electrolytes, fluid, acid/base

Question 1

1. What are three main players involved in electrolyte balance?

Answer 1

1. GI, renal, endocrine

Question 2

1. water is what % body weight?

ECF?

ICF?

2. intracellular determined by what?

extracellular?

Answer 2

1. 60% (75% if neonate)

20% ECF

40% ICF

2. K

Na

Question 3

1. What is -volemia?
2. what is effective circulating volume?

what is normal?

What is abnormal?

Answer 3

1. changes in blood vol
2. perfusion status of patient (fluid relative to capacity in vascular space)

dec perfusion is counteracted by CV adaptation, conservation of fluid/electrolytes

^vasc space (shock) or compromised compensation

Question 4

How Does each of the following affect fluid and electrolyte balance (and how)?

1. ADH
2. Renin-angiotensin system
3. aldosterone
4. natriuretic peptides

Answer 4

1. fluid retention (induce thirst, ^resorption from tubules)
2. fluid retention (angiotensin II ^renal retention of Na)
3. fluid retention (^Na resorption in exchange for K and H+)
4. fluid loss (antagonize RAS, aldosterone)

Question 5

(Dehydration)

1. Example of hypotonic fluid loss?
2. isotonic fluid loss?
3. hypertonic fluid loss?

Answer 5

1. panting, restricted water access

(protein and PCV also increase)

2. hemorrhage

(TP and PCV variable depending on losses)

3. heavy sweating in horses, some kinds of renal dz/diarrhea

Question 6

(Assessment of Dehydration)

1. usually done by physical exam
2. What lab abnormalities? (remember they have LACK OF PREDICTIBILITY)

Answer 6

2. pre-renal azotemia

^serum protein IF no protein loss

^PCV if no loss/dec prod of RBC

electrolyte changes variable depending on intake (K+ NOT Na/Cl)

Question 7

(Increased Total Body Water)

1. what is most common cause?

Answer 7

1. iatrogenic
   (physiologic: pregnancy, neonatal)
   (pathologic: heart failure, oliguric/anuric renal failure)

Question 8

(Sodium)

1. What promotes sodium retention?
2. what promotes excretion?

Answer 8

1. angiotensin/aldosterone
2. natriuretic peptides

Question 9

(Hyponatremia)

never get from diet

1-3. what three ways?

plus examples of each

Answer 9

1. loss of greater amounts of Na than water

diarrhea, renal dz, sweating, diuretics

2. loss of equal amounts and replacement of water

exudative skin lesions, third space loss, GI fluid loss (diarrhea), hemorrhage

3. dilution

osmotic forces (hyperglycemia), pathologic gain (oliguric/anuric), pregnancy/neonatal

Question 10

(Hypernatremia)

1. how common is increased intake?

2-3. What are the two causes then?

Answer 10

1. rare
2. decreased water intake

adipsia, critical care, lack of access (absence of thirst is rare)

3. excess loss of water

some diarrhea, panting, renal

Question 11

(Chloride)

1. Large amount in GI fluid, sweat (saliva in LA)
2. usually change with Na, but can become independent how?
3. analytical cross reactivity with what?

Answer 11

2. if acid/base abnormalities
3. bromide

Question 12

(Hypochloremia)

1. parallel to sodium
2. sequestration/loss of GI fuid

(acid base abnormalities)

3. varies how with bicarbonate?

If not what does this mean?

Answer 12

3. inversely

that there is a complex/mixed acid/base problem w/ concurrent metabolic acidosis and alkalosis

Question 13

(Hyperchloremia)

1. parallel to what?
2. will see with acidosis or alkalosis?
3. interefering substances like what?

Answer 13

2. acidosis (inverse to bicard)
3. KBr

Question 14

(Potassium)

1-2 serum K managed by what 2 mechanisms?

Answer 14

1. interchange btwn intra/extra (traded for H, cell damage/death)
2. intake via diet vs renal/GI excretion

(losses as for other analytes but renal emphasis)

Question 15

(Hypokalemia)

1-3. What three things cause?

Answer 15

1. decreased intake (anorexia, only cause with ^losses)
2. increased losses (GI, renal, 3rd space, cutaneous)
3. intracellular shift (alkalosis, insulin, glucose)

Question 16

(Hyperkalemia)

1-3. What three things cause?

Answer 16

1. iatrogenic excess
2. failure of elimination/renal retention

(hypoadrenocorticism, oliguria/anuria)

3. extracelluar shift

(hemolysis in LA, massive musc necrosis, metabolic acidosis, insulin def/resistance)

Question 17

(Electrolyte Patterns)

Give possible causes for each

1. all electoryltes increased
2. all electrolytes decreased
3. low sodium and chloride, high potassium

Answer 17

1. free water loss, oversupplementation (calves)
2. loss of high electrolyte content fluid, loss of isotonic fluid with water replacement
3. hypoadrenocorticism, uroabdomen/oliguric-anuric renal failure

Question 18

(Bicarbonate)

increased = alkalemia

1. due to what?

Answer 18

1. loss of acid, often GI or renal

failure to eliminate base

Question 19

(Bicarbonate)

decreased = acidemia

(with high anion gap)

1. due to what?

(with normal anion gap)

2. due to what?

Answer 19

1. excessive acid generated ketones, lactic acidosis
   toxicity: salycyclic acids, ethylene glycol

decreased renal clearance - uremic acidosis

2. increased bicarbonate losses (GI, renal)

Question 20

(anion gap)

1. anion gap = ?
2. AG is what?

Answer 20

1. (Sodium + potassium) - (chloride + bicarbonate)
2. difference between major MEASURED cation and anions = approximation of unmeasured anions

(unmeasured = mostly negatively charged plasma proteins)

Question 21

(Decreased Anion Gap)

1-2. due to what?

Answer 21

1. low albumin
2. increased cationic proteins from gammopathies (rare)

Question 22

(Increased Anion Gap)

1. due to what?

Answer 22

1. increase in unmeasured anions

(lactic acidosis in exercising horses, grain overload, shock, diabetic ketoacidosis, uremic acidosis, intoxication - ethylene glycol)

Question 23

(Chloride Revisited)

1. Usually changes how with what?
2. When Cl- changes disproportionall to sodium, evaluate what?
3. ^bicarb and dec Cl =
4. what if bicarb and Cl change in same direction?

Answer 23

1. Na
2. acid base status
3. alkalosis (opp = acidosis)
4. mixed acid base disorder (arterial blood gas needed for full characterization) but if disorder is metabolic you can fix by correcting the underlying cause