Electrolytes Gone Wild

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Electrolytes Gone Wild
Anthony Dota III PGY 3
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Outline

• Hyponatremia
• Hypernatremia
• Hypokalemia
• Hyperkalemia

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Hyponatremia

• Most common electrolyte disturbance in
  hospitalized patients
• Sodium less than 135 meq/liter
• Can be asymptomatic or manifest as confusion,
  seizures, coma, depends mostly on rate of change
• Treatment based on specific etiology

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Hyponatremia

• First Step
• Determine Plasma
  Osmolality
• Hypotonic Isotonic
  Hypertonic
• Normal Plasma Osmolality 275 290 mosmol/kg

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Hypertonic Hyponatremia

• Hypertonic Hyponatremia- osmolality gt 290
• Excess of an alternate effective osmole, causes
  include
• administration of maltose containing solutions
  common in IVIG infusion
• hypertonic mannitol infusion as used to treat
  increased ICP
• hyperglycemia

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Hypertonic Hyponatremia
119
105
20
850
4.2
15
1.0

• Hypertonic hyponatremia
• 2.4 meq/L increase in sodium for every 100 mg/dL
  above normal for glucose (7.5 x 2.4 18)
• Often times, with correction the sodium will be
  within the normal reference range, so here treat
  the hyperglycemia

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Isotonic Hyponatremia

• Pseudohyponatremia
• hyperlipidemia/hyperproteinemia
• Addition of a non-sodium containing isoosmotic
  solution
• intravesicular exposure to glycine/sorbitol
  common during CBI for urologic procedures

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Hypotonic Hyponatremia

• Plasma osmolality lt 275, most common
• First Step
• Determine Volume
  Status
• Hypovolemic Euvolemic
  Hypervolemic

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Hypotonic Hyponatremia

• Hypovolemic
• Renal losses (diuretics, adrenal insufficiency)
• Extra-renal (diarrhea, inadequate po, insensible
  loss)

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Hypotonic Hyponatremia

• Euvolemic
• SIADH (most commonly)
• Adrenal insufficiency
• Hypothyroidism
• Psychogenic polydipsia
• Low solute intake (beer, or tea toast)

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Hypotonic Hyponatremia

• Hypervolemic
• Congestive heart failure
• Liver cirrhosis
• Nephrotic syndrome
• Advanced renal failure

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Hypotonic Hyponatremia

• Treatment
• Hypervolemic- fluid restriction, /- diuresis
• Euvolemic- free water restriction
• if due to SIADH, and patient is euvolemic, will
  worsen with normal saline, if due to SIADH use
  ADH antagonists, free water restriction, and
  treat underlying cause (i.e. cessation of
  iatrogenic etiology such as SSRIs)
• Hypovolemic- treat with normal saline

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• Hypertonic should only be administered in the
  ICU setting with the aid of a fellow, and for CNS
  symptomatology
• In CNS affected patients you may correct the
  sodium at a more rapid rate of 1.5 2.0 meq/L/hr
  until symptoms resolve
• In non-CNS affected patients, correct at no more
  than 0.5 meq/L/hr with frequent metabolic panels

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So in a situation when saline is indicated, what
concentration do I use and how fast should I
administer it?????
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• CASE
• 75 year old gentleman with a history of
  esophageal carcinoma receiving radiation therapy
  presents to the emergency department with
  dysphagia for 1 month, and more recently
  diarrhea. He has been unable to tolerate solid
  food for nearly a week and has been taking only
  sips of water to ease his throat pain. Initial
  laboratories demonstrate a sodium of 115 meq/L,
  and he does complain of some generalized malaise,
  and some muscle cramps.

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• Physical Examination
• T-97, RR-12, HR-115, BP-105/75, SaO2-97 on room
  air
• Orthostatics
• Dry mucous membranes
• Decreased skin turgor

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• Send serum osmolality, guaranteed to be low
• Hypotonic, hypovolemic, hyponatremia
• Normal saline (Keep time frame in mind )
• 135 meq - 115 meq 20
  meq

1 L
1 L
1 L
40 hours
20 meq Volume of container Liters (TBW)
840 meq
1 L
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• 840 meq / Na 1 Liter / NS
  5.5 Liters / NS

154 meq / Na

• 5,500 ml / NS 136 ml / NS

40 hours
hour
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Hypernatremia

• Most often from a free water deficit secondary
  to secretory and osmotic diarrheas, osmotic
  diuresis, no access to free water, central thirst
  mechanism problems
• Diabetes insipidus, unique, lack of ADH or no
  response
• CASE Patient with sodium of 155 meq/L

155 meq TBW (70 0.6) 6510
meq/Na
1 L
20
6510 meq/Na 145 meq/Na
44.89 liters
X Liters
1 Liter
44.89 Liters - 42 Liters 2890 ml
(free water deficit)
42 Liters
44.89 Liters
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• Now we know the free water deficit, how fast to
  correct it???
• Same as hyponatremia, no more than 0.5
  meq/Liter/hour, or cerebral edema may ensue
• So using this formula, our patient had a 10
  meq/L gap to reach a normal sodium concentration

10 meq 1 L hr 20 hours
1 L
0.5 meq
2,890 ml 145 ml/hour (of free
water)
20 hours
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Hypernatremia

• To be exact regarding this calculation as in ICU
  settings, must adjust for daily insensible free
  water loss
• Typically 30 40 ml of free water per day, add
  these to your fluids
• With urine output in ICU, estimate osmolality by
  Na K

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Hypernatremia

• Diabetes Insipidus
• Central need to give ADH (vasopressin)
• Nephrogenic partial or complete
• unlimited access to free water
• low salt diet
• paradoxically thiazide diuretics

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Hypokalemia

• Normal range 3.5 5.0 meq/L
• Caused by diuresis, Conns syndrome, alkalosis,
  high insulin doses, diarrhea, type I RTA
• Decreased reflexes, rhabdo
• ECG findings
• Repletion, check Mag

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Hyperkalemia

• Causes acidosis, ace-inhibitors, sparing
  diuretics, potassium supplementation, renal
  failure, hypoaldosteronism, tumor lysis
• Case
• Nurse on LK 65 calls you regarding a patient you
  are cross-covering on from the sister team. The
  evening renal function panel that was drawn
  showed K is 6.5 . What would you like to do?????
  

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Hyperkalemia

• Treatment
• Calcium
• Insulin
• D50
• Kayexelate

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Hyperkalemia

• other ECG changes
• K gt 7
• Acute renal failure, crush injuries, altered
  mentation

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END