasm, bronchospasm (severe) - Abd cramps, urinary frequency - Hypotension and arrhythmia - Chvostek’s sign (tap facial nerve = twitch) - Trousseau’s sign (blow up bp cuff = hand spasm) - EKG: prolonged QT interval
50
Hypocalcemia | - Treatment
- Symptomatic: 10 ml of 10% IV calcium gluconate over 10 minutes • Do not give with bicarbonate or phosphate containing solution - Take serial ca measurements - Correct alkalosis if present - Long term ca supplement
51
Hypercalcemia | - value
>10.5 mg/dL
52
Hypercalcemia | - causes
- Hyperparathyroidism * - Malignancy* - Also: Pagets dz, excessive vitamin D intake, granulomatous disorders, milk alkali syndrome, drugs (thiazides, lithium)
53
Hypercalcemia | - clinical features
- Anorexia, n/v - Irritability, confusion - Weakness, ataxia, lethargy - Polyuria - EKG: Peaked T waves, Shortened QT interval
54
Hypercalcemia | - Tx
- Hydration with normal saline - Loop diuretics (furosemide) - Hemodialysis - Want urine output >3 L day - Supplement with K and Mg - Severe: bisphosphonates
55
Hypomagnesemia | - lab value
mg <1.7 mEq/L
56
Hypomagnesemia | - how to order
Have to order separate, not on standard CMP
57
Hypomagnesemia | - causes
- Inadequate intake - Reduced GI absorption - Renal losses: diuresis, hyperparathyroidism - Drugs: theophylline, diuretics, ethyl alcohol, aminoglycoside, amph. B - Can occur in DKA with decreased K
58
Hypomagnesemia | - clinical features
- Asx - Associated with hypocalcemia and hypokalemia - Anorexia, weakness, paresthesia - Confusion, seizure, coma - A fib, potentiates digitalis toxicity - EKG: Prolonged PR and QT intervals
59
Hypomagnesemia | - Treatment
- Asx: 2 g oral mg sulfate - Sx: mg sulfat 1-2 g IV 10 minutes - Monitor: tendon reflexes, resp rate, urine output
60
Hypermagnesemia | - lab value
mg >2.5 mEq/L
61
Hypermagnesemia | - causes
- Antacids or laxatives - Iatrogenic: mg citrate, antacids - Hypothyroidism - Adrenal insufficiency Lithium
62
Hypermagnesemia | - Clinical features
- Hyporeflexia, drowsy, skeletal muscle weakness - Hypotension - Prolonged PR interval and widening of QRS complex - Respiratory arrest
63
Hypermagnesemia | - Treatment
- 10 ml of 10% calcium gluconate IV over time 10 (stabilize cardiac membrane) - Loop diuretic with ½ normal saline in 5% dextrose: excrete it - Peritoneal/hemodialysis