Fluid and Electrolytes

Question 1

What is the reference range for Ca?

Answer 1

8.6-10.2

Question 2

Why does corrected calcium need to be calculated?

Answer 2

mostly protein bound to albumin;
low albumin = falsely low Ca levels

Question 3

What is the ionized/ active reference range for Ca?

Answer 3

1.12-1.3

Question 4

What are s/s of severe hypocalcemia?

Answer 4

1. tetany
2. CV effects
3. CNS effects

Question 5

What IV form of Ca can only be given via the central line? Why?

Answer 5

CaCl2; vesicant

Question 6

What IV form of Ca needs to be metabolized to become active?

Answer 6

Ca gluconate

Question 7

What products cannot be given with Ca due to precipitation?

Answer 7

Phosphorus

Question 8

How is symptomatic hypocalcemia treated?

Answer 8

1. 1g CaCl IV followed by continuous infusion
2. 3g CaGLU IV followed by continuous infusion

Question 9

How is asymptomatic hypocalcemia treated?

Answer 9

1-2g CaGLU IV

Question 10

How is hypercalcemia treated in ICU?

Answer 10

1. IV fluids
2. IV diuretics

Question 11

What is the normal range of K?

Answer 11

3.5-5

Question 12

How is hypokalemia treated?

Answer 12

KCl 20-80 mEq PO/IV

Question 13

What agents temporarily treat hyperkalemia by driving K intracellularly?

Answer 13

1. albuterol nebulizer treatments
2. regular insulin 10U x 1 + IV dextrose 25g
3. Sodium bicarb 50 mEq IV x 1

Question 14

What agents permanently treat hyperkalemia by binding to K in the GI tract?

Answer 14

1. sodium polystyrene sulfonate (KAYEXALATE) 15-60g PO
2. Patiromer (VELTASSA) 8.4g PO QD
3. sodium zirconium cyclosilicate (LOKELMA) 10g PO TID

Question 15

What agents permanently treat hyperkalemia by renal excretion?

Answer 15

Furosemide 40mg IV x 1

Question 16

What directly removes K from the blood?

Answer 16

1. Hemodialysis
2. CRRT

Question 17

What agent is given for hyperkalemia to stabilize cardiac membrane and protect from arrhythmias?

Answer 17

Ca (Cl) 1g IV x 1

Question 18

What is the best way to treat hyperkalemia?

Answer 18

combination of agents that temporarily redistribute and agents that remove K +/- IV Ca

Question 19

What is the normal range for phosphorus?

Answer 19

2.7-4.5

Question 20

What is the treatment of mild/ asymptomatic hypophosphatemia?

Answer 20

PO KPhos or NaPhos

Question 21

What is the treatment of significant/ symptomatic hypophosphatemia?

Answer 21

1.5-2.7: 15 mmol IV
<1.5: 30 mmol IV

Question 22

How much K is in 15mmol KPhos?

Answer 22

22 mEq

Question 23

How much Na is in 15mmol NaPhos?

Answer 23

20mEq

Question 24

What is the risk of precipitation when calcium/phosphate product >55-60 mg/dL?

Answer 24

calciphylaxis

Question 25

What is the treatment of chronic hyperphosphatemia?

Answer 25

phosphate binders

Question 26

What is the treatment of acute hyperphosphatemia?

Answer 26

1. diuretics 2. dialysis 3. CRRT

Question 27

What is the normal range of Mg?

Answer 27

1.5-2.4

Question 28

Why is IV treatment preferred over PO for acute replacement of Mg?

Answer 28

oral replacement is slow, unreliable, and can further deplete Mg due to diarrhea

Question 29

How is mild-moderate hypomagnesemia treated?

Answer 29

Mg Sulfate 1-4g IV x 1 slowly

Question 30

How is severe (< 1) hypomagnesemia treated?

Answer 30

Mg sulfate 4-8g very slowly

Question 31

What is third spacing?

Answer 31

fluid shifts from intravascular plasma to interstitial (extravascular space)

Question 32

What is a normal serum osmolality?

Answer 32

275-300 mOsm/kg

Question 33

What is the range for isotonic solutions?

Answer 33

250-375 mOsm/L

Question 34

What type of fluid contributes most to third spacing?

Answer 34

hypotonic

Question 35

Which crystalloid solutions are purely isotonic?

Answer 35

1. 0.9% NS 2. Dextrose 5% in 0.9% NS 3. LR

Question 36

How many mEq are in 0.9% NS

Answer 36

154 mEq Na and 154 mEq Cl

Question 37

How many mOsm/L are in LR?

Answer 37

273 mOsm/L

Question 38

Which crystalloid solutions are hypotonic?

Answer 38

1. D5W 2. D5W in 0.45% NS

Question 39

How many mOsm/L are in D5W?

Answer 39

252 mOsm/L

Question 40

Which crystalloid solutions are hypertonic?

Answer 40

3% NaCl (NS)

Question 41

How many mOsm/L are in 3% NaCl?

Answer 41

1027 mOsm/L

Question 42

What is the highest mOsm/L that can be given via peripheral line?

Answer 42

900

Question 43

What are isotonic solutions used for?

Answer 43

1. fluid resuscitation 2. maintenance fluids

Question 44

What are hypotonic solutions used for?

Answer 44

1. correcting Na abnormalities 2. treating conditions with intracellular dehydration

Question 45

When should hypotonic solutions NOT be used?

Answer 45

head injury patients

Question 46

What are hypertonic solutions used for?

Answer 46

1. correcting Na abnormalities 2. decreasing cerebral edema

Question 47

Which balanced electrolyte solutions have lower incidence of kidney injury/ renal replacement therapy?

Answer 47

1. LR 2. Plasma -lyte

Question 48

Why do colloids have lower incidence of third spacing compared to crystalloid solutions?

Answer 48

large molecules increase oncotic pressure and don't redistribute as much

Question 49

What are the common colloid solutions?

Answer 49

1. Albumin 5% 2. Albumin 25% 3. synthetic starch colloids

Question 50

What SEs are more common in synthetic colloids?

Answer 50

1. bleeding 2. need for renal replacement 3. mortality

Question 51

What are signs of fluid depletion?

Answer 51

1. hypotension 2. tachycardia 3. decreased skin turgor 4. clammy extremities 5. altered mental status

Question 52

What is a normal sodium range?

Answer 52

135-145

Question 53

What is a normal Cl range?

Answer 53

97-107

Question 54

Why does hyponatremia cause neurologic effects?

Answer 54

fluid diffuses into brain cells and they swell causing cerebral edema

Question 55

What is associated with hyponatremia?

Answer 55

low serum osmolality

Question 56

How is hyponatremic hypervolemia treated?

Answer 56

1. fluid/water restriction 2. changing fluids

Question 57

How is hyponatremic hypervolemia caused?

Answer 57

1. cirrhosis 2. CHF 3. renal failure 4. fluid overload

Question 58

What is the common cause of hyponatremic euvolemia?

Answer 58

SIADH

Question 59

What is the range that plasma sodium can be increased when treating hyponatremia?

Answer 59

6-12 mEq/L/day

Question 60

What is the range that plasma sodium can be increased when treating acutely symptomatic hyponatremia?

Answer 60

1-2 mEq/L/h AND 6-12 mEq/L/day

Question 61

How is hypovolemic hypernatremia treated?

Answer 61

hypotonic/isotonic fluids

Question 62

How is euvolemic hypernatremia treated?

Answer 62

water replacement

Question 63

How does hyperglycemia cause pseudo hyponatremia?

Answer 63

glucose draws water from muscle cells into vascular space; more water in the vasculature decreases concentration of Na

Question 64

For each 100mg/dL of glucose above normal, how much is plasma sodium decreased?

Answer 64

-1.6 mmol/L

Question 65

What is SIADH?

Answer 65

secretion of inappropriate antidiuretic hormone

Question 66

What drugs can cause SIADH?

Answer 66

1. SSRIs 2. NSAIDs 3. opioids 4. antidepressants 5. antipsychotics

Question 67

What is diagnostic criteria for SIADH?

Answer 67

1. serum osmolality <285 2. serum Na <135 3. urine osmolality >200 4. euvolemic

Question 68

What is treatment of SIADH?

Answer 68

1. fluid restriction <1500 mL/day 2. low dose diuretucs 3. oral NaCl 4-16 g/day

Question 69

What is diabetes insipidus?

Answer 69

decreased secretion of antidiuretic hormone leading to decreased retention of water

Question 70

How does diabetes insipidus present?

Answer 70

dilute urine output >250 mL/h

Question 71

How is diabetes insipidus treated?

Answer 71

1. hypotonic solutions to replace free water 2. Desmopressin 1-2 mg IV/SQ BID 3. Vasopressin 1-15 U/h (not preferred)

Question 72

How much do we want sodium to decrease per hour when treating diabetes insipidus?

Answer 72

0.5 mEq/L/h