Test 1 Fluid and Electrolyte Disorders

Question 1

Formula for plasma osmolality

Answer 1

[2 x Na+] + [glucose/18] + [BUN/2.8]

Question 2

sodium content and solution type of 0.9% NaCl

Answer 2

• 154 mEq/L

- isotonic

Question 3

sodium content and solution type of Lactacted Ringers

Answer 3

• 130 mEq/L

- isotonic

Question 4

sodium content and solution type of Plasmalyte A

Answer 4

• 140 mEq/L

- isotonic

Question 5

types of sensible fluid loses

Answer 5

• gastrointestinal
• urine
• skin: sweating

Question 6

types of insensible fluid loses

Answer 6

• increased respiratory rate
• thermal / chemical burns
• misc: phototherapy, fever

Question 7

medications that causes SIADH

Answer 7

• amitriptyline
• nortriptyline
• haloperidol
• desmopressin
• carbamazepine
• oxcarbazepine
• cyclophosphamide
• citalopram
• sertraline

Question 8

medications that causes DI

Answer 8

• Cidofovir
• Lithium
• Amphotericin B
• Demeclocycline
• Foscarnet
• Vasopressin V2-receptor antagonists (conivaptan, tolvaptan)

Question 9

treatment options for SIADH

Answer 9

• fluid restriction
• correct underlying cause
• 3% NaCl for pts fluid restricted or symptomatic (acute 1st line)
• 0.9% NaCl for pts not fluid restricted or asymptomatic (acute 1st line)
• vasopressin receptor antagonist: conivaptan (acute 2nd line) | tolvaptan (chronic)
• Demeclocycline (chronic only)

Question 10

treatment options for DI

Answer 10

+ correct free water deficit for pts with severe symptoms (1st line)
+ maintenance medications (2nd line)
- central order of therapy: desmopressin, carbamazepine, indomethacin
- nephrogenic order of therapy: HCTZ, desmopressin, indomethacin or amiloride for lithium-related nephrogenic

Question 11

other name for SIADH

Answer 11

euvolemic hypotonic hyponatremia

Question 12

other name for DI

Answer 12

euvolemic hypernatremia

Question 13

correction formula for Na+

Answer 13

(0.6) (wt in kg) [Target Na+ (120 mEq) - measured Na+] = Total mEq of Na+ to raise sodium concentration to target

Question 14

What happens with rapid correction of hyponatremia?

Answer 14

Rapid correction of hyponatremia (> 12 mEq/L per day) is associated with the development of osmotic demyelination syndrome from demyelination lesions in the pons

Question 15

etiologies of hypokalemia

Answer 15

• β2-Receptor Agonists: albuterol, terbutaline
• Diuretics: furosemide, bumetanide, torsemide, HCTZ, chlorothiazide
• Amphotericin B
• Hypomagnesemia

Question 16

etiologies of hypomagnesemia

Answer 16

• magenesium citrate (increase GI loss)
• diuretics
• amphotericin B
• tacrolimus
• cyclosporine

Question 17

etiologies of hypocalcemia

Answer 17

• Hypomagnesemia
• loop diuretics
• calcitionin

Question 18

etiologies of hypophosphatemia

Answer 18

• sucralfate
• Ca2+ carbonate
• sevelamer
• acetazolamide
• insulin
• diabetic ketoacidosis
• alcoholism

Question 19

etiologies of hyperphosphatemia

Answer 19

• sodium phosphate enemas
• bisphosphonates (i.e., etidronate, pamidronate, zolendronate)
• rhabdomyolysis

Question 20

treatment options for hyperkalemia

Answer 20

• abnormal EKG -> administer Ca gluconate (peripheral) or CaCl (central)
• give insulin with or without dextrose depending on blood sugar
• consider albuterol
• consider NaCO3
• consider dialysis or exchange resin
• decrease total K stores: kayexalate (chronic)
• non-pharm. pts w/ reanl failure: hemodialysis
• non-pharm. pts w/ normal renal function: loop diuretics

Question 21

treatment options for hypercalcemia

Answer 21

+ symptomatic:
- kidney failure -> hemodialysis
- normal - moderate kidney function -> 1. NS, 2. loop diuretics, 3. IV calcitonin, 4. IV glucocorticoids
+ asymptomatic:
- Ca2+ < 12 mg/dL: monitor and eliminate underlying cause
- Ca2+ > 12 mg/dL: 1. NS, 2. loop diuretics, 3. IV calcitonin, 4. IV glucocorticoids, 5. biphosphonate

Question 22

bisphosphonates

Answer 22

block bone resorption; don’t work quickly; reserved for patients with chronic problems

Question 23

treatment options for hypermagnesemia

Answer 23

• 1st line: antagonize cardiovascular toxicity: calcium gluconate or CaCl
• 2nd line: enhance elimination; normal kidney -> NS bolus and IV loop diuretics; kidney failure -> consider hemodialysis
• eliminate / reduce Mg intake