IVF and Diuretics

Question 1

How much sodium is in one level teaspoon?

Answer 1

5 mg of salt (NaCl)

~2 grams of sodium

Question 2

What is a normal plasma BUN?

Answer 2

10-20

Question 3

What is a normal blood creatinine?

Answer 3

around 1.0

Question 4

What is a normal blood glucose?

Answer 4

60-100

Question 5

What are the types of IVF?

Answer 5

D5 water

Normal Saline (0.9%)

half normal saline

lactated ringers

Question 6

Why can’t IVF just be water?

Answer 6

the infusion of such a hypotonic solution could cause cell lysis

Question 7

What is the equation for serum osmolality? What is the normal range?

Answer 7

2*Na + BUN/2.8 + Glucose/18

normal range is 285-295

Question 8

What are the components of D5W? How is this distributed in the body?

Answer 8

50 gm of dextrose in 1 liter of water = 50 gm/L (5% dextroes)

osmolarity of 278

sugar is metabolized, leaving only the water, which is distributed according to body water (333 ML in ECF and 667 mL in ICF)

ultimately <100 mL is left in the plasma (3/4 extravascular)

Question 9

What are the components of normal saline? How is this distributed in the body?

Answer 9

close to isotonic with serum

contains 9 gm of sodium chloride in 1 L (0.9%)

has osm of 308 (154 mEq of Na and 154 mEq of Cl)

1000 mL in the ECF and 0 mL in the ICF

ultimately 250 mL in the plasma

Question 10

What are the components of half-normal saline? How is this distributed in the body?

Answer 10

1/2 of normal saline, 4.5 g/L (0.45%)

667 mL in ECF and 333 mL in ICF

ultimately 167 mL remains in the plasma

Question 11

What are the components of lactated ringers? How is this distributed in the body?

Answer 11

contains 130 g/L of sodium and 109 g/L chloride

also contains 4 mmol/L potassium, 3mmol/L calcium, and 28 mmol/L lactate

900 mL ends up in the ECF and 100 mL in the ICF

ultimately ~225 mL in the plasma

Question 12

What are the daily water maintenance requirements for a patient who is NPO?

Answer 12

100 cc/kg for the first 10 kg

50 cc/kg for the next 10 kg

20 cc/kg for every kg over 20

therefore, a 70 kg person would need 1000 + 500 + 1000 = 2500 mL/day

Question 13

When is normal saline a good choice?

Answer 13

in patients who are volume deplete - provides sodium and chloride the kidney needs to maintain volume

Question 14

diuresis vs. natriuresis

Answer 14

diuresis produces more urine

natriuresis promotes salt excretion

Question 15

What are the classes of diuretics?

Answer 15

proximal tubule

distal convoluted tubule

loop diuretics

K+ sparing diuretics

Question 16

proximal tubule diuretics

Answer 16

acetazolamide is the main diuretic here

inhibits the activity of carbonic anhydrase, promoting the absorption of HCO3-

interferes with sodium absorption by inhibiting the HCO3-/Na+ pump

leads to loss of both sodium and bicarbonate - used for diuresis in the setting of metabolic alkalosis

weak diruetic because the rest of the kidney can compensate

causes a non-gap acidosis

Question 17

loop diuretics mechanism and uses

Answer 17

furosemide (Lasix), torsemide (Demadex), bumetanide (Bumex)

inhibits the Na+-K+-2Cl- symporter in the thick ascending limb of the loop of Henle

used for volume overload (rapid diuresis)

used for HTN particularly in chronic kidney disease

can also be used with normal saline to treat hypercalcemia

Question 18

side effects of loop diuretics

Answer 18

fluid and electrolyte imbalances - hypokalemia, hypocalcemia, and hypomagnesemia

volume depletion

ototoxicity

hyperuricemia

hyperglycemia

increased LDL and triglycerides

Question 19

thiazide diuretics mechanism and uses

Answer 19

hydrochlorothiazide (HCTZ), chlorthalidone, metolazone

inhibits the Na-Cl symporter in the distal convoluted tubule

show to decrease cardiovascular morbidity and mortality in HTN (low doses that do not cause hypokalemia)

a first line treatment option for hypertension

can also be ued to treat/prevent kidney stones

Question 20

side effects of thiazide diuretics

Answer 20

impotence

fluid and electrolyte imbalances - hypokalemia, hyponatremia, hypercalcemia

impaired glucose tolerance

increased cholesterol

Question 21

K+ sparing diuretics mechanism and uses

Answer 21

triamterene, amiloride, spironolactone, eplerenone

triamterene and amiloride inhibit the renal epithelial Na+ channels in the late distal tubule and collecting duct

spironolactone and eplerenone antagonize the mineralocorticoid receptor on epithelial cells in the late distal tubule and cortical collecting duct

used to avoid hypokalemia, use caution if at risk for hyperkalemia, good for hypertension