Electrolytes Flashcards

1
Q

What are the major ECF ions

A

Na and Cl

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2
Q

What are the major ICF ion

A

K

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3
Q

how is Hco3 generated

A

Carbonic anhydrase reactions in the lungs, gastric mucosa, kidney and RBC

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4
Q

TCO2

A

Total extractable CO2 from serum or plasma by addition of an acid. Most of it (955) bicarb. and HCO2 and TCO2 are essentially equal

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5
Q

What can cause abnormal electrolyte concentrations in plasma or serum

A
  1. Increased or decreased intake
  2. Shift between ECF and ICF
  3. Increased renal retention
  4. Increased loss through GI, renal, skin, airway
    Hydration is essential to assessment
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6
Q

Mechanisms of dehydration and Na changes

A
  1. Loss or sequestration of hypotonic fluid (hypertonic dehydration)
  2. Loss of isotonic fluid (isotonic dehydration)
  3. Loss of hypertonic fluids (hypotonic dehydration)
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7
Q

Hypertonic dehydration

A

-Pure water loss results in hypernatremia
-ICF and ECF share burden but ECF has greater osmolality so water shifts to ECF

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8
Q

Causes of hypertonic dehydration

A

No access to water with continued insensible loss
(Panting, hyperventilation, fever)

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9
Q

Isotonic dehydration

A

-Fluids lost have the same amount of electrolytes as blood or serum
-Normonatremia
-ICF osmolality=ECF
-Animal shows other signs of dehydration (skin turgor, hyperalbuminemia, relative erthrocytosis)

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10
Q

Causes of isotonic dehydration

A

Vomiting and Diarrhea

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11
Q

Hypotonic dehydration

A

-Fluids with more electrolytes lost compared with blood/serum
-ECF osmolality < ICF fluid shifts into ICF

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12
Q

Hypotonic dehydration causes

A

Secretory diarrhea

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13
Q

Tonicity

A

Effective osmolality of a solution
Effective osmole-> do not cross permeable membranes
Ineffective osmoles-> readily cross membranes

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14
Q

Measured osmolality

A

Uses freezing point (lower if the concentration is raised) and measures effective and ineffective osmoles

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15
Q

Calculated osmolality

A

2(Na + K) if glucose and UN normal
Typically 300-310 and 10mOsm less than the measured

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16
Q

Osmolar gap

A

Measured osm- calculated osm
Normally 10mOsm

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17
Q

Increased osmolal gap

A

Increased number of osmotically active particles in blood not accounted for in equation (Lactate, ketones, alcohols, ethylene glycol, mannitol, oxalic acid, salicylic acid)

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18
Q

What is the mahor determinant of extracelullar tonicity

A

Na

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19
Q

Plasma Na controlled by

A
  1. Regulation of blood volume
  2. Regulation of plasma osmolality/ tonicity
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20
Q

Serum Na is dependent on what

A

Ratio of total body Na/tbH2O
Hypernatremia means that increase in Na means tbH2O is normal or there is normal Na but decreased tbH2O or decrease in Na leads to severe decrease in tbH2)

21
Q

Mechanisms of hypernatremia

A

-Decreased H2O intake
-Pure H2O loss
-H2O loss> Na loss
-Excess Na intake
-Decreased Na excretion

22
Q

Hyponatremia mechanisms

A

-Na loss> H2O loss
-Renal Na wasting
-H2O retention> Na retention (with or without edema)
-Osmotic shifting of H2O to ECF
-Shift of Na down concentration gradient from intravascular to extravascular

23
Q

Normonatremia

A

Does not necessarily mean normal tbNa
-Hypervolemic
-Hypovolemic/dehydration

24
Q

Serum K is dependent on

A
  1. Shifting of K in and out of cells
  2. TbK (from intake and excretion)
    If acid base is normal-> K reflects tbK
    If not normal A/B-> abnormal tbK
25
Alkalosis and K
Increased bicarb-> hypokalemia
26
Inorganic Acidosis and K
Decrease bicarb-> hyperkalemia
27
Organic acidosis and K
No hyperkalemia because as H enters the cell it is travelling with its anion (lactate) and maintains electroneutrality
28
Excess K loss and acid base
Leads to alkalosis because K enters the plasma from the cell and H enters the cell
29
Mechanisms of hyperkalemia
-Shift in exchange for H -Cellular necrosis -Pseudohyperkalemia -Insulin deficiency -Decreased renal excretion of K -Increased intake
30
Pseudohyperkalemia
Marked thrombocytosis and take a serum sample which clots and releases K from platelets and if they have a lot of platelets have a lot of K. to determine but it in a heparinized tube (green top)
31
Mechanisms of hypokalemia
-ECF-> ICF shift in exchange for H -Insulin administration -Decreased K intake -Increased K excretion -Increased alimentary K loss
32
Sodium: Potassium ratio
If it Na decreased , K may be ok If K is increased , Na may be ok If Na is decreased, K may be increased
33
Hypoadrenocorticism and Na: K ration
Increased Na loss and increased K retention <15
34
Control of Cl
1. Renal resorption and excretion 2. Alimentary tract functions
35
Shifts in Cl
Maintain electroneutrality -Usually follows Na -Inverse to HCO3
36
Interpreting Hyperchloremia
-Concurrent hypernatremia-> same cause -Normonatremia-> due to decreased HCO3 -Hyperchloremic metabolic acidosis-> Loss of NaHCO3 fluid (diarrhea)
37
Interpreting hypochloremia
-Concurrent hyponatremia-> same cause -Normonatremia-> due to increased HCO3 and loss of HCl -Normonatremia-> decreased HCO3-> must have unmeasured anions present (metabolic acidosis)
38
Alimentary tract causes of hypochloremia
HCl is not being recycles but still get bicarb is being made. Cl has to leave ECF due to the bicarb and you get Cl loss. Causes metabolic alkalosis
39
Renal mechanisms for hypochloremia
Occurs with metabolic acidosis. Look at chart
40
If Na and Cl change in same direction
THink hydration problems
41
If Na and Cl change in opposite directions
Think acid/base abnormalities
42
Metabolic alkalosis
Increase in HCO3, usually due to loss of H or compensation for chronic respiratory acidosis
43
Metabolic acidosis
Decrease of HCO3, usually due to generation of excess H or loss of HCO3. May see with compensation for chronic respiratory alkalosis
44
Mechanisms for increased HCO3
-Gastric loss of H -Renal loss of H -Shift from ECF to ICF in exchange for K (Hypokalemia)
45
Mechanisms for decreased HCO3
-Increased H from metabolic process and HCO3 gets used up -Decreased renal H clearance and HCO3 used up -Alimentary losses -Renal loss
46
Lactate production
Product of anaerobic glycolysis during hypoxia in skeletal muscles and can then be used for glyconeogenesis
47
Types of hyperlactatemia
1. Hypoxia 2. Metabolic: grain overload
48
Metabolic hyperlactemia
Grain overload leads to increase formation of L lactate and (D lactate by bacteria) increases lactate absorption by ruminal mucosa and increases plasma lactate